[Equation 1]
TITLE 35: ENVIRONMENTAL PROTECTION
SUBTITLE H: NOISE
CHAPTER I: ILLINOIS POLLUTION CONTROL BOARD
PART 910
MEASUREMENT PROCEDURES FOR THE ENFORCEMENT
OF 35 ILL. ADM. CODE 900 & 901
Section
| 910.100 | General |
| 910.102 | Instrumentation |
| 910.103 | Definitions |
| 910.104 | Measurement Techniques for 35 Ill. Adm. Code 900 |
| 910.105 | Measurement Techniques for 35 Ill. Adm. Code 901 |
| 910.106 | Protocols for Determination of Sound Levels | |
| 910.107 | Measurement Techniques for Highly-Impulsive Sound Under 35 Ill. Adm. Code 104 | |
| 910.APPENDIX A | |
| Tables of Long-Term Background Ambient Noise |
| 910. TABLE A | Daytime long-term background ambient Leq levels in decibels by land use categories and 1/3 octave-band level |
| 910. TABLE B | Nighttime long-term background ambient Leq levels in decibels by land use categories and 1/3- octave-band level |
| 910. TABLE C | Daytime long-term background ambient Leq levels in decibels by land use categories and octave-band level |
| 910. TABLE D | Nighttime long-term background ambient Leq levels in decibels by land use categories and octave-band level |
AUTHORITY: Implementing and authorized by Sections 25 and 27 of the Environmental Protection Act [415 ILCS 5/25 and 27]
SOURCE: Adopted in R03-9 at 30 Ill. Reg. 5594, effective March 10, 2006.
| Section 910.100 | General |
This Part specifies the instrumentation to be used when conducting acoustical noise measurements and sets forth the specific acoustical measurement techniques to be employed when conducting time-averaged sound level (Leq) measurements. The instrumentation requirements and measurement techniques as more specifically set forth in this Part must be used in determining whether a noise source is in compliance with 35 Ill. Adm. Code 900 and 901.
Section 910.102 Instrumentation
a) Sound Measuring Equipment
| 1) | An integrating sound level meter used alone or used in conjunction with an octave-band or 1/3 octave-band filter set or a real-time sound analyzer (octave-band or 1/3 octave-band) must conform with the following standards incorporated by reference at 35 Ill. Adm. Code 900.106: |
| A) | ANSI S1.4 – 1983 (R2001) “American National Standard Specification for Sound Level Meters”, and ANSI S1.4 A-1985 “Amendment to ANSI S1.4-1983.” |
| B) | ANSI S1.11 - 1986 (R1998) “American National Standard Specifications for Octave-Band and Fractional-Octave-Band Analog and Digital Filters.” |
| C) | ANSI S1.6 – 1984 (R2001) “American National Standard Preferred Frequencies, Frequency Levels, and Band Numbers for Acoustical Measurements.” |
| D) | ANSI S1.8 - 1989 “American National Standard Reference Quantities for Acoustical Levels.” |
| E) | International Electrotechnical Commission, IEC 804-2000 Integrating/Averaging Sound Level Meters. | ||
| 2) | A magnetic tape recorder, graphic level recorder or other indicating device used must meet the requirements of the Society of Automotive Engineers (SAE) Recommended Practice J184 “Qualifying a Sound Data Acquisition System,” November 1998, incorporated by reference at 35 Ill. Adm. Code 900.106 | ||
| 3) | The laboratory calibration of instrumentation used for acoustic measurement must be traceable to the National Bureau of Standards, and must be performed no less often than once every 12 months. | ||
| 4) | For outdoor measurement, a windscreen must be attached to the microphone. | ||
b) Weather Measuring Equipment
| 1) | An anemometer and compass or other devices must be used to measure wind speed and direction in accordance with the manufacturer's recommended procedures. |
| 2) | A thermometer, designed to measure ambient temperature, must be used in accordance with the manufacturer's recommended procedures. |
| 3) | A hygrometer must be used in accordance with the manufacturer's recommended procedures to measure the relative humidity. |
| 4) | A barometer must be used in accordance with the manufacturer's recommended procedures to measure the barometric pressure. |
| Section 910.103 | Definitions |
| The definitions contained in 35 Ill. Adm. Code 900.101 apply to this Part. | |
| Section 910.104 | Measurement Techniques for 35 Ill. Adm. Code 900 |
Sound pressure level measurements are not required to establish a violation of 35 Ill. Adm. Code 900.102 (nuisance noise). However, sound pressure level measurements may be introduced as corroborating evidence when alleging a violation of 35 Ill. Adm. Code 900.102. If sound pressure level measurements are collected, manufacturer’s instructions must be followed for the equipment used and 35 Ill. Adm. Code 910.105 may be used as guidance in gathering data.
