NBSIR 76-1169

Rationale and Recommendations

For changes and Revisions to

the HUD Noise Measurement

Systems Specifications

Donald S. Blomquist, Marilyn A. Cadoff

Applied Acoustics Section

Institute for Basic Standards

National Bureau of Standards

Washington, D.C. 20234

October 1977

Final Report

Prepared for U.S. Department of Housing and Urban Development

Washington, D.C. 20410

NBSIR 76-1169

RATIONALE AND RECOMMENDATIONS

FOR CHANGES AND REVISIONS TO

THE HUD NOISE MEASUREMENT

SYSTEM SPECIFICATIONS

Donald S. Blomquist, Marilyn A. Cadoff

Applied Acoustics Section

Institute for Basic Standards

National Bureau of Standards

Washington, D.C. 20234

October 1977

Final Report

Prepared for U.S. Department of Housing and Urban Development

Washington, D.C. 20410

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director
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Table of Contents

Page

1. Introduction 1

2. Acceptance Tests of the HUD Noise Measurement System 2

2.1. Incoming Acceptance Test 2 2.2. Dummy Model Test 3 2.3. Preliminary Field Tests 3

2.4. Field Testing of the HUD Noise Measurement System .... 5

2.4.1. Rationale for Field Testing Phase 5 2.4.2. Field Testing Program 8

2.4.3. Results of the Field Testing 9

3. Recommendations for Changes and Revisions to the HUD Noise

Measurement System Specifications 14

4. References 16

5. Appendix A: Performance Specification for an Urban Noise

Exposure Measurement System 17

6. Appendix B: HUD's Noise Measurement System 30

7. Appendix C: Field Use Instructions 39

8. Appendix D: HUD Noise Measurement System Use Log 51

Acknowledgements 54

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Rationale and Recommendations for Changes and Revisions to

the HUD Noise Measurement System Specifications

Donald S. Blomquist

Marilyn A. Cadoff

ABSTRACT

In 1973, the Office of Noise Abatement Research, Department of Housing

and Urban Development, contracted with the Applied Acoustics Section of the

National Bureau of Standards to develop a noise exposure measurement

system. This system was subsequently developed, seventeen prototype units

were procured, and a full-scale laboratory and field evaluation of the

units were conducted. This report discusses the results of the evaluation,

as well as the rationale behind and recommendations for changes and

revisions to the HUD noise measurement system specifications.

Key Words: Acoustics; community noise; environmental impact; noise;

noise exposure measurement system; sound.

1 . INTRODUCTION

In 1973, the Office of Noise Abatement Research, Department of Housing

and Urban Development, contracted with the Applied Acoustics Section of the

National Bureau of Standards to develop a noise exposure measurement system

(NEMS). This system would provide an inexpensive, reliable means for

accurate, quantitative assessment of the noise environment at prospective

building sites or other areas of concern regarding noise. It would be

specifically tailored to measure conformance to the interim .external noise

exposure standards of HUD Departmental Circular 1390.2. [1]— Thus, NBS

designed a self-contained system which consisted of two main components.

There was a Monitor which collected the following data over a 24-hour

period

:

1 . The accumulated time that 80 dB(A) was exceeded

.

2. The accumulated time that 75 dB(A) was exceeded.

3. The accumulated time that 65 dB(A) was exceeded

.

4. The accumulated time that 45 dB (A) was exceeded.

5. The number of times 80 dB(A) was exceeded.

6. The accumulated time the iwind1 was greater than 20

1 / The numbers in brackets indicate the literature references at the end

of this report.
The other component of the system was a Reader, which read out the above

data, as well as the Monitor identification number, to the field investigator when the test was completed. Once the design was completed,

NBS built two prototype systems and field tested them to ensure that they

operated properly. When it was assured that the NBS-built systems were

operating as desired, a set of system specifications were drawn, and a bidding procedure commenced to award a contract to a commercial firm to

build seventeen NEM systems to be used for field testing by HUD personnel.

The contract was subsequently awarded and the systems built, and a full

field test and evaluation of each system was conducted.

The tests of each commercially-built NEMS were carried out in four

steps: (1) an incoming acceptance test; (2) a dummy model test; (3)

validation of the system; and (4) field testing of the system by HUD

personnel. This report will discuss each of these tests as well as present the results of the tests which led to the changes and revisions to

the HUD noise measurement system specifications which are recommended at

the conclusion of this report. A copy of the revised performance

specification in which the changes recommended in this report are incorporated is given in Appendix A.

2. ACCEPTANCE TESTS OF THE HUD NOISE MEASUREMENT SYSTEM

2.1. Incoming Acceptance Test

Each of the seventeen measurement systems was tested by NBS upon

receipt from the contractor. The acceptance tests consisted of the

following: (1) the A-weighting was checked to determine frequency

response; (2) the detectors were tested to determine crest factor

capability; (3) the operation of the comparators were tested to determine

that the quantitazation levels were as specified in Circular 1390.2; (4)

the signal-to-noise ratio was determined: (5) the operation of the memory

registers was determined; and (6) the accuracy of the windspeed indicator

was determined. As a result of these tests, three units were rejected —

two because of memory and/or clock failure and one because the A-weighting

did not meet specifications.

The above tests were then performed in an environmental chamber in a temperature range of -20 to 80°C at 100% relative humidity, and it was

found that the system drifted more than the specifications allowed. This

was due to the fact that the piezoelectric microphone, which had been

utilized in the NBS design and incorporated into the contractor's system,

had a temperature coefficient that was much greater than specifications.

This was caused by a materials problem in the manufacture of the

microphone cartridges and was solved by changing to a conventional (air)

condenser microphone. However, in order to make the new microphone

compatible with the system, extensive redesign was necessitated. The

input amplifier had to be redesigned so that it could be interfaced with

the high impedance condenser microphone. Additionally, gains had to be

changed due to the characteristic differences between the piezoelectric

and condenser microphones. Finally, the input amplifier had to be further

redesigned because of instability caused by the microphone preamplifier.

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After the system was redesigned, the tests were then rerun in the

environmental chamber under the temperature and humidity conditions, and

the measurement system conformed to specifications.

2.2. Dummy Model Test

The main purpose of this test was to determine the susceptability of

the system to vandalism and theft. Four cases having the same size and

configuration as the actual noise measurement system were constructed of

wood. These cases were then placed in the same polyurethane covers as are used in the measurement system, and the same windscreens and goosenecks as are used in the system were attached to the covers. A wind sensor,

constructed of wood, but painted the same color as an actual one, was also

attached. Three of these dummy systems were mounted on utility standards

at different locations in Washington, D. C. for a period of one week. The

fourth dummy unit was mounted near Interstate 270 in Rockville, Maryland.

The mounting heights varied from 2 to 4 meters. In all cases, the dummy

systems were not vandalized.

2.3. Preliminary Field Tests

Although the measurement system was tested for environmental effects

during development and accuracy and drift were measured, it was considered

desirable to conduct parallel measurements with more conventional measurement techniques to demonstrate both the simplicity and versatility of the

system and also its accuracy and precision. Thus, the HUD measurement

system and two other systems, were used to measure noise in the following

environments: (1) a suburban area subject to light traffic and (2) near an Interstate highway subject to heavy traffic.

The first series of measurements were made at site 1, which was on the

NBS grounds along Quince Orchard Road. Data were collected using three

systems: (1) the HUD noise measurement system; (2) a level recorder and

statistical distribution analyzer; and (3) a computer with an analog-todigital converter and digital magnetic tape. The computer system included

an asynchronous external memory so that data were written on magnetic tape

without losing new input data and a time of day clock for synchronizing

data between the HUD system, the level recorder system, and^yhe computer.

The digital magnetic tapes were read on ^he NBS Univac 1108— computer and

the data were binned in 5 dB increments.— A complete list of equipment

for systems 2 and 3 is given in Tables 1 and 2.

2 / —Certain commercial equipment, instruments , and materials are identified

this report in order to adequately specify the experimental procedure,

no case does such identification imply recommendation or endorsement by

the National Bureau of Standards, nor does it imply that the material or equipment identified is necessarily the best available for the purpose.

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In

3 / A more complete discussion of the computer system is given in Ref. 2.

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Table 1. List of equipment used in level recorder system.

Manufacturer Instrument Model No.

B & K Instruments Outdoor Microphone 4921

B & K Instruments Amplifier 2606

B & K Instruments Graphic Level Recorder 2305

B & K Instruments Statistical Distribution Analyzer 4420

Jable 2. List of, equipment used in computer system.

Manufacturer Instrument Model No.

B & K Instruments Outdoor Microphone 4921

B & K Instruments RMS/Log Converter 215

National Bureau of

S tandards

Interface/ADC —

Raytheon Computer System 704

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For the level recorder and computer systems a B & K type 4921 outdoor

microphone system was used. This system has a 1 kHz electrostatic actuator

for calibration and was remotely calibrated under computer control every 52

minutes. This system has the advantage that it can be used under any

weather conditions. The first validation test was conducted on July 25,

1974 for a period of 24 hours, and the results are given in Table 3.

As can be seen from the table, there was reasonable agreement between

the results obtained using the HUD and computer systems. Both systems

could be in specification and still not be in exact agreement because of

allowances in A-weighting network and gate trip points. However, the

differences between these two systems and the level recorder system are much greater than would be expected. Possible reasons for these

differences are: (1) the level recorder has a servo system which has

equivalent meter ballistics which are not present in the HUD or computer

systems; (2) the writing speeds possible on the level recorder do not

correspond exactly to "fast" or "slow" as specified in American National

Standard SI. 4-1971 [3] and (3) the level recorder is really recording the

mean detected value as opposed to the root-mean-square value which the HUD

and computer systems record.

Data for site 2, which was approximately 30.5 meters from the center

of the near lane on Interstate 270, were taken for a 24-hour period

beginning August 10, 1974, using the HUD system and the computer system.

The results are given in Table 4. It should be noted that no level

recorder system data were obtained at this site. It was decided not to use

the level recorder system for this phase of the tests, as it did not

conform to American National Standard SI. 4 [3] as the other systems did.

The results of the test show that the HUD system agrees very well with the

computer system. The differences, which are the greatest in the 45 to 65

and 65 to 75 intervals, appear to be due either to differences in the gate

trip points or the tolerance in the A-weighting network of the two systems.

2.4. Field Testing of the HUD Noise Measurement System

2.4.1. Rationale for Field Testing Phase

The tests discussed in previous sections of this report showed that

the HUD noise measurement system would probably not be subject to vandalism

and that the data recorded by the system were accurate. The field phase of

the testing program was designed to provide information as to how well a person unskilled in acoustical measurements and instrumentation — the user — could carry out the instructions and operations necessary to utilize the

system. (The HUD Noise Measurement System Operation Instructions and the

Field Use Instructions for the HUD Noise Measurement System are given in

Appendices B and C, respectively.) Basically, when the measurement system

is used, the operator must perform seven major steps: (1) determine the

location where the greatest noise exposure most probably exists; (2)

calibrate the Monitor; (3) mount the Monitor at the location found in step

1 and activate it; (4) remove the Monitor from the mounting; (5)

recalibrate the Monitor and read the data; (6) interpret the results of the

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Table 3. Results of the validation test conducted on July 25-26,

1974, on NBS grounds along Quince Orchard Road (Site 1)

.

A-weighted Sound

Level Interval

(dB)

Time Interval (hr.)

