NBSIR 73-192

Acoustical Evaluation of a Single

Family Detached Honeycomb Panel

Housing System Constructed on an

Operation Breakthrough Prototype Site

Thomas L. Quindry

Applied Acoustics and Illumination Section

Center for Building Technology (Building Research Division)

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

April 1973

Final Report

Prepared for Office of Research and Technology

Department of Housing and Urban Development

Washington, D. C. 20410

NBSIR 73-192

ACOUSTICAL EVALUATION OF A SINGLE

FAMILY DETACHED HONEYCOMB PANEL

HOUSING SYSTEM CONSTRUCTED ON AN

OPERATION BREAKTHROUGH PROTOTYPE SITE

Thomas L. Quindry

Applied Acoustics and Illumination Section Center for Building Technology (Building Research Division)

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

April 1973

Final Report

Prepared for Office of Research and Technology

Department of Housing and Urban Development

Washington, D. C. 20410

U. S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

IMATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

ACOUSTICAL EVALUATION OF A SINGLE FAMILY DETACHED

HONEYCOMB PANEL HOUSING SYSTEM CONSTRUCTED

ON AN OPERATION BREAKTHROUGH PROTOTYPE SITE

by

Thomas L. Quindry

Applied Acoustics and Illumination Section

Building Research Division

ABSTRACT

The acoustical performance of a single family detached honeycomb

panel housing system was tested on an Operation BREAKTHROUGH prototype

site.

Test results are given concerning the noise isolation of Intradwelllng walls and the noise levels within living units.

Key Words: Acoustics; noise criterion curve; noise isolation class;

Operation BREAKTHROUGH

1
TABLE OF CONTENTS

PAGE

Abstract i

1. Introduction 1

2. Objective 1

3. Test Procedure 2

4. Description of Housing System 4

5. Test Results 5

5.1 Noise Isolation of Intra-Dwelling Walls 5

5.2 Noise Level Within Living Unit 6

6. Field Tests on a Similar System 6

7. Discussion 7

Table 1 g

Table 2 ^ ^ g

Table 3 m

ii
1 . INTRODUCTION

Drawings and specifications for the housing systems being demonstrated as a part of Operation BREAKTHROUGH were reviewed in order to

determine the acoustical performance of the dwelling units. Any potential

deficiencies in acoustic performance were noted such that appropriate

action could be taken prior to manufacture and site installation of the

housing units.

Poor workmanship, however, can negate even the best planned

acoustical improvement. The many unknowns associated with workmanship,

possible damage to the housing modules during shipment, assembly of the

housing modules on the building site, and even the modular concept of

construction typical of many of the Operation BREAKTHROUGH housing

systems, emphasized the importance of performance testing.

More builders than ever before are now at least aware that acoustic

quality in buildings is becoming an essential consumer requirement. A

great deal of information can ultimately be drawn from the acoustical

performance testing of Operation BREAKTHROUGH housing.

2 . OBJECTIVE

The objective of this work was to obtain information regarding

interior noise levels and the intra-dwelling noise isolation provided

by this prototype housing system constructed within the Operation

BREAKTHROUGH Program on one of the prototype sites, and to provide this

information as a data base for possible comparison with the acoustical

performance of conventional housing.

1
3. TEST PROCEDURE

All tests were performed in accordance with the methods outlined

in the appropriate standards. The pertinent tests include:

Appendix Al of ASTM E 336-71, "Recommended Practice for the

Measurement of Airborne Sound Insulation in Buildings."

ASTM E413-70T, "Tentative Classification for Determination

of Sound Transmission Class." (This test method is used

for the determination of Noise Isolation Class.)

ASTM C 423-66, "Standard Method of Test for Sound Absorption of Acoustical Materials in Reverberation Rooms,"

Section 9.1, for measurement of decay rate procedure.

ANSI SI. 2-1962, "ANSI Standard Method for the Physical

Measurement of Sound."

All measurements were carried out using the NBS Mobile Acoustical

Laboratory ^''^^ A complete list of the equipment utilized for these

measurements is given in Table 1.

Airborne noise reduction was measured using 1/3-octave bands

(2) of pink random noise to excite the speaker systems. A multiplex

system which scanned the outputs of the microphones was used for

simultaneous spatial averaging in both the source and receiving rooms.