| Section 910.105 | Measurement Techniques for 35 Ill. Adm. Code 901 |
Sound pressure level measurements must be obtained in accordance with the following measurement techniques to determine whether a noise source is in compliance with 35 Ill. Adm. Code 901:
| a) | Site Selection |
| 1) | Measurements may be taken at one or more microphone positions within the appropriate receiving land. Measurement instruments must be set up outdoors within the boundaries of the receiving land for the purpose of determining whether a noise source is in compliance with 35 Ill. Adm. Code 901. |
| 2) | Measurement instruments must be set up not less than 25 feet (7.6 meters (m)) from the property-line-noise-source. The 25-foot (7.6 m) setback requirement is from the noise source and not the property line unless the noise source is contiguous to the property line. |
| 3) | Other measurement locations may be used for investigatory purposes such as, but not limited to, the following: |
| A) | Determining the extent of noise pollution caused by the source of sound; |
| B) | Determining the ambient; and |
| C) | Analyzing those acoustical parameters that describe the sound source. |
| 4) | For measurements of sound sources with no audible discrete tones, microphones should not be set up less than 25 feet (7.6 m) from any reflective surface that may affect data. If measurements must be taken within 25 feet (7.6 m), the effect, if any, of the reflective surface on the measured data must be determined. |
| 5) | For measurements of sound sources with audible discrete tones, microphones must not be set up less than 50 feet (15.2 m) from any reflective surface that may affect data. If measurements must be taken within 50 feet (15.2 m), the effect, if any, of the reflective surface on the measured data must be determined. |
| 6) | Objects with small dimensions (trees, posts, bushes, etc.) must not be within 5 feet (1.5 m) of the microphone position. If measurements must be taken within 5 feet (1.5 m) of such objects, the effect, if any, on the measured data must be determined. |
| b) | Instrumentation Set Up |
| 1) | A tripod must be set at the chosen site. The tripod must be extended to a height between 3 feet 8 inches (1.12 m) and 4 feet 10 inches (1.47 m) above ground. |
| 2) | A microphone must be attached to the appropriate end of a 5-foot (1.5 m) or longer cable and must be affixed to the top of the tripod. The other end of the cable must be connected to the measuring instrument. |
| 3) | The angle of incidence of the microphone must be adjusted to yield the flattest frequency response in accordance with the manufacturer’s specifications. |
| 4) | The measuring instrument must be separated from the microphone so as to minimize any influence on the measurements. The cable movement must be minimized during the measurement period. |
| c) | Measurement Site Operation and Instrument Calibration |
| 1) | Before taking sound pressure level measurements, measure and record (near the measurement site): |
| A) | Wind speed and direction; |
| B) | Ambient temperature; |
| C) | Relative humidity; and |
| D) | Barometric pressure. |
| 2) | Turn the measuring instrument on and allow the instrument to stabilize. Monitor and record the battery condition of the calibrator and all measuring instruments. |
| 3) | Turn the calibrator on at its appropriate frequency. Allow the calibrator to stabilize and calibrate the measuring system according to the manufacturer's specifications. After the measuring system has been calibrated, remove the calibrator and attach a windscreen to the microphone. |
| 4) | Adjust the microphone to the angle of incidence that will yield the frequency response in accordance with the manufacturer's specifications. |
| 5) | Measure the sound pressure level data within the limitations of subsection (d) and according to the manufacturer's recommended procedures. Other sound pressure levels may be used for investigatory purposes such as, but not limited to, the following: |
| A) | Determining the extent of noise pollution caused by the source of sound; |
| B) | Determining the ambient; and |
| C) | Analyzing those acoustical parameters that describe the sound source. |