HUD

System

Computer

System

Level Recorder

System

Less than 45 2.74 3.97 .106

45-65 18.66 17.65 22.74

65-75 2.48 2.05 1.23

75-80 .07 .053 .028

80-85 .00 .006 .002

Table 4. Results of the validation test conducted on August 10-11,

1974, approximately 30.5 meters from Interstate 270 (Site 2).

A-weighted

Sound

Level Interval

(dB)

Time Interval (hr. )

HUD System Number Computer

4087 4089 4090 System

Less than 45 .23 .65 .36 .00

45-65 19.94 21.02 20.67 21.46

65-75 3.61 2.02 2.79 2.42

75-80 .19 .65 .16 .09

Greater than 80 .00 .00 .02 .00

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measurements; and (7) decide whether' or not additional measurements are necessary from steps 1 and 4.

The first step in the deployment of the measurement system is to

determine the most appropriate location(s) for the Monitor. The NBS

instructions for locating the Monitor on a site utilize information, in

the form of written instructions, nomographs, and tables, given in the

present Noise Assessment Guidelines [4] . One of the purposes of the field

testing was to determine the suitability of the NBS instructions by

examination of (1) user acceptance, (2) ease of use, (3) expert judgment,

(4) the time required to use the instructions, and (5) consistency.

The next steps in the use of the system are calibration and

mounting. The fundamental problem in calibration is following

instructions, and the appropriateness of the instructions were judged by

the amount of time it took to complete the task and the number of errors which occurred in performing the task. Other items which were evaluated

were (1) the intensity and discriminability of the light-emitting-diode

(LED) indicators and (2) the ease with which the system gain could be

adjusted by the operator. Finally, any problems with the automatic

shut-off of the calibrator were determined; e.g., should the "on" time be

changed, and were the instructions for the battery check adequate.

After the system is calibrated, it must be mounted on the field

mounting pole or a utility standard. The testing program evaluated the

entire mounting procedure with particular attention to the problems of

mounting at a lower height than specified, dropping the system, and the

difficulty of using the Monitor strapping.

After the 24-hour measurement period, the operator must remove the

Monitor, perform the second calibration, and read out the data. Again,

the potential for dropping the system is present if the operator does not use the shock cord or if the strapping is difficult to cut. The operator

must again follow instructions for the second calibration as well as for

connecting the Monitor to the Reader. The appropriateness of the

instructions were determined by analysis of the number of errors made and

by the amount of time it took to perform the operations. In addition, the

effect of sunlight on the visibility of the LED readout in the Manual

Reader was determined. Finally, in using the measurement system during

this phase of the procedure, the most probable items to be damaged were

the wind sensor and microphone. Damage to the microphone was indicated by

the operator’s inability to calibrate the system. Damage to the wind

sensor was determined by a visual examination using a set of instructions.

The adequacy of the instructions was determined by the field testing.

Finally, after the measurements are made, the results must be

interpreted. Through examination of the results, the operator must decide

whether any further measurements need to be made, and if the results

obtained with the system seem to be reasonable. This can be assessed by

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comparing the measured results with those predicted from the NBS

instructions. The field testing was to establish the allowable difference

between the predicted and actual results.

2.4.2. Field Testing Program

A HUD noise^yeasurement system was delivered to each of the ten HUD

regional offices— during the months of May and June 1975. During July and

August 1975, one additional NEMS was delivered to the New York, Chicago,

and San Francisco offices. During the initial delivery of the NEMS, a representative from NBS trained HUD field personnel in the use of the

system. The usage was closely monitored by NBS personnel during the first

six months through written use logs (a three-page questionnaire which was

filled in by the user each time a site was measured) and telephone calls.

Much of the data ^ported in Section 2.4.3 of this report is taken directly

from the use logs— , and a copy of the use log is reproduced in Appendix D.

In regard to finding a location on which to mount the Monitor,

instructions were given to several of the HUD regional office personnel at

the time of initial delivery of the system. They were to use these

instructions to determine the appropriate location(s) of the Monitor at a typical site. In parallel with the HUD representative, a person from NBS

also independently determined the the appropriate location. Ideally, of

course, both would derive the same location. The appropriateness of the

location was then judged by the NBS project leader. In addition, HUD

personnel using the instructions were interviewed regarding difficulties

encountered while interpreting the instructions, and were asked to suggest

improvements in wording, format, organization, etc.

Following the initial deliveries of the HUD system to the regional

offices, the HUD personnel were left on their own to conduct the field

testing and return the use logs to NBS. The results of this field testing

and the NBS recommendations for changes to the HUD system which resulted

from the field testing are given in subsequent sections of this report.

The HUD regional offices are located in the following cities: Boston,

Massachusetts; New York, New York; Philadelphia, Pennsylvania; Atlanta,

Georgia, Chicago, Illinois; Dallas, Texas; Kansas City, Kansas; Denver,

Colorado; San Francisco, California; and Seattle, Washington.

5V

In all, 106 Use Logs were returned from the Regional Offices. However,

for a number of reasons (which will be discussed in the course of the

report), 20 of the logs reported no data from the Monitor.

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2.4.3. Results of the Field Testing

Determination of the location where the greatest noise exposure exists : From the information given in the Use Logs, virtually no difficulty was encountered in finding a location for the Monitor. Only four Use Logs

reported having had difficulty, and the problem seemed to be caused not by

being able to determine the location, but by being unable to find a tree,

utility standard, or post on which to mount the Monitor. The time taken to

find the location ranged from one minute to one hour, with about half the users reporting it took five to ten minutes. Eighty- three percent of the users determined the location in ten minutes or less, and 99 percent in 30

minutes or less. In tests where NBS personnel determined the Monitor

location simultaneously with HUD personnel, the locations chosen were very

similar. This verified that the instructions for this phase of the test

were sufficiently clear and detailed.

Calibration of the System ; The initial calibration of the HUD measurement

system appeared to cause the user little problem. Only four of the Use

Logs specifically reported problems calibrating the system. From these

four, the following problems were cited: the calibration enable light went

back and forth between red and green; the calibrator "on" time would not

hold for the full 45 seconds,; the battery check light did not come on; the

battery check light flashed; the Monitor would not calibrate in hot

temperatures; the Monitor would not calibrate with the wind sensor on; the

operation is too difficult to be done in the field; and the calibrator

itself was malfunctioning. In addition, two of these Use Logs reported the

time it took to perform the calibration — one reported a time of 30

minutes. During this phase of the program, no one reported having

difficulty in adjusting the system gain.

Finally, there was a question in the Use Log designed to indicate the

intensity and discriminability of the LED indicators. Forty-eight of the users indicated that they had no trouble reading the indicators.

Twenty-nine said that they could read them, but with difficulty, and six of

the users said that they were very difficult to read in bright sunlight.

As this question was only asked of persons who performed the calibration at

the measurement site, the above responses do not sum to 105 because seven

users did not answer the question and the rest calibrated the system in

their office or car.

Mounting the Monitor : The mounting of the Monitor appears to be the first

phase of the testing which caused any substantial problem. Seventy-two

users reported that they experienced no difficulty, twenty-eight indicated

that they did have difficulty, and five users provided no information. Of

those who experienced difficulty, the main complaints seemed to be that the

shock cord was too short and that the banding of the system was difficult

to accomplish. Each of these complaints was reported eleven times. Other

problems that occurred in mounting the system were that the shock cord

fasteners could not be secured well, the wind sensor was difficult to

mount, bending the buckle ears was difficult, the cutting tool was

difficult to use, and lack of experience. The time taken to mount the

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Monitor ranged from one minute to 60 minutes, with 50 percent of the users reporting that it took 10-15 minutes. Seventy-eight percent mounted the

Monitor in 15 minutes or less, and 94 percent in 30 minutes or less.

The mounting height had to be sufficiently high enough to discourage

and/or prevent vandalism and theft. A minimum height range of eight to

twelve feet was recommended. From the Use Logs, it was determined that 63%

of the users mounted the Monitor within this range, and an additional 25%

mounted the system at heights ranging from 13 feet to 65 feet. Fifteen

users, or fourteen percent, mounted the system lower than the recommended

height

.

Dismounting the Monitor and performing the second calibration : Removing

the Monitor from its mounted position caused virtually no problems serious

enough to be noted in the Use Logs. Only one user noted having a problem,

and this was caused by being unable to get the cutters underneath the strap

to free the Monitor from the mounting pole. The user solved his own problem in subsequent tests by inserting a block of wood between the strap

and the pole, thereby leaving a space large enough to insert the cutters.

The second calibration of the HUD system caused substantially more

problems than the first. Seventeen Use Logs reported failing to perform

the second calibration. Four Use Logs did not specify whether they were successful or not, three did not complete the test runs due to excessive

wind, and 82 successfully performed the second calibration. Of the 17

unsuccessful attempts, only four noted in the logs what they believed the

problem to be. One user thought that the calibrator was at fault and three

noted that they were unable to perform the calibration with the wind sensor

attached to the system.

Readout of the data : As noted earlier, 20 (19%) of the Use Logs returned

to NBS (out of 106 total) reported no data. Of these, six Logs gave no reason as to why no data were collected. From the other logs, a variety of

reasons were given. One person voided his data because they exceeded 24.05

hrs . In another case, the system was vandalized. Two Use Logs noted that

the wind speed exceeded the capacity of the system. This latter instance

happened to the same user two times in a row, and in order to ascertain

whether the system was malfunctioning, he ran a test in his office. The

system was functioning properly but no data were reported for this run. In

two cases, the tape on the automatic reader jammed, and the data were

printed out superimposed and thus illegible. In seven cases, data were not

obtained because the user was unable to calibrate the system. In one case,

the user could not calibrate and did not attempt to read the data. In the

other instances, the users, after trying and failing to calibrate,

attempted to read the data, but all that was printed out by the Reader was

"UC".

Interpreting the data : The data from these tests are to be interpreted as specified in HUD Departmental Policy Circular 1390. 2 [ 1 ] . As the data were

interpreted by HUD personnel, two of the sites tested were judged to be

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unacceptable, thirteen were judged to be discretionary-normally

unacceptable, sixty-five were judged to be discretionary-normally

acceptable, and two were judged to be acceptable. With only 18.5% of the

sites falling into the unacceptable categories, one might question the

necessity of using such a system to characterize the sites. However, when

the data were returned to NBS, they were re-evaluated to see how many sites

might be marginal in terms of their category of acceptability. In other

words, for a site to be considered discretionary-normally acceptable, its

noise climate must not exceed 65 dB(A) more than 8 hours/ 24 hours. How

many sites were there in which 65 dB(A) was exceeded for 6-8 hours/24

hours, and thus almost placing them in the discretionary-normally

unacceptable category (exceeds 65 dB(A) 8 hrs./24 hrs)? In addition, how

many sites were judged discretionary-normally unacceptable (does not exceed

75 dB(A) more than 8 hrs/ 24 hrs.) but where 75 dB(A) was exceeded 6-8

hrs/24 hrs., thus almost qualifying it for the unacceptable category? When

the data were examined in this manner, almost a third of the sites would be

in these marginal categories: 75 dB(A) was exceeded 6-8 hrs/24 hrs. at one site and 65 dB(A) was exceeded 6-8 hrs/24 hrs. at 26 sites. These 27 cases plus the fifteen which were clearly classified in unacceptable categories

comprise almost 51% of the sites for which data are reported. This clearly

indicates a need for a device which will provide an inexpensive, accurate

assessment of the noise to which potential HUD construction sites are subjected.