The output of the multiplexer was passed through a 1/3-octave band-pass

filter set and then to the measuring system.

(1) Winzer, George E. , National Bureau of Standards Mobile Acoustical

Laboratory, Sound and Vibration, May 1970.

(2) Pink random noise is a quantity (e.g. , sound pressure) whose

amplitude probability is a normal (Gaussian) distribution curve and whose frequency spectrum slopes at minus 3 dB per octave.

2
A total of five microphones, in a modified spherical array as

shown in Figure 1, was used in all rooms. The distribution of sound

in the source room was improved by the addition of an 8 ft x 11 ft

honeycomb reflecting panel placed at an angle such that its top edge

was resting across the entire wall that was opposite the primary test

wall.

Temporal averages of sound pressure levels were obtained using a

true root-mean-square voltmeter in order to obtain less statistical

error in sound pressure levels than can be obtained with the graphic

level recorder recommended in ASTM E 336-71. A differential amplifier

was used with two true r.m.s. voltmeters to obtain the differences in the

r.m.s. sound pressure levels of tke random noise between the source and

the receiving room. Airborne noise reduction determination averaging

time of 100 seconds for tests at frequencies from 125 through 400 Hz

and 30 seconds for tests at frequencies from 500 through 4000 Hz were

used in order to achieve a statistical error (due to temporal averaging)

of less than + 0.4 dB (at a confidence level of 95 percent).

The uncertainty in measured sound pressure levels, due to random

and systematic uncertainties associated with the overall data acquistition

system, is estimated (95 percent confidence level) to be less than + 1 dB

for relative sound pressure levels (measured to determine airborne noise

reductions) over a range of band-center frequencies from 100 to 4000 Hz.

ASTM E 336-71 specifies that for suitable accuracy in determining the

average sound pressure levels in the source and receiving rooms , the

3
rooms shall be large enough that there are at least 10 normal modes

per measurement bandwidth. The lower limit of frequency for which this

would occur using 1/3 octave bands was: 200 Hz for the bathroom, 155 Hz

for the bedroom and 112 Hz for the living rooms.

For the airborne noise reduction measurements the background

noise in the receiving room was at least 10 dB below the transmitted

signal. The equivalent sound absorption of the receiving rooms was

determined by the reverberation decay method described in ASTM C 423-66.

Measurements of noise levels of certain mechanical equipment were

(3) carried out for comparison with the Noise Criterion (NC) contours

An octave band-pass filter set and graphic level recorder were used for

these measurements. The background noise in the receiving room was at

least 10 dB below the sound pressure level of the equipment being

measured .

>

During the field measurements the temperature was nominally 65°

and the relative humidity 50%.

4. DESCRIPTION OF HOUSING SYSTEM

The housing system which was tested is classified as a single family

detached housing system. It was a panelized system consisting of a

three bedroom/bath module, a living room/kitchen module, and a family

room/bedroom/bath module. The three modules were joined by interconnecting hallways to form a single story dwelling. The floor plan of the

three bedroom/bath module which was tested is shown in Figure 1. The

(3) Schultz, T. J., Noise Criterion Curves for use with the USASI

Preferred Frequencies," J. Acoust. Soc. Am. 43^, 637-638 (1968).
living units were unfurnished except for kitchen equipment. The living

room, hallways and bedrooms were carpeted. The kitchen and bathroom

floor areas were covered with vinyl asbestos tile.

The modules were erected over a shallow crawl space and were

supported by a steel grade beam at the perimeter which housed the supply

and return ducts as well as electrical raceways. The interior wall is

composed of 4 '4" x 8' 3 1/4" panels, nominally 2 inches thick, with paper

honeycomb cores and primed galvanized sheet steel faces. The exterior

wall is similar to the interior wall except the honeycomb panels are

nominally 3 inches thick with foamed polyurethane insulation projecting

into the honeycomb core approximately 1 1/2 inches on the exterior side.

The exterior wall panels are joined on the vertical sides by wood tongue

and groove joints.

The floor system is 3-3/8 inch honeycomb with 3/8-inch plywood

face on the top surface and a galvanized sheet steel face on the bottom

surface. The roof is of a construction similar to the exterior walls

except that the polyurethane insulation projects into the honeycomb core

2 1/4 inches. Cross-sections of the wall, ceiling, and floor constructions are shown in Figure 2.