| 6) | While sound measurements are being taken, the operator must be separated from the microphone so as to minimize any influence on the measurements. |
| 7) | While measurements are being taken, visual and aural surveillance of extraneous sound sources and varying wind conditions must be made to insure that the conditions of measurement are accurately known. Record any variations in these parameters that may affect data. The number and basis for affected data block must be recorded. When using a tape recorder, voice commentary concerning conditions will be recorded on the cue track. |
| 8) | To minimize wind effects on the microphone, sound measurements must not be taken when the wind velocity is greater than 12 miles per hour (5.4 m/second) at the microphone position. |
| 9) | For the purposes of data correction, the ambient sound at the measurement site must be determined by means of measurement or analysis. |
| 10) | After taking sound pressure level measurements, remove the windscreen and attach the calibrator to the microphone. Turn the calibrator on at its appropriate frequency. After allowing the calibrator to stabilize, monitor and record the measuring system response. When the measuring system response varies by more than + 0.5 dB from the most recent field calibration, the sound pressure level measurements obtained since such most recent field calibration cannot be used for enforcement purposes. |
| 11) | Before removing the calibrator from the microphone, turn the calibrator off. If the ambient sound has not been determined by means of measurement, determine the noise floor of the measuring system. If the noise floor is within 10 dB of the measured sound pressure level data, such noise floor measurements must be recorded. |
| 12) | At the end of the sound survey, monitor and record the battery condition of the calibrator and all measuring instruments. Near the measurement site, measure and record: |
| A) | Windspeed and direction; |
| B) | Ambient temperature; |
| C) | Relative humidity; and |
| D) | Barometric pressure. |
| 13) | Record the physical and topographical description of the ground surface within the vicinity of the measurement site, survey site location, a description of the sound source, a diagram of the area, the location of reflective surfaces near the microphone, and the approximate location of the noise source relative to the microphone position. |
| 14) | A magnetic tape recorder may be used to preserve the raw data. Calibration signals must be recorded at the beginning and end of each tape as well as at intermediate times such as when relocating to a new measurement site. Voice commentary concerning local conditions and affected data blocks must be recorded on the cue track. The original tape recording must be preserved for subsequent evaluation. Laboratory analyses may be performed on magnetic tape recorded field data. A description of the laboratory instrumentation and procedures must be recorded. Analyses used in the laboratory must be correlated to field measurement techniques. |
| d) | Limiting Procedures for Specific Types of Data Acquisition |
| 1) | For measurements of non-impulsive sound with audible discrete tones, 1/3 octave-band sound pressure levels must be obtained in determining whether a noise source is in compliance with 35 Ill. Adm. Code 901.106. |
| 2) | For measurements of non-impulsive sound with no audible discrete tones, octave-band sound pressure levels must be obtained in determining whether a noise source is in compliance with 35 Ill. Adm. Code 901.102 and 901.103. |
| e) | Correction Factors |
If necessary, correction factors rounded to the nearest 1/2 decibel must be applied to sound pressure level measurements. The correction factors applicable to the measurement system may include, but are not limited to, corrections for windscreen interference and the sound pressure level difference between consecutive field calibrations. Such calibration correction factors must only be used to make negative corrections (subtraction from the field data). In no case must such calibration correction factors be added to the measured sound pressure levels so as to raise the sound pressure level field data. The correction factors applicable to the measurement site may include, but are not limited to, corrections for reflective surfaces and ambient sound.