Other problems encountered by HUD field test personnel :

a) System failures: A log was kept by NBS of failures to the HUD

Noise Measurement System. As of February 5, 1976, thirteen failures had been reported by the HUD regional field offices. The reasons for these failures are given in Table 5.

b) Wind sensor: Three problems arose with the use of the wind

sensor. Two of the Use Logs noted that it was difficult to

connect the wind sensor to the Monitor. Although this does not

appear to be significant, there were many verbal complaints by

HUD personnel to NBS about this problem. Three of the Logs

mentioned that it was impossible to mount the Monitor with the

wind sensor attached. In all three cases, the user operated the

system without attaching the wind sensor. Finally, although it

does not appear in any of the Logs, it was reported verbally to

NBS that there were several instances where the wind sensor shorted out due to moisture getting into it, thereby causing the

data which had been collected to be voided.

c) Automatic Reader: The Use Logs mentioned two problems that

occurred with the Automatic Reader. In three instances, it was reported that the printout on the paper tape was faulty. The

numbers were printed by an arrangement of dots and in all of

these cases some of the dots were not being printed. For . example, a zero was normally printed in the following way

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Table 5. Reasons and number of occurrences for failures

of the HUD Noise Measurement System.

Reason No. of Occurrences

Preamplifier damaged by moisture 2

Microphone damaged by removing

calibrator too rapidly 4

Bad batteries in Reader 1

Bad calibrator 1

Windsensor damaged in transit 1

Windsensor damaged by mishandling 2

Automatic Reader damaged in transit 2

TOTAL 1

3

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# #

w During the malfunction, zero appeared as ,•* , which bears more

resemblance to a nine than a zero. Obviously, this caused

confusion in reading the data, and in one case, necessitated a duplicate run to verify the results.

The other problem, which was reported twice in the Use Logs and a number of times by telephone, was that the paper tape jammed in

the Automatic Reader, thereby causing all the characters to be

printed at one position and making the data unreadable. From

discussions with users, it appeared that this was caused by

failure to secure the connector used for interconnecting the

Reader and the Monitor in its holder iif the Reader lid. When the

connector was not held in place, it knocked the tape cover of the

paper holder loose, causing the paper to become unthreaded. If

the paper was not rethreaded correctly, it would bind, causing

the characters to be printed superimposed.

In spite of the aforementioned problems, many users verbally

expressed a strong preference for the Automatic Reader as opposed

to the Manual Reader.

d) Carrying case for the HUD System: One Use Log made the comment

that the latch on the HUD System carrying case had broken. In

fact, three original carrying cases (which were ordinary suitcases) used for the system were ruined because they were not

sturdy enough to withstand the rigors of field testing. Two

aluminum cases were purchased to try out as a possible replacement for the original cases. They were taken into the field in

the New York and San Francisco HUD regional offices, and they

have remained in excellent condition throughout the testing

program.

e) Moisture problems: It was reported several times by telephone

and once in the Use Logs that condensation and/or water was getting inside the Monitor case. Since this had the potential of

shorting out the Monitor, it was decided to pack a dessicator in

the lid of the Monitors. Although one user has subsequently

complained that the dessicator made the case door difficult to

shut, there have been no moisture problems reported since the

dessicator was placed in the case.

f) Several persons reported that they lost their data because they

inadvertently turned off the main power switch of the Monitor

while they were dismounting it.

g) There were a number of complaints, both verbal and written, about

the difficulty of connecting the windsensor to the Monitor. It was not possible for the user to see the connection point while

performing the operation, and he had to depend on a sense of

feel. Also, the manner in which the connection had to be made

was causing the connection point to wear out rapidly.

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3.

RECOMMENDATIONS FOR CHANGES AND REVISIONS TO THE

HUD NOISE MEASUREMENT SYSTEM SPECIFICATIONS

As a result of the field testing, thirteen changes to the HUD System

specifications are recommended. Each change will be discussed briefly

below.

1. Carrying Case : As was discussed earlier, the original carrying

cases did not successfully withstand use in the field. Two

aluminum cases which were purchased as experimental replacements

have performed with no failures. Therefore, it is recommended

that the carrying case used for the HUD System be of the aluminum

type or a type which will perform equally as well as the aluminum

case

.

2. Clip to hold paper in place in Automatic Reader : To prevent the

paper tape from becoming unthreaded in the Automatic Reader, it

is recommended that a clip be added to hold the paper in place.

This eliminates the possibility that the paper will become

unthreaded, be rethreaded improperly, subsequently bind, and

print out the characters superimposed.

3. Automatic Reader : It is recommended that the Manual Reader be

dispensed with, and that only the Automatic Reader be used with

the HUD System.

4. Print head : Based on cost considerations, a new print head for

the Automatic Reader will be utilized. Use of this new print

head will reduce the cost of this particular item in the system

by a factor of four.

5. Microphone : It is recommended that the one-half-inch condenser

microphone currently specified be replaced with an air condenser

or electret microphone which is less expensive and more rugged.

It was found that the one-half-inch microphone Is too fragile for use in field testing by acoustically inexperienced personnel.

6. Dessicator for Monitor lid : To eliminate moisture problems which

occurred in the field, it is recommended that a dessicator be

packed into the lid of the Monitor.

7. Separate container for banding material : The banding material

for the HUD System is made of stainless steel and is quite bulky

and heavy. Many users complained that it made the carrying case quite heavy to carry, and, in addition, they were afraid it would

damage the more sensitive acoustical equipment. Thus, it is

recommended that a separate case be used to carry the banding

material

.

14
9.

10 .

11 .

12 .

Rainshroud for wind sensor : The wind sensor had originally been

designed as follows:

Rain was entering the sensor at points a and b. This shorted out

the sensor, causing it to indicate that the performance of the

sensor had been exceeded for the whole period the Monitor was in

operation. Thus, the data had to he voided and the test

repeated. To prevent water from getting into the sensor, it is

recommended that a rainshroud be added to the wind sensor, as in

Shock cord : Due to the problems . encountered by the persons who

conducted the field testing, it is recommended that the 18-inch

shock cord be replaced with a longer cord which would be

sufficient to encircle utility standards and trees of average

circumference with no difficulty.

Batteries : The battery pack which is used in the Monitor is

extremely difficult to construct — it takes almost two man days

for NBS personnel to construct one pack. Therefore, in order to save time, it is recommended that a battery system which can more easily be replaced be substituted for the one currently being

Switch guard : It is recommended that the Monitor switch be

covered with a guard, so that if it is inadvertently hit, the

Monitor will not be turned off prematurely.

Events > 80 dB : As the Monitor is now designed, it registers any

noise events greater than 80 dB which have a duration of one second or more. It is believed that many spurious events thus

tended to be registered as part of the data. To prevent this

occurrence, it is recommended that for events greater than 80 dB,

the effective duration be increased from one second to ten

seconds

.

Windsensor connector : It is recommended that the windsensor

connection be redesigned both to facilitate ease of operation and

to reduce the wear and tear to this point of the system.

the following diagram.

15
4. REFERENCES

[1] "Noise Abatement and Control: Departmental Policy, Implementation

Responsibilities, and Standards", Departmental Circular 1390.2, U. S.

Department of Housing and Urban Development, Washington, D. C., August

4, 1971. Change No. 1, September 1, 1971.

[2] Fisher, R. L. , Blomquist, D. S . , Forrer, J. S., and Corley, D. M. , A

minicomputer-based system for the measurement and analysis of

community noise, NBSIR 75-692 (National Bureau of Standards,

Washington, D. C., May 1975).

[3] American National Standard Specification for Sound Level Meters,

Si. 4-1971 (American National Standards Institute, New York, New York,

April 27, 1971).

[4] Schultz, T. J. , and McMahon, N. M. , Noise Assessment Guidelines (U. S.

Department of Housing and Urban Development, Washington, D. C., August

1971).

16
5. APPENDIX A

Performance Specification

for an Urban Noise Exposure Measurement System

1 . BACKGROUND

These performance specifications are for a complete portable urban

noise exposure measurement system for use in enforcing the U. S. Department

of Housing and Urban Development Circular 1390.2, Noise Abatement and

Control: Departmental Policy, Implementation Responsibilities, and

Standards. This policy statement establishes specific requirements for

noise abatement and control which govern approval of projects under all

Departmental programs. In this policy statement, the following interim

standards are established:

External Noise Exposures : Sites for New Residential Construction

(single or multifamily)

General External Exposures

Unacceptable

Exceeds 80 dB(A) 60 minutes per 24 hours

Exceeds 75 dB(A) 8 hours per 24 hours

Discretionary -- Normally Unacceptable

Exceeds 65 dB(A) 8 hours per 24 hours

Loud repetitive sounds on site

Discretionary — Normally Acceptable

Does not exceed 65 dB(A) more than 8 hours per 24 hours

Acceptable

Does not exceed 45 dB(A) more than 30 minutes per 24 hours

Interior Noise Exposures : For New and Rehabilitated Residential

Construction.

Sleeping Quarters

Acceptable

Does not exceed 55 dB(A) 60 minutes per 24 hours

Does not exceed 45 dB(A) 30 minutes between 11 p.m. to 7 a.m.

Does not exceed 45 dB(A) 8 hours per 24 hours.

17
Note: All A-weighted sound levels referred to in Policy Circular 1390.2

and in this performance specification are relative to a reference sound

pressure of 20 micropascals.

The Department of Housing and Urban Development has published noise

assessment guidelines that are used as site screening tools. These guidelines

provide the means for separating sites that are clearly acceptable from those

clearly unacceptable. Resolution of appellate applications, or of cases where

the site classification is indeterminate, requires a means for instrumental

measurement of physical data. These performance specifications are for a measurement system to classify a building site relative to the interim

standards cited above.

The National Bureau of Standards has developed and field tested prototype

instrumentation to implement measurements against Interim Standards; while all

details of this system will be made available to the contractor, it is the

contractor’s responsibility to determine that these performance specifications

are met.

2. INSTRUMENTATION SPECIFICATIONS

The instrumentation system shall consist of a "Monitor", which is to be

left at the desired location for at least 24 hours and a "Reader", which

interrogates the Monitor. The basic Monitor (see Sec. 2.1) shall be designed

specifically to collect the data required for characterizing the noise

exposure in terms of the above-cited external noise exposure standards. An

attachment ("Time-of-Day Clock" — see Sec. 2.3) to the Monitor shall enable

its use for collection of the data required for characterizing the noise

exposure in terms of the above-cited interior noise exposure standards. The

Reader is a unit capable of interrogating the Monitor. The Reader provides

printed output of the data (see Sec. 2.2).

2.1 Monitor Specifications

The Monitor shall be a self-contained, battery-operated unit, consisting

of a mounting assembly, and electronic package, a microphone and a weather

screen, capable of registering, on internal memory, the data specified in Sec.

2.1.8. There shall be no way to read the memory directly; this shall be

possible only through use of the Reader.

The Monitor shall consist of six major modules: (1) amplifier and

A-weighting network, (2) detector and quantization, (3) digital clock, (4)

digital scaling, (5) memory, and (6) calibration. The Monitor also includes

an acoustic calibrator and a microphone with windscreen.

2.1.1 Frequency Response

The System response to sound of random incidence, with the microphone

mounted in its normal configuration relative to the Monitor, and with the wind

and weather shield in place, shall be as shown in Table A-l (relative to a

18
Table A-l. HUD Noise Measurement System response to

random incidence sound.