5. TEST RESULTS

5.1 Noise Isolation of Intra-Dwelling Walls

Each measured noise reduction was normalized to a reference

2 2 receiving room absorption, , of 10 m (100 ft ) according to the

following equation:

5
NR^^ = NR - (10 loR^^j ^ )

<> wli< ii> NK " Noriii.il l/.c(l muIhi* iftliicl ion

n NR = Noise reduction before normalization

A = Total sound absorption of the receiving space.

The results of measurements of the normalized noise reduction

between horizontally adjacent bedrooms and bedroom to bathroom are

shown as a function of frequency in Figures 3 and 4. The three-segmented

solid line represents the Noise Isolation Class (NIC) contour fitted to

these data according to the specified ASTM procedure. The arrow points

to the normalized NIC value. The normalized NIC values are given in

Table 2.

5.2 Noise Level Within Living Unit

The noise level in bedroom #1 with the heating system in operation

is given in Figure 5 along with the Noise Criterion (NC) contours. The

measured NC value is given in Table 2.

6. FIELD TESTS ON A SIMILAR SYSTEM

An engineering model was constructed according to the Operation

BREAKTHROUGH systan drawings inside an assembly plant prior to the erection

of the Operation BREAKTHROUGH units. This unit was tested before the

availability of the Operation BREAKTHROUGH units in order to obtain

information regarding the system. These tests provided much insight

into the intra-dwelling noise isolation provided by a metal panel,

honeycomb core construction system, particularly since the floor plan

layout was such that buffer zones were created between rooms either by

closets or hallways. A comparison of data is given in Table 3. An

6
estimate of the effectiveness of the exterior shell of the engineering

model in attenuating exterior noise was measured. Since the engineering

model was located in a factory the recommended procedures for measurement

of the exterior shell attenuation could not be followed. The results,

however, did give some indication of the expected performance of the

exterior shell.

For the purposes of estimating the Noise Criterion contour which

one might expect in an urban area, available noise data for an Operation

BREAKTHROUGH prototype sit6 were compared with the noise reduction

obtained with the engineering model. It was estimated that from exterior

noise sources the noise level would be from NC 50 to NC 65.

As a result of these findings, the joining configuration of the

exterior panels , which had been pinpointed as the cause for poor performance, was re-designed by the producer. Inspection of the

prototype units on the BREAKTHROUGH site indicated that the exterior

shell attenuation was improved. Weather conditions prohibited a field

test of the exterior shell.

7. DISCUSSION

The acoustical performance of this housing system was improved by

careful design and evaluation of the system in conjunction with the

acoustical criteria of Operation BREAKTHROUGH. Major changes which

improved the acoustical performance of the dwelling unit included

modification of the exterior shell and inclusion of a quieter heating

unit.

7
Table 1

Instrumentation*

1. Briiel & Kj aer 1402 Random Noise Generator

2. (3) Bruel & Kjaer Models 1612, 5004 Band-Pass Filter Sets

3. JBL Speaker Systems

4. (2) Bruel & Kjaer 2606 Measuring Amplifier

5. (2) Bruel & Kjaer 215 RMS Converter & Log Amplifier

6. (2) Bruel & Kjaer 221 Microphone Energizer - Multiplixer

7. Bruel & Kjaer 2305 Graphic Level Recorder

8. (12) Briiel & Kjaer 4132 Condensor Microphones

9. (12) Bruel & Kjaer 2619 FET Preamplifier

: (2) Briiel & Kjaer 4220 Pistonphone

.11. ..; NBS Differential Amplifier

12. NBS Reverberation Time Measuring System

13. HP 5325 A Counter

^Commerical instruments are identified in this report in order to

adequately specify the experimental procedure. In no case does

such identification imply recommendation or endorsement by the

National Bureau of Standards, nor does it imply that the equipment

identified is necessarily the best available for the purpose.

8
Table 2

Tlie Measured Nol.se Isolation Characteristics

of the lloiiHliig System

Source Room Receive Room Normalized

Partition Unit Unit NIC

Intra-dwelling Bathroom Master Bedroom 33

Wall 16-SFD/03-02 16-SFD/03-02

Intra-dwelling Back Bedroom Middle Bedroom 29

Wall 16/SFD/03-02 16-SFD/03-02

Table 2 (cont.)