Section 910.106 Protocols for Determination of Sound Levels
| a) | The raw data collection procedures for the determination of equivalent continuous sound pressure level (Leq) are described in this Section using as an example the determination of a 1-hour Leq corrected for ambient. The following procedures must be used: |
1) Using small blocks:
| A) | The 1-hour interval is divided into many small blocks of time so that corruption of the data from short-term background transient sound and loss of data can be limited to the corrupted or bad blocks. The block duration in seconds must remain fixed for any measurement hour. The duration must be neither less than 10 seconds nor greater than 100 seconds. For example, if the block duration is chosen to be 60 seconds (1 minute), then the data collection proceeds for 60, 1-minute periods of measurement. |
| B) | The collected data for each block represents a block duration Leq (or sound exposure level (SEL)) in octave-bands (or 1/3 octave-bands if prominent discrete tones may be present). |
| C) | Data for any block corrupted by one or more short-term background transient sounds must be deleted. |
| D) | After deleting corrupted data blocks, there will be a fixed number of “good” data blocks remaining. This number is designated as NPLNS, where PLNS stands for Property-Line-Noise-Source. These remaining “good” blocks must be numbered consecutively. The subscript i is used to denote the numbering of the blocks in time order after corrupted data blocks have been deleted. |
| E) | The data for the NPLNS remaining blocks are time averaged on an energy basis by octave (or 1/3 octave-band) using Equation 1 below. In this equation, two subscripts are used, i to designate time and j to designate the specific frequency, either an octave-band or 1/3 octave-band. The raw, 1-hour Leq in the jth frequency band is given by: | ||
[Equation 1]
where Leq is the Leq in the jth frequency band for the ith non-deleted data block.
| F) | In terms of SEL, the raw SEL in the jth frequency band is given by: |
[Equation 2]
| G) | The raw, 1-hour Leq in the jth frequency band is given in terms of the corresponding SELj by: |
[Equation 3]
Where T is the block duration in seconds, NPLNS is the number of non-discarded data blocks, and 3600 is the number of seconds in an hour.
2) Continuous Data Collection:
| A) | The measuring instrument must be adjusted to continuously measure sound pressure and accumulate Leq for each block of time. For convenience, the hour may be split into several smaller blocks such as 10, 6-minute blocks or 4, 15-minute blocks, etc. |
| B) | A switch on the measuring instrument must be available to inhibit data collection whenever a short-term background transient sound occurs. This switch shall be used to prevent short-term background ambient sounds from corrupting the data. |
| C) | Data collection must proceed for one hour. The energy average of the several measured Leqij each weighted by the number of seconds actually accumulated during the ith block results in the raw, 1-hour Leq in each frequency band given by: |
[Equation 4]
Where Leqij is the Leq in the jth frequency band for the ith large block. Ti is the actual number of seconds of “good” data accumulated in the ith block of time (e.g., 6 to 15 minutes); and
[Equation 5]
| 3) | Minimum data collection requirements: |
| A) | Initial Measurement Duration. The property-line-noise-source measurements must proceed initially for one hour. Because of correction for short-term background transient sounds, actual reported data collection time T, in seconds, may be less than 3600 seconds (one hour). |
| i) | If small blocks of data are used for data collection, then the total measurement duration in seconds, TPLNS, is given by NPLNS T, where T is the length of each block in seconds and NPLNS is the number of non-discarded blocks. If data inhibition is used for data collection, then TPLNS is the number of non-inhibited seconds during the measurement hour. In either case, TPLNS must be no less than 900 seconds. |
| ii) | If very few blocks were used for data collection, then the duration of each block, T, may be too long and should be reduced. |
| iii) | For either data collection method, sounds considered to be short-term transient may actually be part of the long-term background ambient and should be so redefined. |
| B) | Extended Measurement Duration. If TPLNS is less than 900 seconds during the first hour of measurements, the raw data collection procedures must be appropriately modified and new measurements must proceed for an additional hour. If TPLNS after combining the first and the second hour of measurements is also less than 900 seconds, then the raw data collection must continue using the data inhibition method or method employed during the second hour until TPLNS is greater than or equal to 900 seconds. |
| 4) | Correction for Long-Term Background Ambient Sound: |
| A) | The raw 1-hour Leq must be corrected for long-term background ambient sound. Subsection (b) of this Section describes methods to obtain the long-term background ambient sound level in the jth frequency band. The correction is dependent on the difference (in decibels) between the raw, 1-hour, jth band property-line-noise-source: Leqj and corresponding jth band long-term background ambient sound level. The correction to be applied is as follows: |