Frequency*

Hz

A-Weighting

Relative Response

dB

Tolerance

dB

10 -70.4 +4, -oo v 12.5 -63.4 +3.5, -oo 16 -56.7 +3 , -oo 20 -50 .

5

+2.5

25 -44.7 +2

31.5 -39.4 +1.5

40 -34.6 +1.5

50 -30.2 +1

63 -26.2 +1

80 -22.5 +1

» 100 -19.1 +1

125 -16.1 +1

160 -13.4 +1

200 -10.9 +1

250 - 8.6 +1

315 - 6.8 +1

400 - 4.8 +1

500 - 3.2 +1

630 - 1.9 +1

800 - 0.8 +1

1000 0 +1

1250 + 0.6 +1

1600 + 1.0 +1

2000 + 1.2 +1

2500 + 1.3 +1

3150 + 1.2 +1

4000 + 1.0 +1

5000 + 0.5 +1.5, -2

6300 - 0.1 +1.5, -2

8000 - 1.1 +1.5, -3

10000 - 2.5 +2, -4

12500 - 4.3 +3 , -6

16000 - 6.6 +3, -oo 20000 - 9.3 +3, -oo

The maximum deviation of the free-field relative

response level as a function of angle of incidence

with respect to the random incidence response level

shall not exceed the values given in Tables A-2 and A-3.

*Nominal frequencies. Exact frequencies, to be

used for desim^gnd test, are generated using

f = 1000 x 10 where m is a positive or negative integer.

19
Table A2

Maximum allowable deviation of free-field relative response level with

respect to random-incidence relative response level when the angle of

incidence is varied from 45° to 90° from the axis about which the

response is most nearly cylindrically symmetrical.

These allowances are added arithmetically to the respective tolerance

limits in Table 1.

Frequency

Hz

Allowance

dB

31.5 to 2000 +1, "I

2000 to 4000 +1.5, -1

4000 to 5000 +2, -1.5

5000 to 6 300 +2.5, -2

6300 to 8000 +3, -2.5

8000 to 10000 +3.5, -3.5

10000 to 12500 +4, -6.5

Table A3

Maximum allowable deviation of free-field relative response level for sounds

arriving at any angle of incidence with respect to random-incidence relative

response level for any angle of incidence

These allowances are added arithmetically to the respective tolerance limits

in Table 1.

Frequency

Hz

Allowance

dB

31.5 to 2000 +1.5, -1

2000 to 4000 +2.5, -2

4000 to 5000 +3.5, -3

5000 to 6300 +4, -4

6 300 to 8000 +5.5, -5.5

8000 to 10000 +6.5, -8

10000 to 12500 +7.5, -11

20
frequency of 1000 Hz), within the tolerances indicated.

\ At frequencies below 10 Hz, the omnidirectional response of the system

shall decrease with decreasing frequency at a rate equal to or greater than 12

dB per octave. At a frequency of 32 kHz, the omnidirectional response of the

system shall be less than that at 1 kHz by an amount equal to or greater than

12 dB. At frequencies above 32 kHz, the omnidirectional response of the

system shall decrease with increasing frequency at a rate equal to or greater

than 12 dB per octave.

2.1.2 Amplifiers and Weighting Network

With an equivalent electrical impedance substituted for the microphone,

the internal noise of the entire system shall be the equivalent of 35 dB(A) or

less, and the equivalent of a 85 dB(A) signal shall produce less than 5%

harmonic distortion.

2.1.3. Clock

The self-contained clock shall have an inherent uncertainty of less than

36 seconds in 24 hours. The maximum total coast error, i.e., error due to

starting and stopping, shall be less than 36 seconds for a cycle of 10 seconds

on, 10 seconds off, over a test period of 24 hours. The clock shall cause the

monitor to sample the noise level every 2.2 milliseconds. The clock shall

stop the sampling after 24.00 + 0.01 hour.

2.1.4 Detector and Clock Gates

The RC time constant of the detector shall be .125 + .02 seconds.

The detector and gates which control the clock registers shall activate

the registers at the root-mean-square amplitudes of 45 + 0.5, 55 + 0.5, 65 +

0.5, 75 + 0.5 and 80 + 0.5 dB(A) for the following signals:

1. sinusoidal signal at 1 kHz.

2. Gaussian noise at any equivalent amplitude between 45 and 80 dB(A)

.

3. Tone burst having a frequency of 100 Hz and a duty cycle of 10%.

A separate gate (from that used to activate a clock register) shall be

used to activate the register indicating how many times the noise level

exceeded 80 + 0.5 dB(A) . This gate shall have a time constant of 10+1 sec.

2.1.5 Wind and Weather Screen

The microphone shall be provided with a weather shield and wind screen to

permit operation in inclement weather. This shield shall be such that the

equivalent noise is less than 55 dB(A) for winds up to 40 km (25 mph) and, in

the absence of rain, shall charge the sensitivity of the microphone less than

21
+1 dB over the frequency range 20 Hz to 10 kHz and less than +2 dB over the

Trequency of 20 Hz to 20 kHz. During rain at a rate up to 1.27 cm (0.5 inch)

per hour the sensitivity of the microphone shall be changed less than + 2 dB over the frequency range 50 Hz to 1 kHz and less than +3 dB over the frequency

range 1 kHz to 20 kHz.

A 10 cm (4 inch)* in diameter open cell polyurethane windscreen shall

also be provided. 2.1.6

Wind Sensor

The Monitor shall be equipped with a wind speed transducer sensor which

shall activate a clock register when the wind exceeds 40 + 10 km/hr (25 + 6

mph) . This shall be connected to the Monitor with a Military Standard MS3102E

connector

The windsensor, when subjected to a rain at a rate of 1.27 cm (0.5 inch)

per hour, but no wind, shall have a contact resistance of at least 100 k ohms.

2.1.7

Calibration and System Checkout

The Monitor shall include a separate acoustic calibration device which

shall have an acoustic output of 80.5 + .3 dB at a frequency of 1 kHz.

When the power is turned on, all memory in the Monitor shall be reset to zero. The Monitor shall be equipped with a switch-activated go/no-go indicator for

battery charge. For a go indication the batteries shall have sufficient

charge for powering the Monitor such that all specifications are met for 36

hrs. of continuous operation. The Monitor shall be provided with a means for

making up to 5 dB changes in amplifier gain. When the acoustic calibration

device is in place and activated, an indicator shall indicate one of the

following conditions: (1) gain is too small, (2) gain is correct, or (3) gain

is too large. Circuitry shall be provided to set an internal gate when the

Monitor is correctly calibrated to within +0.3 dB. The Monitor shall be

equipped with a "data-start" pushbutton and indicator. Data acquisition

cannot be started nor a data transfer made unless the following steps have

been performed in sequence: (1) power on, (2) battery check, and (3) valid

acoustic calibration has been performed.

The Monitor shall have circuitry to determine that, after 24 hours, a second calibration has been performed at 80.5 + 1.0 dB. If the calibration is

not within this tolerance, it shall not be possible for the Monitor to

transfer data to the Reader.

2.1.8

Memory Registers

For both indoor and outdoor applications, the Monitor shall store the

following information in digital form on internal memory registers:

an identification number (in permanent memory) unique to each

Monitor unit

22
the accumulated times (to the nearest 0.01 hr.) that the noise level

exceeded 45, 65, 75 and 80 dB(A), respectively, during the 24-hour

monitoring period

the accumulated time (to the nearest 0.01 hr.) that the noise level was less than 45 dB(A) during the 24-hour monitoring period.

For outdoor applications, the Monitor shall store the following

additional information in digital form on internal memory registers:

the number of times (to the nearest integer) that the noise level

exceeded 80 dB(A) during the 24-hour monitoring period

the accumulated time (to the nearest 0.01 hr.) that the wind speed

exceeded 40 km/hr.

For indoor applications, the Monitor shall store the following additional

information in digital form on internal memory registers:

the accumulated time (to the nearest 0.01 hr.) that the noise level

exceeded 55 dB(A) during the 24-hour monitoring period

the accumulated time (to the nearest 0.01 hr.) that the noise level

exceeded 45 dB(A) between 2300 and 0700 hours.

2.1.9 Power Supply

The Monitor shall be provided with its own power supply consisting of

rechargeable batteries (power pack) and sufficient power to enable 36 hour

operation. The battery power pack shall be constructed such that individual

cells may be replaced by the use of hand tools. The batteries shall be

located in a separate chamber which is tightly sealed from the chamber con- taining the electronic circuitry. However, the power pack shall be

constructed such that one cell may be replaced by using only hand tools. The

Monitor also shall be provided with a battery charger, as a separate unit,

which is capable of recharging the power pack from a fully discharged state to a fully charged state in a period of 14 hours. The battery charger shall

operate from normal 115V, 60 Hz, electrical lines.

The Monitor shall be designed so that the power pack batteries can be

changed readily. One extra battery pack shall be furnished with each Monitor

unit

.

The power pack provided with the Monitor shall, when fully charged,

enable operation for a period of 36 hours.

2.1.10 External Connections

The Monitor shall be provided with Military Standard MS3102E external
connectors for coupling to the Reader, and for connecting the microphone and

wind speed sensor to the Monitor.

2.1.11 Mechanical Specifications

The Monitor, including the power pack, shall have a volume of less than

.0071 in (0.25 ft; and weigh less than 3.63 kg (8 lb), exclusive of the wind

and weather shield for the microphone, and the mounting system.

The Monitor shall be contained in a case which meets or exceeds requirements of MIL-T945 specifications except Paragraph 3.51.2.4. All external

devices, such as wind sensor and microphone mounting system, shall be the same

color as the case. The lid of the case shall contain a clip for holding a screwdriver for gain adjustment of the Monitor. The mounting shall be

designed to minimize acoustical reflections from the fixed object and the

mounting device itself. The mounting shall be of such size and construction

that it can be used conveniently by one person. The mounting shall include

clamps for mounting to fixed objects, 7.62 to 30.5 cm (3 to 12 inches) in

diameter. These clamps shall be able to be interconnected for mounting to

'larger diameter objects.

To minimize chances of dropping the Monitor a shock cord, or cords, shall

be provided for temporarily attaching the Monitor to a fixed object 10 to 92 cm (4 to 36 inches) in diameter while clamps are being secured for a more

permanent mounting.

The Monitor shall include a goose neck 30 to 46 cm (12 to 18 inches) long

for mounting the Microphone to the case.

The Monitor shall be equipped with a polyethylene foam envelope 5 cm (2

inches) thick for covering the Monitor case. The envelope shall have cut-outs

for the Microphone and windscreen. This envelope shall completely cover the

Monitor and be equipped with a tape closure for fixing it to the case.

The power switch shall be enclosed by a cylindrical switch guard that

has a height that is 90% of the height of the power switch.

2.1.12 Environmental Specifications

Temperature and Humidity — The Monitor shall operate over the

temperature range -20 to +60 °C with a change in overall sensitivity of not more than +0.5 dB . The effect of changes in relative humidity on the response

of the Monitor shall be less than +0.5 dB in the range 5 to 90% R.H. The

Microphone shall be constructed of corrosion resistant materials such that a 60 day exposure to 100% relative humidity at 25 °C will change the frequency

response by less than 0.1 dB in the frequency range 20 Hz to 20 kHz.

Magnetic Field — With the microphone connected to the Monitor, a magnetic field strength of 80 ampere per meter in the frequency range 50 to

500 Hz shall produce the equivalent of no more than 30 dB(A) for any

24
orientation of the Monitor relative to the magnetic field.