Receive Room

Equipment Unit NC

Heater on

1

!

; Master Bedroom <40

1 16-SFD/03-02

9
Table 3

The Measured Noise Characteristics of the BREAKTHROUGH Housing System

Compared with the Measured Noise Characteristics of the

Engineering Model

!

t Normalized NIC

i Partition

Source Room

Unit

Receive Room

Unit

BREAKTHROUGH

Engineering

Model

j Intra-dwelling ,

i Wall

i

Bathroom Master

Bedroom

33 33

i

i Intra-dwelling

j Wall

i

Back

Bedroom

1 Middle

Bedroom

\

29 30

Table 3 (cont.)

NC

Equipment

Receive Room

Unit BREAKTHROUGH

Engineering

Model

Heater on

1

Master

bedroom ^40 <55

10
REFLECTOR PANEL

I JL.\ =^

MICROPHONE POSITIONS-

(typ)

\—

ENTRY

1—

X X

BEDROOM 3

X

WARDROBE WARDROBE

^X

X

BEDROOM 2

X X

#INTRA-DWELLING WAUj

SPEAKER POSITIONS

(typ)

-^EXTERIOR WALL

Figure i„ Floor plan showing microphone and speaker positions.

11
POLYURETHANE

INSULATION

CEILING CHANNEL

WALL SUPPORT 37^'!'

PAPER HONEYCOMB CORE

^26 GAUGE (.0179") GALVANIZED STEEL —^^-M ^ FACES

^ / T

3"

1/2'

CEILING PANEL

INTERIOR WALL PANEL

26 GAUGE (.0179") GALVANIZED STEEL FACES

* 2"

FLOOR CHANNEL

WALL SUPPORT

PAPER HONEYCOMB CORE

1- FLOOR PANEL

CARPET a PAD

"Tl/2"

PAPER HONEYCOMB CORE

POLYURETHANE

INSULATION ^

jjJigpSO i~ 3/8" PLYWOOD FACE

r

i

1 _

* H/2" ,

2 6 GAUGE (.0179") GALVANIZED STEEL

FACES

EXTERIOR WALL PANEL

Figure 2. Cross sections of wall, ceiling, and floor constructions.

12
Figure 3. Normalized 1/3-Octave Band Noise Reduction Between the

Bathroom and Bedroom No. 1 Separated by an Intra-Dwelling

Wall. Unit 16-SFD/03-02 (NIC - 33).

13
1 t ! 1 I t 1 I I I I 1 I I t I 125 250 500 IK 2K 4K

FREQUENCY, Hz

(NORMALIZED TO Ao = 10 METRIC SABINS)

Figure 4. Normalized 1/3-Octave Band Noise Reduction Between

Bedroom No. 2 and Bedroom No. 3 Separated by an IntraDwelling Wall. Unit 16-SFD/03-02 (NIC - 29).

14
J I I I

I I I I 63 125 250 500 IK 2K 4K 8K

FREQUENCY, Hz

Figure 5. Octave Band Sound Pressure Level in Bedroom No. 1.

Unit 15-SFD/03-02 With the Heating System Running.

(< NC - 40)

15

FORM NBS-IHA (1.711 U.S. DEPT. OF COMM. 1. ITBl-K A I K.n; 0.< Ki;[->OkT no. 2. Gov't Accession

BIBLIOGRAPHIC DATA ^,3^^^ ,3_^g2

4 TITI F 'WD sliRTITI F Acoustical Evaluation of a Single Family Detached Honeycomb

Panel Housing System Constructed on an Operation BREAKTHROUGH

Prototype Site

5* Pub 1 1 ca tton Da te

6. Performing Organization Code

7. AL'THOR(S)

Thomas L. Quindry

8, Performing Organization

NBSIR 73-19?

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/ Task, *ork IJnit No. 4600450

11. Contract/Grant No.

T A A U If, 7n

12. Sponsoring Organization Name and Address

Office of Research and Technology

Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report & Period C ove re dFinal

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.)

The acoustical performance of a single family detached honeycomb panel

housing system was tested on an Operation BREAKTHROUGH prototype site.

Test results are given concerning the noise isolation of intradwelling walls and

the noise levels within living units.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Acoustics; noise criterion curve.s; noise isolation class; Operation BREAKTHROUGH

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