| i) | If the difference between the raw 1-hour Leq and the long-term background ambient sound is larger than 10 decibels, then the correction must be set to 0. |
| ii) | If the difference between the raw 1-hour Leq and the long-term background ambient sound difference is less than 3 decibels, then the jth frequency-band level, Leqj, must be set equal to 0. |
| iii) | If the difference between the raw 1-hour Leq and the long-term background ambient sound is between 3 and 10 decibels, then the correction given in Table 1 below must be subtracted from the raw, 1-hour property-line-noise-source Leqj |
Table 1
Corrections in dB for long-term
background ambient sound
Difference |
Correction |
|
(dB) |
(dB) |
|
3 |
3 |
|
4 |
2.3 |
|
5 |
1.7 |
|
6 |
1.3 |
|
7 |
1.0 |
|
8 |
0.7 |
|
9 |
0.6 |
|
10 |
0.5 |
| B) | The long-term background ambient corrected level must be the property-line-noise-source Leqj reported for the jth frequency band. |
b) Obtaining the background ambient sound level:
| 1) | The background ambient must be measured for the purposes of this Section during a 10-minute interval. |
| 2) | Long-term background ambient measurement procedures are similar to procedures to measure the property-line-noise-source itself. Eliminating short-term background ambient transient sounds from the measurement of average long-term background ambient sound proceeds in a manner similar to the measurement of the property-line-noise-source emissions themselves. The two methods for measurement are: to divide the 10-minute measurement into short blocks of data, or inhibit data collection when short-term background transient sounds occur. The same method must be used for gathering both the property-line-noise-source data and the corresponding long-term background ambient data. The measurement procedures for each method are given in subsections (b)(3), (b)(4) and (b)(5) of this Section: |
| 3) | Using Small Blocks of Data |
| A) | The 10-minute measurement of long-term background ambient must be divided into short measurement blocks. The duration of these blocks must remain constant during the entire measurement, both when measuring the long-term background ambient and when measuring the property-line-noise-source. The duration of this measurement block in seconds, T, must divide exactly (without remainder) into 600 and must be neither greater than 100 seconds nor less than 10 seconds. |
| B) | All data for any measurement block corrupted by one or more short-term ambient transient sounds must be discarded. The number of remaining, non-discarded measurement blocks is designated NBA, where BA stands for background ambient. |
| C) | The Leq for each octave-(or 1/3 octave-) band are time-averaged on an energy basis over the NBA remaining measurement blocks to obtain average long-term background ambient Leq per band. Equation 1 (see subsection (a) (1) (E) of this Section) is used for this calculation with NBA replacing NPLNS as the number of elemental blocks to be summed. The total duration of the measurement in seconds, TBA, is given by NBA multiplied by T. |
4) Continuous Data Collection
| A) | The measuring instrument must be adjusted according to manufacturer’s instructions to continuously measure sound pressure and accumulate (i.e. record) Leq. A switch must be available to inhibit data collection whenever a short-term background transient sound occurs, (and on some instruments, a button may be available to delete the most recent, previous data). |
| B) | The switches or buttons must be used to prevent short-term background ambient sounds from corrupting the data. |
| C) | Data collection must proceed for 10 minutes. The result is the 10-minute, long-term background ambient Leq in each band. |
| D) | TBA is the number of non-inhibited measurement seconds during the 10-minute measurement period. |
| 5) | The minimum duration, for either method, TBA must be no less than 150 seconds. If TBA is less than 150 seconds, then the measurement of the long-term background ambient must continue beyond the original 10 minutes and until TBA for the total long-term background ambient measurement is greater than or equal to 150 seconds. |
| 6) | Measurement Alternatives. The long-term background ambient noise should ideally be measured at the potential violation site just before measurement of the property-line-noise-source emissions. However, turning off the property-line-noise-source may not always be possible. The following are a hierarchical order of five procedures for obtaining the long-term background ambient noise. The first four procedures involve direct measurement; the fifth procedure provides for use of tables of values obtained from extensive measurements. These are not equivalent procedures but are ordered from what is considered to be the most accurate to what is considered to be the least accurate procedure. |
| A) | Direct Measurement Procedure –1: With the property-line-noise-source (PLNS) turned off, measure the long-term background ambient noise within the hour before or within the hour after measurement of the PLNS emissions at the location where the PLNS measurements are being taken and with the measurement equipment used for the PLNS measurements. |