\ Vibration — With a vibration-insensitive equivalent electrical impedance

substituted for the microphone, the effect of 1 sinusoidal acceleration along

each of three mutually orthagonal axes of the Monitor in the frequency range

63 to 4000 Hz, or of a shock load of 30 g's, 1/2 sine, 11 milli-second

duration, shall be less than the equivalent of 30 dB(A). The vibration

sensitivity of the microphone shall not exceed 100 dB (re 20 micropascals) at

any frequency in the range 63 to 4000 Hz for a 1 g sinusoidal acceleration

along each of three mutually orthagonal axes

.

With the Monitor enclosed in the polyethylene envelope, and the

Microphone and wind sensor removed, the Monitor shall not be damaged by a 4.57

m (15 foot) drop along each of three mutually orthogonal axes.

Airborne Noise — The Monitor, including the microphone and all

electronics, when in operation, shall not be damaged by continuous exposure to

airborne noise at a level of 140 dB(A) . When the Monitor is exposed to a pure

tone sound at any frequency over the range 10 to 20,000 Hz and at any level over the range 45 to 80 dB(A) , or when the Monitor is exposed to an octave

band of Gaussian noise at any center frequency in the range 63 to 8000 Hz, the

detected signal shall be at least 20 dB greater than that under the same conditions and in the same sound field when the microphone is replaced by an equivalent electrical impedance.

2.2 Reader Specifications

The Reader shall be a self-contained, battery-operated unit capable of

interrogating and providing a permanent record of data stored in the Monitor.

It shall include interconnections such that the Reader cannot be powered until

it is connected to the Monitor. The Reader shall include the necessary logic

to perform the following functions: (1) Calibration interrogation, (2) Monitor-malfunction interrogation, (3) data transfer. It shall include a read-start switch, a no-calibration indicator, a Monitor-malfunction

interrogation and a data- transfer-complete indicator. The Monitor-malfunction

interrogation shall be a check of the internal consistency of the data stored

in the Monitor.

When the read-start switch is activated, the Reader shall produce, on an internally-contained printer, hard copy indicating one of the following three

situations:

1. Unsatisfactory calibration

2. Monitor-malfunction

3. Data transfer complete.

If data transfer is effected, the Reader shall then produce, on its printer,

the following data as transferred from the Monitor:

25
1 . The accumulated time that 80 dB (A) was exceeded

2. The accumulated time that 75 dB (A) was exceeded

3. The accumulated time that 65 dB (A) was exceeded

4. The accumulated time that 45 dB(A) was exceeded

5. The number of times 80 dB(A) was exceeded.

6. The accumulated time the wind was greater than 20 knots.

7. The Monitor identificationi number.

During indoor applications, with the Time of Day clock connected,

accumulated time that 45 dB(A) was exceeded between 23:00 and 07:00 hours

shall be transferred instead of the number of times 80 dB(A) was exceeded, and

the accumulated time that 55 dB(A) was exceeded shall be transferred instead

of the total time the wind speed was greater than 40 km/hr.

The Reader shall print a unique symbol at the beginning and end of the

data in order to minimize the possibility of falsification of data.

2.2.1

Reader Accuracy

The Reader shall print out all times to the nearest 0.01 hr. and the

number of times 80 dB(A) was exceeded to the nearest integer.

2.2.2

Printer

The printer shall consist of at least a 5 x 5 matrix and produce easily

readable hard copy while the Reader is in any orientation.

2.2.3

Power Supply

The Reader shall be provided with its own rechargeable power pack and

suitable voltage control. The batteries shall be located in a separate

chamber which is tightly sealed from the chamber(s) containing the electronic

circuitry and the printer. The Reader shall be provided with a battery

charger, which is capable of recharging the power pack from a fully discharged

state to a fully charged state in a period of 14 hours. The batteries shall

not have to be removed for charging. The battery charger shall operate from

normal 115V, 60 Hz, electrical lines.

The Reader shall be provided with an indicator to determine the state of

charge of the power pack is sufficient to enable the Reader to interrogate the

Monitor two times.

The power pack provided with the Reader shall, when 80 percent charged.

26
enable 10 Monitor interrogations to b,e effected without necessity for

recharging at a temperature of 5°C.

2.2.4

External Connections

The Reader shall be provided with a Military Standard MS3102E connector

for coupling to the Monitor. The Reader shall use the same connector for

battery recharging. 2.2.5

Mechanical Specifications

The Reader, including the power pack, shall occupy a volume of less than

.014 in (0.5 ft) and weigh less than 4.53 kg (10 lb).

2.2.6

Environmental Specifications

Temperature and Humidity — The accuracy or functional capabilities of

the Reader shall not be affected by temperatures in the range of 0 to 60 °C or relative humidity in the range of 5 to 100% R.H.

Rain — The Reader shall be enclosed such that it will not be damaged in

a rain storm of 10 cm (4 inch) per hour.

Magnetic Field — With the Reader connected to the Monitor, a magnetic field strength of 80 ampere per meter in the frequency range 50 to

500 Hz shall not affect the accuracy or functional capabilities of the Reader.

Vibration — The operation of the Reader shall not be affected by a 1 g

sinusoidal acceleration along each of three mutually orthogonal axes of the

Reader in the frequency range of 63 to 4000 Hz, or by a shock load of 30 g's,

1/2 sine, 11 milli-second duration.

2.3 Time of Day Clock Specifications

The Time of Day clock shall be a self-contained, battery-operated unit

capable of providing the necessary logic to the Monitor to enable the 45 dB(A)

memory register between 2300 and 0700 hrs . The clock shall include provisions

for setting units of minutes, tens of minutes, units of hours and tens of

hours

.

2.3.1 Clock Accuracy

The clock shall have an uncertainty of less than 36 seconds in 24 hrs.

2.3.2 Time Readout

The time readout shall be of the 24:00 hrs. type. The display shall be

of the segmented type such that a failure of one element cannot be read as a different number; e.g., an "8" cannot be read as a "6" or "9" due to failure

of one element of the display. To conserve battery power the display shall

27
only be powered during setting of the time of day.

2.3.3

Power Supply

The clock shall be provided with its own rechargeable power pack and

suitable voltage control. The batteries shall be located in a separate

chamber which is tightly sealed from the chamber(s) containing the electronic

circuitry. The clock also shall be provided with a battery charger, which is

capable of recharging the power pack from a fully discharged state to a fully

charged state in a period of 14 hours. The batteries shall not have to be

removed for charging. The battery charger shall operate from normal 115V, 60

Hz, electrical lines.

The clock shall be provided with an indicator to determine that the state

of charge of the power pack is sufficient to power the clock for 24 hours.

The power pack provided with the clock shall, when 80 percent charged,

enable 36 hours of operation.

2.3.4

External Connections

The clock shall be provided with a connector to mate with the Monitor.

The clock shall also be provided with a connection to mate with the Reader

such that the clock need not be disconnected for the Reader to interrogate the

Monitor

.

2.3.5

Mechanical Specifications

The Reader,, including the power pack, shall occupy a volume of less than

5.66 cc (0.2 ft ) and weigh less than 1.36 kg (3 lb).

2.3.6

Environmental Specifications

Temperature and Humidity — The accuracy of functional capabilities of

the clock shall not be affected by temperatures in the range of 0 to 60 °C or relative humidity in the range of 5 to 100% R.H.

Magnetic Field — With the clock connected to the Monitor, a magnetic

field strength of 80 ampere per meter in the frequency range 50 to 500 Hz

shall not affect the accuracy or functional capabilities of the clock.

Vibration — The operation of the clock shall not be affected by a 1 g

sinusoidal acceleration along each of three mutually orthogonal axes of the

Reader in the frequency range of 63 to 4000 Hz, or by a shock load of 30 g's

1/2 sine, 11 milli-second duration.

2.4. Transit Case

The system shall include a Transit Case. The Transit Case shall include

provisions for shipping the following items:

28
(1) Monitor with Microphone and Mounting Device

(2) Calibration Device

(3) Wind Sensor

(4) Battery Chargers

(5) Reader

(6) Windscreens

A carrying case shall be provided for transportation of the mounting

tools and materials.

2.4.1 Mechanical Specifications

The Transit Case shall be of a size and dimensions that it may be shipped

as luggage by all domestic airlines.

The case shell shall be constructed of deep drawn 2024 aluminum alloy,

heat treated at least 100 mm (.040 inch) thick. The closure for the case shall be interlocking tongue and groove extrusion of 6063-T5 aluminum alloy

bonded to case, and shall include a neoprene gasket seal. The case hinge

shall be of the piano type (continuous) aluminum and riveted to the case. Case latches shall be positive locking bale. The case shall be lined with (2

lbs) polyurethane foam with cutouts for the items contained therein.

2.4.2 Environmental Specifications

Rain — The Transit Case shall not leak water when subjected to a rain of

10 cm (4 inch) per hour.

Vibration — The contents of the Transit Case shall not be damaged when

dropped 3 m (10 feet) along each of three mutually orthogonal axes of the case.

29
.

'

.
7. APPENDIX B

HUD'S NOISE

MEASUREMENT

SYSTEM

CAUTION: The microphone is a delicate

instrument and you are cautioned to avoid bumping or dropping it. The windscreen should be kept over the microphone to avoid damage.

PREPARATION IN THE OFFICE

This section contains instructions for an inventory check of parts needed for

mounting, and for checks of batteries

and damage to the windsensor. These

checks should be performed in the office

prior to leaving for the site.

Inventory Check

For mounting the system, check to see if you have the following parts:

1. Monitor

2. Calibrator

3. Windscreen

4. Windsensor

5. Banding Material*

6. Buckles*

7. Banding Tool*

8. Hammer*

9. Polyurethane Cover

1CL Tape*

11. Shock Cord

‘ Items not shown in illustration.

t

FIGURE 1

30
Microphone Check

Look into window of microphone dessi cator and check color of powder of the

dessicator. If it has turned from blue to

light pink, the dessicator must be baked.

See MAINTENANCE.

Monitor Battery

When not in use, one of the Monitor

batteries should be charged. To charge

the battery, connect it to the Monitor

Battery Charger. Connect the charger to an ac outlet and then turn it "ON". The

battery should be charged a minimum of

14 hours. The battery cannot be over- charged.

Monitor Battery Check

1.

Open the Monitor case by pulling on

the two case latches.

WARNING: These latches are spring

loaded. Be sure to keep your fingers

out of the way.

2. Turn the POWER "ON".

3. Depress the BATTERY CHECK

pushbutton. If the green light to the

left of the "BATTERY CHECK" is on, the batteries are charged. If not,

do the following.

a. Turn the POWER "OFF".

b. Remove the two wing screws next to the handle below the

pushbuttons and place them in the case lid. c. Remove the "BATTERY" case by pulling straight out on the

handle while holding the Monitor case.

d. Insert a new "BATTERY" by

pushing down on the handle.

NOTE: The "BATTERY" label should be facing the switches.

Check the battery by going to Step 2. If this battery fails the

battery check test, both batteries need to be charged.

31
Calibrator Battery Check

Unsnap the top leather cover of the

acoustic calibration device and depress

and then release the pushbutton on the

side. You must hear a tone, and this tone

should last at least 45 seconds to indi- cate adequate charge. If not the battery

must be replaced with a new 9 volt

transistor radio battery available at most

drug stores. Use the following procedure.

1. Remove the leather cover from the

calibrator.

