California Code of Regulations › Title 21 - Public Works › Division 2.5 - Division of Aeronautics (Department of Transportation) › Chapter 6 - Noise Standards › Article 1 - General › Section 5001 - Definitions

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
The definitions in the following subsections apply to this
					 subchapter.
(a) Air Carrier: Air
				  carrier is any aircraft operating pursuant to a federal certificate of public
				  convenience and necessity, including any certificate issued pursuant to
				  49 U.S.C. Section
				  1371 and any permit issued pursuant to
				  49 U.S.C. Section
				  1371.
(b) Aircraft Operator: Aircraft operator
				  means the legal or beneficial owner of the aircraft with authority to control
				  the aircraft utilization except where the aircraft is leased, the lessee is the
				  operator.
(c) Airport Proprietor:
				  Airport proprietor means the holder of an airport permit issued by the
				  department pursuant to Article 3, Chapter 4, Part 1, Division 9, Public
				  Utilities Code.
(d) Annual CNEL:
				  The annual CNEL, in decibels, is the average (on an energy basis) of the daily
				  CNEL over a 12-month period. The annual CNEL is calculated in accordance with
				  the following:
Annual CNEL = 10 log10 [(1/365)
					 [SIGMA] Antilog (CNEL(i)/10)]
where CNEL(i) = the daily CNEL for each day in a continuous
					 12-month period, and [SIGMA] means summation.
When the annual CNEL is approximated by measurements on a
					 statistical basis, as specified in Section
					 5034, the number 365 is replaced
					 by the number of days for which measurements are obtained.
(e) County: County, as used herein, shall
				  mean the county board of supervisors or its designee authorized to exercise the
				  powers and duties herein specified.
(f) Daily Community Noise Equivalent Level
				  (CNEL): Community noise equivalent level, in decibels, represents the average
				  daytime noise level during a 24-hour day, adjusted to an equivalent level to
				  account for the lower tolerance of people to noise during evening and night
				  time periods relative to the daytime period. Community noise equivalent level
				  is calculated from the hourly noise levels by the following:
CNEL = 10 log (1/24) [[SIGMA] antilog (HNLD/10) + 3
					 [SIGMA] antilog (HNLE/10) + 10 [SIGMA] antilog (HNLN/10)]
Where
HNLD are the hourly noise levels for the period 0700-1900
					 hours;
HNLE are the hourly noise levels for the period 1900-2200
					 hours;
HNLN are the hourly noise levels for the period 2200-0700
					 hours; and [SIGMA] means summation.
(g) Department: Department means the
				  Department of Transportation of the State of California.
(h) General Aviation: General aviation
				  aircraft are all aircraft other than air carrier aircraft and military
				  aircraft.
(i) Hourly Noise Level
				  (HNL): The hourly noise level, in decibels, is the average (on an energy basis)
				  noise level during a particular hour. Hourly noise level is determined by
				  subtracting 35.6 decibels (equal to 10 log10 3600) from
				  the noise exposure level measured during the particular hour, integrating for
				  those periods during which the noise level exceeds a threshold noise level.
For implementation in this subchapter of these regulations,
					 the threshold noise level shall be a noise level which is 10 decibels below the
					 numerical value of the appropriate Community Noise Equivalent Level (CNEL)
					 standard specified in Section
					 5012. At some microphone
					 locations, sources of noise other than aircraft may contribute to the CNEL.
					 Where the airport proprietor can demonstrate that the accuracy of the CNEL
					 measurement will remain within the required tolerance specified in Section
					 5070, the department may grant a
					 waiver to increase the threshold noise level.
(j) Noise Exposure Level (NEL): The noise
				  exposure level is the level of noise accumulated during a given event, with
				  reference to a duration of one second. More specifically, noise exposure level,
				  in decibels, is the level of the time-integrated A-weighted squared sound
				  pressure for a stated time interval or event, based on the reference pressure
				  of 20 micronewtons per square meter and reference duration of one
				  second.
(k) Noise Impact Area:
				  Noise impact area is the area within the noise impact boundary that is composed
				  of incompatible land use.
(l) Noise
				  Impact Boundary: Noise impact boundary is the locus of points around an airport
				  for which the annual CNEL is equal to the airport noise standard established in
				  Section 5012. The concepts of noise impact
				  boundary and noise impact area are illustrated in Figure 1.
Click
					 here to view image
(m) Noise Level (NL): Noise level is the
				  measure in decibels of an A-weighted sound pressure level as measured using the
				  slow dynamic characteristic for sound level meters specified in American
				  National Standard Specification for Sound Level Meters, (ANSI S
				  1.4-1983 as revised by ANSI S
				  1.4 A-1985) which is hereby
				  incorporated by reference. The A-weighting characteristic modifies the
				  frequency response of the measuring instrument to account approximately for the
				  frequency characteristics of the human ear. The reference pressure is 20
				  micronewtons/square meter (2 x 10-4
				  microbar).
(n) Noise Problem
				  Airport: "Noise problem airport" is an airport that the county in which the
				  airport is located has declared to have a noise problem under section
				  5020.
(o) Single Event Noise Exposure Level
				  (SENEL): The single event noise exposure level, in decibels, is the noise
				  exposure level of a single event, such as an aircraft flyby, measured over the
				  time interval between the initial and final times for which the noise level of
				  a single event exceeds a predetermined threshold noise level.
(p) Sound Pressure Level (SPL): The sound
				  pressure level, in decibels (dB), of a sound is 20 times the logarithm to the
				  base 10 of the ratio of the pressure of that sound to the reference pressure 20
				  micronewtons/square meter (2 x 10-4
				  microbar).
1.
					 Renumbering and amendment of former Section
					 5001 to Section
					 5002, and renumbering and
					 amendment of former Section
					 5006 to Section
					 5001 filed 2-20-90; operative
					 3-22-90 (Register 90, No. 10). For prior history, see Register 79, No.
					 21.
Note: Authority cited: Section
						21669,
						Public Utilities Code. Reference: Sections
						21669-
						21669.4,
						Public Utilities Code.