| B) | Direct Measurement Procedure-2: With the PLNS turned off, measure the long-term background ambient during a similar time period in terms of background ambient sound level, within one to 24 hours before, or within one to 24 hours after measurement of the PLNS emissions at the location where the PLNS measurements are being taken and with the measurement equipment used for the PLNS. |
| C) | Direct Measurement Procedure- 3: With the PLNS turned off, measure the long-term background ambient during some other acoustically similar period within one to 30 days before, or within one to 30 days after measurement of the PLNS emissions. This alternate long-term background ambient measurement time might be a Saturday night or anytime during a Sunday or holiday. The measurements would be made at the location where the PLNS measurements are being taken and with the measurement equipment (or like equipment) used for the PLNS measurement. |
| D) | Direct Measurement Procedure-4: With the PLNS turned off, measure the long-term background ambient noise during some other acoustically similar period within 30 to 90 days before, or within 30 to 90 days after measurement of the PLNS emissions. These measurements would be made at the location where the PLNS measurements are being taken and with the measurement equipment (or like equipment) used for the property-line-noise-source measurements. |
| E) | Tables of Long-Term Background Ambient Noise. Where none of the alternatives can be used, use the applicable long-term background ambient data taken from Tables A through D in Appendix A of this Part. These tables are organized by predominant land use and time of day (daytime or nighttime). There are separate tables for octave- and 1/3- octave-bands. The background environments presented in the table are based on extensive measurements conducted in the Chicago area and are divided into the five categories given below in accordance with G.L. Bonvallet, “Levels and Spectra of Traffic, Industrial, and Residential Area Noise,” Journal of the Acoustical Society of America, 23 (4), pp 435-439, July 1951; and Dwight E. Bishop and Paul D. Schomer, Handbook of Acoustical Measurements and Noise Control, Chapter 50, Community Noise Measurements, 3rd Edition, Cyril M Harris, Editor, McGraw-Hill Book Co., New York (1991). |
| i) | Category 1: Noisy Commercial and Industrial Areas. Very heavy traffic conditions, such as in busy downtown commercial areas, at intersections of mass transportation and other vehicles, including the Chicago Transit Authority trains, heavy motor trucks and other heavy traffic, and street corners where motor buses and heavy trucks accelerate. |
| ii) | Category 2: Moderate Commercial and Industrial Areas, and Noisy Residential Areas. Heavy traffic areas with conditions similar to subsection (b)(6)(E)(i) of this Section but with somewhat less traffic, routes of relatively heavy or fast automobile traffic but where heavy truck traffic is not extremely dense, and motor bus routes. |
| iii) | Category 3: Quiet Commercial and Industrial Areas, and Moderate Residential Areas. Light traffic conditions where no mass transportation vehicles and relatively few automobiles and trucks pass, and where these vehicles generally travel at low speeds. Residential areas and commercial streets and intersections with little traffic comprise this category. |
| iv) | Category 4: Quiet Residential Areas. These areas are similar to Category 3 in subsection (b)(6)(E)(iii) of this Section but, for this group, the background is either distant traffic or is unidentifiable. |
| v) | Category 5: Very Quiet, Sparse Suburban or Rural Areas. These areas are similar to Category 4 subsection (b)(6)(E)(iv) of this Section but are usually in unincorporated areas and, for this group, there are few if any near neighbors. |
| Section 910.107 | Measurement Techniques for Highly-Impulsive Sound Under 35 Ill. Adm. Code 901.104. |
| a) | Measurement of highly-impulsive sound under 35 Ill. Adm. Code 901.104 can be made in two distinct and equally valid ways, namely the general method and the controlled test method. |
| b) | General Method: The general method is to measure the 1-hour, A-weighted Leq (not the octave- or 1/3 octave-band levels) using essentially one of the two procedures described in Sections 910.105 and 910.106. |
1) The procedure using small blocks of time to collect data is as follows:
| A) | The hour must be divided into small blocks and the A-weighted Leq must be measured for each of these small blocks of time. Leq must be measured for the entire hour but data collection must be inhibited whenever a short-term background transient sound occurs. |
| B) | The duration of each block must be held constant during the hour. This duration in seconds must divide exactly into 900 and must be neither greater than 100 seconds nor less than 10 seconds. |
| C) | The data for any block corrupted by one or more short-term background ambient sounds must be discarded. |
2) The continuous data collection procedure is as follows:
A) Leq must be measured for the entire hour.