2. Unscrew the bottom battery cover. This cover is on the opposite end

from the opening.

3. Unsnap the battery terminals and

replace the battery.

4. Recheck the battery. If the battery

does not pass the battery check,

recheck the connections.

5. Assemble the battery cover and the

calibrator cover.

Windsensor Check

Visually check the windsensor for dam

age by gently pushing the ball to the

sides of the tube to see that the shaft is not binding against the sides of the tube.

CAUTION: If the shaft is binding against

the sides of the tube, the windsensor is damaged and the data obtained from the

NMS will not be valid.

TUI

WINDSENSOR

FIGURE 3

32
CALIBRATION

This section contains the instructions for

calibration of the Monitor. If the time

required to reach the site is 2 hours or

less, this may be performed in the office.

(See Figure 4 for the location of controls.)

1. Open the Monitor case.

2. Turn the POWER "ON".

3. Depress the "BATTERY CHECK"

button. If this light is on, proceed.

If not, change the battery.

4. Remove the windscreen. Place the

calibrator over the microphone and

push it down.

5. Depress and then release the pushbutton on the calibrator.

NOTE: If the operations below take

more than 45 seconds, the pushbutton must be depressed again

since the calibrator will turn itself off.

6. Depress the CAL ENABLE pushbutton. Hold the button in the

depressed position. If a red light

goes on, continue to depress the

CAL ENABLE button and turn the

calibrator adjust screw in the indi- cated direction until the center

green light goes on. NOTE: If the screw has been turned

twenty turns and the center light is not on, check to see that the calibra- tor is still on.

7. Depress the CAL SET pushbutton.

The green light will come on if step

6 has been performed successfully,

and the calibrator is still on.

8. Remove the calibrator and replace

the windscreen.

FIGURE 4

33
MOUNTING

This section contains instructions for

mounting the Monitor, at the site. The

Monitor is designed to be mounted on a utility pole or other pole and secured

according to instructions on banding

material box for use of banding material.

If a utility pole is not used, see the

Appendix for instructions.

1. Cut band 5 inches longer than the

distance around pole. Thread band

through buckle for at least % in. and

bend band back under buckle. Cut

the band using the front handle on

the tool.

2. Thread the band through the slots in the foam cover and through both

loops on the back of the Monitor.

3. With the microphone pointing up, temporarily clamp the Monitor in position with the shock cord. The

cord should pass through the handle.

4. Clamp the Monitor to the pole by

turning the handle.

CAUTION: Turn the handle until

the polyurethane cover has just

started to deform. BE CAREFUL

NOT TO DEFORM THE METAL

CASE.

5. Rotate tool over buckle, backing off

gradually with tension handle

through entire course of bend. Cut

any surplus material.

6. Mount the windsensor by plugging it in the connector and turning it to the right.

7. Move the microphone away from

the pole by bending the goose neck

as shown in Figure 6.

8. Remove the shock cord and depress

the DATA START pushbutton.

When the Data Start Light turns on, data collection has started. If the

green light does not go on, repeat

the calibration procedure.

9. Close the cover and place the second

half of the polyurethane cover over

the Monitor. Secure the cover with

tape all around the cover. Do this as quietly as possible.

This completes the mounting of the

Monitor. It will collect data for the next

24 hours and then stop automatically.

Data cannot be read before the 24 hour

collection period, or after 36 hours.

At this time you should check the

Reader batteries. See next page. If the

batteries require charging, do so at this

time.

FIGURE 6

34
PREPARATION

FOR DISMOUNTING

THE MONITOR AND

READING THE DATA

WARNING: Do not turn Monitor power

off prior to completion of reading the

data.

This section contains instructions for an

inventory check of parts needed for

dismounting the Monitor and reading the

data and for checks on batteries in the

Reader and Calibrator. These checks

should be conducted in the office before

leaving for the site. Remember, data

from the Monitor cannot be read prior to 24 hours. Any attempt to read the

Monitor prior to completion of the full 24 hour period will result in a meaningless zero answer. Data must be read

before 36 hours have elapsed from the

instrument turn on time.

Inventory Check

To remove the Monitor and read the

data, check to see that you have the

following:

1. Cutters

2. Shock Cord

3. Calibrator

4. Reader

Battery for the Readers

NOTE: The battery for the Manual

Reader and Automatic Reader is contained in the case and cannot be re- moved.

Manual Reader

The Manual Reader Battery should be

charged. To charge do the following:

a. Turn the Reader Switch OFF.

b. Connect the Reader to the Reader

Battery Charger.

c. Plug the charger into an "ac" outlet.

The Reader must be charged a minimum of 14 hours; it cannot be

overcharged.

To check the charge in the Manual

Reader:

1. Turn the POWER of the Manual

Reader “ON”.

2. If the red light below “COUNTER

NUMBER" comes on, the battery

has sufficient charge to interrogate

the Monitor.

3. If the red light below “COUNTER

NUMBER" does not come on, the

battery must be charged.

35
Automatic Reader Manual Reader

The battery for the Automatic Reader

should be charged after ten interroga

tions of the Monitor.

To charge:

a. Connect the Automatic Reader to the Reader Battery Charger.

b. Turn the Reader Power "OFF" and

the Charger Power "ON".

c. Plug the Charger into an "ac” outlet

for a minimum of 14 hours. The

battery cannot be overcharged.

To check the charge in the Automatic

Reader:

1. Turn the POWER switch of the

Automatic Reader to "TEST".

2. If the red light on the Automatic

Reader comes on, the battery has

sufficient charge to interrogate the

Monitor.

3. If the red light does not come on, the battery must be charged.

READING THE DATA

This section contains instructions for

reading the data. Separate instructions

are provided for the Manual Reader and

the Automatic Reader.

WARNING: DO NOT TURN THE MON

ITOR POWER "OFF". If the power is turned "OFF" the data will be lost and a new measurement will have to be made.

READ OUT

"If the cdl set light does not come on, check to see

that the calibrator is working. If it is, the Monitor is defective and the data cannot be read.

1. Remove the polyurethane cover, temporarily clamp the Monitor with

the shock cord, remove the wind

sensor, and then remove the Mom

tor from pole.

2. Open the lid and connect the

Reader to the Monitor, and turn the

Reader Power "ON".

3. Remove the windscreen, place the

calibrator over the microphone and

push it down until it seats over the

microphone.

WARNING: DO NOT depress the

Cal Enable button on the Monitor.

4. Depress the pushbutton on the call brator and then depress the "CAL

SET" pushbutton. The cal set light

will come on.

5. Depress the data transfer push

button and release it. Record the

data and counter number. Check to see that this number is correctly

recorded. When the pushbutton is depressed again, the counter will be

reset. Depress the pushbutton again

and data for the next counter will be shown. Repeat this operation for

all 8 encounters.

6. Turn the power to both units

"OFF", disconnect them and re place the windscreen.

The register and the data are displayed as follows:

Counter Interval (Decimal hours)

1 Greater than 80 d B ( A

)

2 75-80 dB(A)

3 65-75 dB(A)

4 45-65 dB(A)

5 Less than 45 dB(A)

6 Number of events over 80 dB(A)

7 Time that wind noise ex ceeded capability of

windscreen

8 Serial number of Monitor

(Sequential addition of counters 1 through 5 is necessary before this data

conforms to the format of HUD General

Noise Standards.)

The data is in decimal hours, not min

utes. To verify the data, total counters 1 through 5; the total must be 24 + .05 oi the system has malfunctioned.

36
AUTOMATIC READER

The Automatic Reader interrogates the

Monitor, performs checks on the status of the Monitor and prints out the data.

1. Remove the polyurethane cover, temporarily clamp the Monitor with

the shock cord, remove the windsensor and remove the Monitor from

the pole.

2. Open the lid and connect the

Reader to the Monitor. Turn the

Reader Power "ON”.

3. Remove the windscreen, place the

calibrator over the microphone and

push it down until it seats over the

microphone.

WARNING: DO NOT depress the

Cal Enable button on the Monitor.

4. Depress the pushbutton on the cali- brator and then depress the "CAL

SET" pushbutton. The cal set light

will come on.*

5. Turn the power "ON”. It will take

the Reader approximately one min

ute to check the data during which

time the only indication it is working is the pilot light will be on.

6. The Reader will print data as fol- lows:

The Reader first checks to see that a calibration was performed. If the

system was not calibrated, "UC” is printed and the measurement must

be repeated. The Reader then

checks the rest of the Monitor, if a failure in the Monitor occurred in the 24 hour data collection period, a "MM” (Monitor Malfunction) is printed. If the system is operating

correctly and was used correctly,

data is printed in the following

sequence:

Counter

1 Monitor serial number

2 Time greater than 80 dB(A)

3 Time greater than 75 dB(A)

4 Time greater than 65 dB(A)

5 Time greater than 45 dB(A)

6 Number of events greater than

80 dB(A)

7 Time that wind noise ex- ceeded capability of windscreen The data as printed by the Reader is in decimal hours.

7.

After the data are printed, turn the

power to both units "OFF”, discon

nect them and replace the wind

screen over the microphone.

*lf the cal set light does not come on, check to see that the calibrator is working.

FIGURE 9

FIGURE 10

37
MAINTENANCE APPENDIX

The NMS requires little user mainte- nance beyond charging batteries.

The precision microphone, however, in this system can be affected adversely by

high humidity. A dessicator, containing a water absorbing material, is attached to the microphone to keep it functioning

properly. Periodically, the dessicator

must be dried out by baking it in order

to restore its effectiveness. The fre- quency that the dessicator must be

baked will depend upon the relative

humidity to which the Monitor is ex- posed. In very high humidity conditions,

the dessicator should be checked after

72 hours of use. To check, remove the

windscreen and look at the color of the

powder through the small window. If the

color has changed from blue to light

pink, the dessicator must be baked.

WARNING: DO NOT DEVIATE FROM

THE FOLLOWING INSTRUCTION.

Any deviation will most probably destroy the microphone or dessicator. Not

only would replacement be expensive, a replacement may take as long as 6 to 9

months. If there are any questions, do

not attempt to bake the dessicator.

To bake the dessicator CAREFULLY

use the following procedure:

1. Grasp the microphone just below

the black plastic grid and unscrew it while holding the dessicator, place

the microphone in a safe place.

2. Unscrew the dessicator.

3. Place only the dessicator in an oven

heated to 200° F for 6 hours or more.

To assemble the units CAREFULLY use the following procedure:

1. Screw on the dessicator.

2. Grasp the microphone below the

plastic grid and screw it on the

dessicator.

v If a utility pole is not used, a fence post

and auxiliary pole must be used.

1. Drive the fence post in the ground

until the barbs on the bottom of the

pole are just covered.

2. Place the auxiliary pole over the

fence post.

3. Push the mounting bolt through the

hole in the auxiliary pole and hole

in the fence post.

4. Screw the bolt into the nut and go

to step 1 of Mounting.

38
.

_

.
8. APPENDIX C

FIELD USE INSTRUCTIONS

THE HUD NOISE MEASUREMENT SYSTEM

39
INTRODUCTION

This manual provides information for the

utilization of the HUD Noise Measurement

System. It is a companion to the

document entitled Operation Instructions

the HUD Noise Measurement System. This

system was developed to assist HUD in

implementating its policy on noise

abatement and control for general sites

which are not impacted by airport noise.

Sites for HUD sponsored development must

comply with, the noise exposure standards

contained in HUD Policy Circular 1390.2.