| B) | Data collection must be inhibited whenever a short-term background transient sound occurs. |
| 3) | Correction for the long-term background ambient must be accomplished using all of the other procedures and requirements enumerated in Sections 910.105 and 910.106. These requirements must be complied with to determine an A-weighted, 1-hour, background-ambient-corrected Leq for the highly impulsive property-line-noise-source under study. |
c) Controlled Test Method: For this method, the following procedures must be used:
1) General Measurement Description
| A) | The sound exposure per impulse from each separate individual impulsive source is measured. |
| B) | The total sound exposure per hour from each source is the sound exposure per event multiplied by the number of events per hour. |
| C) | The grand total sound exposure (SE) per hour is the sum of the sound exposures per hour from each of the separate individual sources. |
| D) | The reported SEL is obtained from the grand total sound exposure (SE) per hour using the following: |
SEL = 10 log (SE) + 94 [Equation 7]
| E) | The equivalent level, Leq corresponding to a SEL measured or predicted for one hour (3600 seconds) is given by: |
Leq = SEL - 10 log (3600) [Equation 8]
2) Determination of sound exposure per event must be as follows:
| A) | The sound exposure per event from each, separate, individual source must be determined by measuring the total A-weighted sound exposure for about 10 repetitions of this source. This set of about 10 measurements may be performed continuously over a short period of time, or this set of measurements may be performed over a discontinuous set of measurement periods. In either case, the total measurement duration must be less than 100 seconds. |
| B) | These separate, individual property-line-noise- source controlled measurements must be free of any short-term ambient sounds. If any short-term background transient sounds occur during these measurements, then the measurement must be repeated until measurement data, free of any corrupting short-term background ambient sounds, are obtained. |
| C) | The total measured A-weighted sound exposure for this group of about 10 repetitions must be corrected for long-term background ambient by subtracting the A-weighted long-term background ambient sound exposure. The sound exposure value subtracted must be the long-term A-weighted background ambient sound exposure per second multiplied by the number of seconds used to measure the several source repetitions. |
| D) | The reported Source: A-weighted sound exposure per event must be the total corrected sound exposure divided by the number of source repetitions measured. |
| E) | The background ambient must be measured for a short time, at least 30 seconds as near in time to the source measurements as possible, but within ½ hour. The total A-weighted long-term background ambient sound exposure per second is the total measured long-term background ambient sound exposure divided by the number of seconds of background ambient measurement. |
| F) | There must be no short-term background ambient sounds present during the measurement of the long-term background ambient. If any short-term background transient sounds occur during these measurements, then the measurements must be repeated until long-term background ambient measurement data free of any corrupting short-term background ambient sound are obtained. |
910.APPENDIX A Tables of Long-Term Background Ambient Noise
910.TABLE A. Daytime long-term background ambient Leq levels in decibels by land use categories and 1/3 octave-band level
Background Category |
Octave-Band Center Frequency (Hz) |
1 |
2 |
3 |
4 |
5 |
20 |
63 |
56 |
48 |
42 |
36 |
25 |
64 |
57 |
49 |
43 |
37 |
31 |
65 |
58 |
50 |
44 |
38 |
40 |
65 |
58 |
51 |
44 |
38 |
50 |
66 |
59 |
51 |
45 |
39 |
63 |
66 |
59 |
52 |
46 |
40 |
80 |
67 |
60 |
52 |
46 |
40 |
100 |
68 |
60 |
53 |
47 |
41 |
125 |
67 |
59 |
52 |
46 |
40 |
160 |
66 |
59 |
52 |
46 |
40 |
200 |
66 |
58 |
51 |
45 |
39 |
250 |
65 |
58 |
50 |
44 |
38 |
315 |
64 |
57 |
49 |
43 |
37 |
400 |
63 |
55 |
48 |
42 |
36 |
500 |
62 |
54 |
46 |
40 |
34 |
630 |
61 |
53 |
44 |
38 |
32 |
800 |
60 |
51 |
42 |
36 |
30 |
1000 |
58 |
49 |
40 |
34 |
28 |
1250 |
56 |
47 |
38 |
32 |
26 |
1600 |
54 |
45 |
36 |
30 |
24 |
2000 |
52 |
43 |
33 |
28 |
21 |
2500 |
50 |
41 |
30 |
25 |
19 |
3150 |
49 |
39 |
28 |
23 |
17 |
4000 |
48 |
37 |
25 |
20 |
15 |
5000 |
46 |
35 |
23 |
18 |
13 |
6300 |
44 |
33 |
21 |
16 |
10 |
8000 |
43 |
31 |
19 |
14 |
8 |
10,000 |
41 |
29 |
17 |
12 |
6 |
12,500 |
39 |
27 |
15 |
10 |
4 |
910. APPENDIX A Tables of Long-Term Background Ambient Noise
910.TABLE B. Nighttime long-term background ambient Leq levels in decibels by land use categories and 1/3 octave-band level
Background Category |
Octave-Band Center Frequency (Hz) |
1 |
2 |
3 |
4 |
5 |
20 |
53 |
48 |
43 |
37 |
31 |
25 |
54 |
49 |
44 |
38 |
32 |
31 |
55 |
50 |
45 |
39 |
33 |
40 |
55 |
50 |
46 |
39 |
33 |
50 |
56 |
51 |
46 |
40 |
34 |
63 |
56 |
51 |
47 |
41 |
35 |
80 |
57 |
52 |
47 |
41 |
35 |
100 |
58 |
52 |
48 |
42 |
36 |
125 |
57 |
51 |
47 |
41 |
35 |
160 |
56 |
51 |
47 |
41 |
35 |
200 |
56 |
50 |
46 |
40 |
34 |
250 |
55 |
50 |
45 |
39 |
33 |
315 |
54 |
49 |
44 |
38 |
32 |
400 |
53 |
47 |
43 |
37 |
31 |
500 |
52 |
46 |
41 |
35 |
29 |
630 |
51 |
45 |
39 |
33 |
27 |
800 |
50 |
43 |
37 |
31 |
25 |
1000 |
48 |
41 |
35 |
29 |
23 |
1250 |
46 |
39 |
33 |
27 |
21 |
1600 |
44 |
37 |
31 |
25 |
19 |
2000 |
42 |
35 |
28 |
23 |
16 |
2500 |
40 |
33 |
25 |
20 |
14 |
3150 |
39 |
31 |
23 |
18 |
12 |
4000 |
38 |
29 |
20 |
15 |
10 |
5000 |
36 |
27 |
18 |
13 |
8 |
6300 |
34 |
25 |
16 |
11 |
5 |
8000 |
33 |
23 |
14 |
9 |
3 |
10,000 |
31 |
21 |
12 |
7 |
1 |
12,500 |
29 |
19 |
10 |
2 |
|
910. APPENDIX A Tables of Long-Term Background Ambient Noise
910.TABLE C. Daytime long-term background ambient Leq levels in decibels by land use categories and octave-band level
Background Category |
Octave-Band Center Frequency (Hz) |
1 |
2 |
3 |
4 |
5 |
31 |
70 |
63 |
55 |
49 |
43 |
63 |
71 |
64 |
57 |
51 |
45 |
125 |
72 |
64 |
57 |
51 |
45 |
250 |
70 |
63 |
55 |
49 |
43 |
500 |
67 |
59 |
51 |
45 |
39 |
1000 |
63 |
54 |
45 |
39 |
33 |
2000 |
57 |
48 |
38 |
33 |
26 |
4000 |
53 |
42 |
30 |
25 |
20 |
8000 |
48 |
36 |
24 |
19 |
13 |
910. APPENDIX A Tables of Long-term Background Ambient Noise
910.TABLE D. Nighttime long-term background ambient Leq levels in decibels by land use categories and octave-band level
Background Category |
Octave-Band Center Frequency (Hz) |
1 |
2 |
3 |
4 |
5 |
31 |
60 |
55 |
50 |
44 |
38 |
63 |
61 |
56 |
52 |
46 |
40 |
125 |
62 |
56 |
52 |
46 |
40 |
250 |
60 |
55 |
50 |
44 |
38 |
500 |
57 |
51 |
46 |
40 |
34 |
1000 |
53 |
46 |
40 |
34 |
28 |
2000 |
47 |
40 |
33 |
28 |
21 |
4000 |
43 |
34 |
25 |
20 |
15 |
8000 |
38 |
28 |
19 |
14 |
8 |