In order to implement the standards , HUD

Noise Assessment Guidelines were

developed to enable personnel without

acoustical training to perform

preliminary estimates of the noise

exposure of a site in relation to the

KUD standards . The Guidelines are

designed to be used as a screening

device to indicate whether proposed

sites may be exposed to excessive noise

levels. When the use of the Guidelines

indicates a potential noise problem In

need of further resolution, it is wise

to supplement existing information with

actual noise measurements on the site.

The Noise Measurement System when used

in accordance with the directions

provided in the present manual will

provide accurate data on the existing

noise exposure of a site in accordance

with HUD's General Noise Exposure

Standards

.

To facilitate the use of the present

document, a brief summary of HUD Interim

Standards are included in Table I. Note

that only general exposure of sites

which do not lie within a zone impact, by

airport noise are Included since the

present system is especially designed

for general purpose only.

A brief summary is presented in the form

of a flow chart in Table IT which

condenses the various steps involved in

obtaining data with the HUD Noise

Measurement System. . This is then

followed by a detailed step by step

procedure for obtaining and interpreting

the data from the HUD Noise Measurement

System.

Where appropriate, examples are given on

the right hand side of the page in

italic typeTABLE I

EXTERNAL NOISE EXPOSURES FOR NEW RESIDENTIAL CONSTRUCTION

IN A-WEIGHTED SOUND PRESSURE LEVELS -

UNACCEPTABLE

Exceeds 80 dB(A). 1.00 hour per 2b hours

Exceeds 75 dB(A) 8 hours per 2h hours

DISCRETIONARY — NORMALLY UNACCEPTABLE

Exceeds 65 dB(A) 8 hours per 2b hours

Loud repetitive sounds on site

DISCRETIONARY — NORMALLY ACCEPTABLE

Does not exceed 65 dB(A) more than 8 hours per 2b hours

ACCEPTABLE

Does not exceed U 5 dB(A) more tiffin 0-50 hours per 2b hours
TABLE II FLOW CHART OF OPERATIONS

41
FINDING THE APPROPRIATE LOCATION AND

MOUNTING THE MONITOR • •'

STEP 1

Identify the “best location for the

Monitor according to the following

procedure:

1.

a. Walk around the site and listen

for the noisiest location. Listen for

traffic noise, truck-car mixture , stop

and go traffic , and other sources of

noise. If more than one point is found

or the site- is large, more than one

measurement point may he appropriate.

STEP 2

In order to mount the Monitor you will

need to refer to the OPERATING

INSTRUCTIONS THE HUD NOISE MEASUREMENT

SYSTEM.

2.

a. If there is a utility standard at

the location Identified in Step l.a.

refer to the OPERATING INSTRUCTIONS -

PREPARATION IN THE OFFICE and THEN

MOUNTING. If there Is no utility

standard go to Step 2.c.

2.b. Draw a plan view of the site on

the hack of the data sheet. Indicate

major noise sources and the location of

the Monitor.

2.

c. If there is no utility standard at

the location identified in Step l.a.

refer to the OPERATING INSTRUCTIONS -

‘ APPENDIX for instructions- on erecting a

pole and then go hack to 2. a.

READING THE DATA -4

STEP 3

In order to read the data refer to the

OPERATING INSTRUCTIONS THE HUD NOISE

MEASUREMENT SYSTEM. If the system

contains an Automatic Reader go to Step

3.

a. If the system contains a Manual

Reader go to Step 3.b.

3. a. Refer to the OPERATING

INSTRUCTIONS - READING THE DATA - AUTOMATIC READER, read the data from the

Monitor and place the data tape on the

Automatic Reader Data sheet.

3.b. Refer to the OPERATING

INSTRUCTIONS - READING THE DATA - MANUAL

READER, read the data from the Monitor

and enter these data in the Manual

Reader Data Sheet.

VALIDATING THE DATA

STEP 4

The data must he validated for correct

operation of the Monitor and the time

that the wind noise exceeded the

capability of the windscreen. In the

case of the Automatic Reader only the

latter check must he performed. If the

system contains an Automatic Reader go

to Step U.a. If the system contains a

Manual Reader go to step U.b. then U.c.

U.a. Determine that the wind noise did

not exceed the performance of the

windscreen by checking that the wind

noise counter is less then 1.00, if

greater than or equal to 1.00 the test

must he run again; therefore go hack to

Step 2. If less than 1.00 go to Step 5*

U.h. Determine that the Monitor

operated correctly in the 2U hour period

by summing counters 1 through 5 and

determine that this sum is between 23*95

and 2U.05-

U.c. Determine that the wind noise did

not exceed the performance of the

windscreen by checking that counter 7 is

less than 1.00 if greater or equal to

1.00 the test must he run again;

therefore go hack to step 2. If less

than 1.00, go to Step 5-

STEP 5

5. a. If the Monitor was mounted at the

noisiest location AND future noise need

not he predicted complete the data sheet

and then go to step 15-

42
5-b. If neither of the two conditions

stated in 5- a. are met, then enter the

data from the Manual or Automatic Reader

Data sheet into Worksheet 1 to convert

the data into a usable form for the

following steps.

PLOTTING DATA

STEP 6

6. a. Convert the time that all four

levels were exceeded into percentage of

a day by multiplying the time by 100$

and then dividing this result by 2h.

Enter the results in Worksheet 1.

6.b. Plot the results of Step 6. a. on

the graph paper contained in Figure 1,

Graph Paper for Adjusting Data.

EXAI-1PLE FOR STEP 6 A PD 7.

Example l

In this example the following data was

obtained from the reader : Time that 80

dB(A) was exceeded 0.20 hours

Time that 75 dB(A) was exceeded 1.15

hrs.

Time that 65 dB(A) was exceeded 8.65

hrs.

Time that 45 d3(A) was exceeded. 22.55

hrs.

The results of converting these data

into percentage of a day are:

Percentage of day that 80 dB(A) was

exceeded 0.83

%

Percentage of day that 75 dB(A) was

exceeded 4.79

%

Percentage of day that 65 dBCA) was

exceeded 36.0%

Percentage of day that 45 dB(A) was

exceeded 98.1

%

The data is shown plotted in the

following figure.
STEP 7

Example 2

Draw a smooth curve through the

points plotted in Step 6. b.

ADJUSTING DATA FOR LOCATION

STEP 8

The following steps are used to adjust

the data for distance when the Monitor

could not he mounted at the appropriate

location. If the Monitor was mounted at

the appropriate location go to Step 9*

8. a. Determine the distance from the

desired location to the noise source and

enter this distance on Worksheet 1

8.b. Determine the distance from the

actual location of the Monitor to the

noise source and enter this distance on

Worksheet 1.

8.c. Divide the distance found in Step

8. a. by the distance found in Step 8.b.'

and enter this ratio on Worksheet 1.

8.d. Find the correction in Table III

for the distance ratio found in Step

8.c. Enter this correction on Worksheet

1 .

8.e. If future noise must be predicted

go to Step 9> if not go to Step 13-

PREDICTING FUTURE NOISE

STEP 9 - V.

Before beginning the evaluation, you

should try to obtain any. available

j nfo.r-rvtion about approved plans for

road changes . You will need to make

adjustments for the following changes:

oTraffic volume

oRoad gradient of 3 or more

oTraffic controls

oMean speed

oBarriers

If the only change is in traffic volume

go to Step 10. If other changes are to

be made go to Step 11.

In the following figure the data plotted

in Example 1 has a smooth curve drawn

through the data points.

Example of curve fitted through the data

points.

EXAMPLE FOR STEP 8.

Example 3

The site shown below is exposed to noise

from one major road.

The distance from the desired location

to the major noise source, in this case

a highwayj is 15 feet. The distance

from the highway to the location of the

Monitor is 20 feet. The ratio of the

desired location to the actual location

is .75. The correction from Table III

is -h 2 dB.
I Table III. Corrections for Distance. ' If correction is greater than +3 or less

than -3, and more than one noise source can be identified, professional

help may be required.

Distance Ratio Correction rtB

10

8

7

6

5

4

3

' 2.5

2

1.6

1.4

1.25

1.2 to .85 requires no correction

.8

.7

.6

• 5

.4

.3

.25

.2

.15

.12

.11

.10

-15

-l4

-13

-12

-10

- 9 - 8 - 6 - 4 - 3 - 2 - 1

+ 1

+ 2

3

4

6

6

9

10

12

13

14

15

45
STEP 10

If the only change is in traffic volume

use the following steps.

10. a. From the City (County) Director

of Traffic obtain the peak traffic flowin both directions, combined, and enter

this number on Worksheet 1.

10. b. From the same source used in Step

10. a. determine the expected traffic

flow for the next 10 to 15 years , and

enter this number on Worksheet 1.

10. c. Divide the flow obtained in Step

10. a. by the flow obtained in Step 10 .b.

and enter this ratio on Worksheet 1.

10. d. Use Table XY to find the

adjustment for the ratio found in Step

10. c. Enter the correction on Worksheet

1. Then go to Step 13-

STEP 11

If changes other than traffic volume

will occur you must use the following

steps . Before doing this , complete the

ROADWAYS evaluation pages 6 through. 13

contained in HUD NOISE ASSESSMENT

GUIDELINES for both Truck and Auto

traffic, and for both present and future

conditions. Upon completion of this

evaluation you will have Figure 2 from

the Guidelines for Hourly Automobile

Flow with two reference points , one

reference point for present traffic

conditions and one reference for future

traffic conditions. You will, also have

Figure 3 from the Guidelines for Hourly

Truck Flow with two reference points.

Do not proceed until you have completed

the evaluation and have obtained the two

figures and reference points . -

In this example the traffic will he

reduced due to a route cJiange. The

present peak hourly flow is 1000

vehicles per hour. The future peak

hourly flow is estimated as 250 vehicles

per hour. The ratio of present traffic

flow to future traffic flow is 4> and

the adjustment from Table IV is -6 dB.

EXAMPLE FOR STEP 11 AND 12.

Example 5

In this example, traffic volume> mean

speed and road gradient have been

changed . The ROADWAY evaluation of the

EUD NOISE ASSESSMENT GUIDELINES have

been completed for change in traffic

volume, mean speed and road gradient for

both present and future traffic. As a

result of the evaluation the following

two figures have been completed.

Example of how Figure- 2 .of the Noise

Assessment Guidelines is used to - establish reference points and

distances.

46 Example of how Figure 3 of the Noise

Assessment Guidelines is used to
• Table iv . Adjustment lor Changes m hourly

Traffic Flow.

Ratio of Future to Present x Hourly Traffic Flow Adjustments dB

10

8

7

5

h

3

2

1.5

1.25

1.2 to .7 requires no correction

.8

.6

.5

.3

• 25

.2

.15

.12

.1

-10

- 9 - 8 - 7

- 6

- 5 - 3 - 2 - 1

11. a. Perform Steps 11. b. through 11. f.

for the following four reference points.

oPresent hourly automobile flow

oFuture hourly automobile flow

oPresent hourly truck flow

oFuture hourly truck flow

11. b. Draw a line through the reference

point such that the line is

perpendicular to the upper boundry of

the clearly acceptable category and the

lower boundary of the clearly

unacceptable category. These boundaries

may have to be extended in order that

the lines drawn can intersect a boundary.

11. c. Measure the length of the line

drawn in Step 11. b. and enter this

length in Worksheet 2..

11. d. Measure the distance from the

reference point to the clearly

acceptable category line and enter this

distance in Worksheet 2.

1

2

3

5

6

7

8

9

10

The length of the two lines between

categories are 4.25" and 4.6" for the

present and future traffic. The

distance from the clearly acceptable

boundary to the reference points are 1"

for the present Traffic and 4.3" for the

Future Traffic. Thus, to find the

weighting for present traffic we divide

1" by 4.25" and then multiply the result

by 30. The result of this calculation

yields 7.0. For Future Traffic the

calculation yields 27.6. The difference

between the two is 20.6. Performing the

same calculation for trucks yields 19.5

for present traffic and 26.3 for future

traffic. The difference is 9. We next

compare the difference between the

future truck traffic and future

automobile traffic. The difference is

. 7 and therefore we must make a

correction. From Table V. the

correction is 2.5. This must be added

to the correction factor with the

largest weight. In this case the Future

Truck has a weighting of 28.3 so we add

2.5 to 9 yielding a final correction of

11.5.

47
11. e. Divide the distance obtained in

Step 11. d. by the length obtained in

Step 11. c. and enter this weighting

number in Worksheet 2.

11. f. Multiply the ratio obtained in

Step 11. e. by 30 and enter the result in

Worksheet 2.

11. g. Repeat Step 11. b. through 11. f.

for all four reference points.

11. h. Subtract the present automobile

weighting number from the future

automobile weighting number obtained in

Step 11. f. and enter the difference in

Worksheet 2.

11. i. Subtract the present truck

weighting number from the future truck

weighting number and enter the

difference In Worksheet 2.

STEP 12

Before the adjustment for effects of

future noise can be determined the

following operations must be performed.

oDetermine if the adjustment for

changes in automobile and truck traffic

volume need to be combined.

oDetermine which, adjustment should

be used.

To accomplish the above use the

following steps.

12. a. Subtract the smallest correction

found in Step 11. f. for future noise

from the largest correction found in

Step 11. f. for future noise. If the

difference is greater than 6 enter the

largest correction found in Step 11. h.

or 11. i. in Worksheet 2 as the final

correction then go to Step 13. If the

difference is 6 or less enter this

difference in Worksheet 2, then go to

Step 12. b.

12.b. If the difference found in Step

12. a. is 6 or less find the correction

in Table V and add this correction to

the difference (Step 11. I. I associated

with the largest number found in Step

11. f. Enter this number as* the final

correction in Worksheet 2.

Table V. Adjustments when Differences are Less than 6.

' Difference Adjustment dB

0

1

2

u

6

3

2.5

2

1.5

1

48
STEP' 13

This step combines the adjustment for x distance and the correction for future

traffic changes. If only adjustments

for distance were made, or only future

traffic changes were made, enter the

results of Step 8.d. for distance

adjustment or the results of Step 10. c.,

12.

a. or 12. h. for traffic changes as the shift factor in Y/orksheet 3 and go

to Step 1^.

13.

a. If both adjustments for distance

and prediction for traffic changes are

made add the results of Step 8.d. and

Step 10. c., 12. a., or 12. b. and enter

this sum as the shift factor in

Y/orksheet 3. In performing this

addition you are cautioned to observe

the signs on the two numbers.

STEP 1*+

The curve drawn in Step 7 should be

shift by the shift factor found in Step

13. Shift the curve up for a positive

correction and down for a negative

correction.

FINAL RESULTS

STEP 15

I If no adjustments were made to the data

check the category on Y/orksheet 3. Use

the levels indicated in Table T for

determining acceptability of the site.

If adjustments were made use the

following steps.

15. a. Find the percentage of time that

80, 75, 65 and U5 dB(A) was exceeded.

Note that the projected curve will haveto be extended to find the percentage of

a day corresponding to 1390*2. Policy

circular 1390.2 is given in Table VI in

terms of percentage of a day.

15. b. Use the levels indicated in Table

I for determining acceptability of the

site.

Example 6

In this we will develop shift factors

for some of the examples . Suppose that

the Monitor was not mounted at the

desired location hut was mounted as described in Exarrple 3. Additionally3 traffic volume will change as described

in Exarrple 4. The corrections for these

two examples were +2 and -6 dB. ThuSy

the shift factor is -4 dB.

Suppose that the Monitor was mounted at

the desired location and the traffic

conditionsy described in Example 5, were

used. Then the shift factor is 11.5.

EXAMPLE FOR STEP 14.

Example 7

In this example we will use the last

shift factor found in Example 6. Recall

that this shift factor was 11.5. The

shifted data is shown in the following

Figure.

Example of shifted data.

Notice that 80 dB'CA) is exceeded 21% of

24 hours. This is greater than 4 . 17%*

which is 60 minutes. Thusy the site is

unacceptable. Additionally * 75 dB(A) is

exceeded 46%* which is greater than 33%

which is 8 hours* which would make the

site unacceptable.

49
TABLE VI

EXTERNAL NOISE EXPOSURES FOR NEW RESIDENTIAL CONSTRUCTION

IN A-WEICHTED SOUND PRESSURE LEVELS

UNACCEPTABLE

Exceeds 80 dB(A) U.2$ of a day

Exceeds 75 dB(A) 33% of a day

DISCRETIONARY — NORMALLY UNACCEPTABLE

Exceeds 65 dB(A) 33$ of a day

Loud repetitive sounds on site

—DISCRETIONARY 1 —' NORMALLY' ACCEPTABLE - L i Does not exceed 65 dB(A) more than 33$ of a day

ACCEPTAELE

Does not exceed U 5 dB(A) more than 2.1$ of a day

50
9. APPENDIX D

HUD NOISE MEASUREMENT SYSTEM USE LOG

i

j Introduction

j The purpose of this Log is to help improve the KUD Noise Measurement System (NMS).

! Through the use of this Log, improvement can be made to both the written instructions and the hardware. The LOG should be returned to UBS each time the I!M3

is used. Please return it to:

D. S. Blomquist

National Bureau of Standards

Applied Acoustics Section

Sound Building, Rm. AIU9

Washington, D. C. 2023^

• • 301-921-3381

1 Office

\

ser

User's Telephone Number

Serial Number

Date Used

1. Was appropriate location for mounting system difficult to find? Briefly

describe any difficulty on the back of this sheet.

Yes No

2. Approximately how long did it take to find the mounting location.

3. Briefly describe any problems in obtaining permission to mount system,

(on the back of this sheet)

k. Where was system mounted?

utility standard

5. Approximate mounted height of system in feet

stake and pole other

6. Uho performed mounting? HUD Personnel

7- What was used for mounting?

_City or State Personnel

Ladder Other

Utility Company

Other

8. If you had any problems mounting system please describe them on back of

this sheet.

Yes No

9. Approximately how long did it take to mount the system.

51
10. Where was calibration performed? Office Measurement site.

If at measurement site, could Monitor indicator lights be seen?

Yes Yes, with difficulty ,

11. From the local newspaper obtain the maximum and minimum temperatures for the

measurement period.

Maximum temperature Minimum temperature

12. What were weather conditions? Rain Sleet Snow Clea

13. 1,1.0 performed demounting? Hud Personnel Utility Company

City or State Personnel Other

lU. If Dummy Monitor was mounted before Monitor was mounted, please answer

the following:

a. Period of time dummy was mounted (check):

Less than 2k hrs

2k Hrs

If more than 2k hrs, how long

b. Height above ground (ft)

c. . Was Monitor mounted at same height above ground as dummy?

Yes No, what was difference

d. Was there any visible damage to dummy. No

If yes, describe on back of sheet.

15- Were local police authorities notified? Yes No

16. Was there any evidence of vandalism? If yes, please describe nature of

damage and how you think this damage might have occurred (on back of this

sheet)

.

Yes No

IT. If system failed to calibrate the second time, or the data did not sum

between 23*95 and 2U.05 (MM printed out on Automatic Reader), please

complete the following questions.

a. Is there any water condensation in the Monitor case? Yes No

b. Were the Monitor batteries charged before use? Yes No

PROCEED NO FURTHER, GO TO QUESTION 21.

52
18.

Pleu.ce enter data here.

Time Level

Greater than 80 dB(A)

Greater than 75 dB(A)

Greater than 65 dB(A)

Greater than ^5 dB(A)

Performance of windscreen was exceeded

Number of events greater than 80 cLB(A)

If the time that the performance of windscreen was exceeded was greater

than 1 hour DO HOT PROCEED, GO TO QUESTION 21.

If the number of events greater than 80 dB(A) was more than 10, can you

identify the source, such as the site is: subject to aircraft operations

less than 3000 feet from railroad operations, near a manufacturing

operation, near a construction project, etc. (please describe on the back

of this sheet).

The following questions concern adjustments to the data. If no adjustments were

made for distance or future traffic flow do not answer questions 19 and 20.

19 . Was data corrected for different location? Yes Ho

If yes, (a) how much was the correction? dB

(b) was there more than one source identified? How many?

20. Was future noise exposure predicted from data? Yes No

If yes, please answer following:

a. What was correction for auto traffic? dB?

b. What was correction for truck traffic? dB?

c. What was combined correction? dB?

21. Explain any other difficulties; for example, more instructions are needed on mounting windsencor, banding material is difficult to use in cold weather,

shock cord is not necessary, adjustment of data for distance is difficult,

calculator is required for data calculations, etc.

53
ACKNOWLEDGEMENTS

The authors express their appreciation to the following members of the

Applied Acoustics Section: J. M. Heinen, C. 0. Shoemaker and J. S. Forrer

for trouble shooting and repair of the measurement system and M. Tarica and

T. M. Savoy for classification of the Use Logs.

The authors also recognize the significant contributions made by the

HUD Field Personnel.

54
NBS-114A (REV. 7-73)

U S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR RKPORT NO.

NBSIR 7-6-.1.16-9

2. Gov’t Accession

No.

4. TITLE AND SUBTITLE

f

tionale and Recommendations for Changes and Revisions to the

HUD Noise Measurement System Specifications

3. Recipient's Accession Ni

5. Publication Date

6. Performing Organization ( ode

7. AUTHOR(S)

Donald S. Blomquist, Marilyn A. Cadoff

8 . Performing Organ. Report No. NBSIR 76-1169

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2000453

11. Contract /Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Department of Housing and Urban Development

13. Type of Report & Period

Covered

Final Oct. 1977

14. Sponsoring Agency Code

15.

SUPPLEMENTARY NOTES

16.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.)

In 1973, the Office of Noise Abatement Research, Department of Housing and Urban

Development, contracted with the Applied Acoustics Section of the National Bureau

of Standards to develop a noise exposure measurement system. This system was subsequently developed, seventeen prototype units were procured, and a full-scale

laboratory and field evaluation of the units were conducted. This report discusses

the results of the evaluation, as well as the rationale behind and recommendations

for changes and revisions to the HUD noise measurement system specifications.

17.

KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Acoustics; community noise; environmental impact; noise; noise exposure measurement

system; sound.

18. AVAILABILITY Unlimited 19. SECURITY CLASS

(THIS REPORT)

[_ For Official Distribution. Do Not Release to NTIS

UNCL ASSIFIF.D Q Order From Sup. of Doc., U.S. Government Printing Office Washington. D.C. 20402. SD Cat. No. Cl 3

20. SECURITY CLASS

(THIS PAGE)

[1JC Order From National Technical Information Service (NT IS) Springfield, Virginia 22151 UNCLASSIFIED

21. NO. OF PAGES

57

22. Price

$ 5 - 2 ! USCOMM.DC 29C42-P"4
.

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