ERK S OFFICE
34 Section 910.100 General35
Section 910.106 Protocols for Determination of Sound Levels

RECE~VE

ERK S OFFICE

APR 122005

ILLINOIS REGISTER

PoJftjtSTATE

ion

(DOntroi

ILLINOIS

Board

POLLUTION CONTROL

BOARD

NOTICE OF PROPOSED RULEg

Heading ofPart: Measurement Procedures for the Enforcement of35 Ill. Adm. Code 900

&901

Code Citation: 35 111. Adm. Code 910

Section Numbers:

Proposed Action:

910.100

New Section

910.102

New Section

910.103

New Section

910.104

New Section

910.105

New Section

910.106

New Section

910.107

New Section

10~APPENDIXA

91O~TABLEA

NewSection

910.TABLE

New Section

910.TABLE C

New Section

910.TABLE D

New Section

Statutory Authority:

415

ILCS 5/25 and 27.

A Complete Description ofthe Subjects and Issues Involved: This rulemaking is

explained in more detail in the Board’s first notice opinion and order ofMarch 17, 2005,

R03-09, available from the address in item 11 below. The Illinois Pollution Control

Board opened this rulemaking to update Parts 901 and 910 ofits noise regulations found

in 35 Ill. Adm. Code Subtitle H. As no one proposed updates to the Board since 1987,

many ofthe sound measurement definitions and techniques in the Board’s existing rules

do not reflect present scientific standards. This is the second publication offirst notice

for this rulemaking; the Board withdrew its initial proposal (published on July 25, 2003 at

27 Ill. Reg. 11989) after deternrining that additional hearings should be held in the noise

ruiemakings in order to address issues that have been raised in public comments.

The proposed new Part 910 sets forth the measurement procedures for enforcing the

Board’s noise standards in Parts 900 and 901. These procedures are essentially based

upon the Illinois Environmental Protection Agency’s noise measurement protQcols at 35

Ill. Adm. Code 951. In addition to the measurement techniques, the proposal contains

general requirements and specific instrument requirements. The proposed Appendix A

includes tables (obtained from extensive measurements) that can be used to determine the

ILLINOIS REGISTER

POLLUTION CONTROL BOARD

NOTICE OF PROPOSED RULES

long-term background ambient noise levels in instances where direct measurements

caimot be made.

Will this proposedrule replace any emergency rule currently in effect? No

Does this rulemaking contain an automatic repeal date? No

Does this proposed rule contain incorporations by reference? No, but this rule does

reference materials incorporated by reference at 35 Ill. Adm. Code 900.106.

Are there any other proposed amendments pending on this Part? No

10)

Statement ofStatewide Policy Objectives: These proposed amendments do not create or

enlarge a State mandate as defined in Section 3(b) ofthe State Mandates Act. 30 ILCS

805/3 (1992).

11)

Time, Place, and Manner in which interested persons may comment on this proposed

rulemaking: The Board will accept written public comment on this proposal for a period

of45 days after the date of this publication. Comments should reference Docket R03-09

and be addressed to:

Dorothy M. Gunn, Clerk

Illinois Pollution Control Board

James R. Thompson Center

100 W. Randolph St.

Suite 11-500

Chicago IL 60601

Address all questions to Marie Tipsord, at 312/814-4925 or tipsorm@ipcb.state.il.us.

Request copies of the Board’s opinion and order in Docket R03-09 from DorothyM.

Guim, at 312-814-3620, or download from the Board’s Web site at www.ipcb.state.il.us.

12)

Initial Regulatory Flexibility Analysis:

Types ofsmall businesses affected: Any small business that engages in noise

consulting orthat emits noise beyond the boundaries ofits property may be

affected by this proposal.

ILLINOIS REGISTER

POLLUTION CONTROL BOARD

NOTICE OF PROPOSED RULES

Reporting, bookkeeping or other procedures required for compliance: No

changes in the reporting, bookkeeping or other procedures will be required for

compliance with this proposal.

Types ofprofessional skills necessary for compliance: Compliance with this

proposed rulemaking may require the services ofa professional noise consultant

to determine whether any noise it emits beyond the boundaries ofits property

violates these standards.

13)

Regulatory agenda on which this rulemaking was summarized:~January2005.

The full text ofthe Proposed Rules:. begins on the next page:

i~TNOTICE VERSION

JCAR35O91

TITLE

35:

ENVIRONMENTAL PROTECTION

APR

122005

SUBTITLE H: NOISE

STATE OF ILLINO

CHAPTER I: ILLINOIS POLLUTION CONTROL BOARD Pollution COntrol Bo~

PART 910

MEASUREMENT PROCEDURES FOR THE ENFORCEMENT

OF 35 ILL. ADM. CODE 900 & 901

Section

910.100

General

9 10.102

Instrumentation

910.103

Definitions

9 10.104

Measurement Techniques for 35 Ill. Adm. Code 900

910.105

Measurement Techniques for 35 Ill. Adm. Code 901

910.106

Protocols for Determination ofSound Levels

910.107

Measurement Techniques for Highly-Impulsive Sound Under 35 Ill. Adm. Code

104~

910~PPENDiX~A Tables of Long-Term Background Ambient Noise

910~TABLEA

Daytime long-term background ambient Leq levels in decibels by land use

categories and

1/3

octave-band level

910~TABLEB

Nighttime long-term background ambient Leq levels in decibels by land

use categories and ‘/~octave~bandlevels

910.TABLE C

Daytime long-term background ambient Leq levels in decibels by land use

categories and octave~bandlevel.~,

910~TABLB~D

Nighttime long-term background ambient Leq levels in decibels by land

use categories and octave~bandleve1~

AUTHORITY: Implementing and authorized by Sections 25 and 27 ofthe Environmental

Protection Act 415 ILCS

5/25

and 27

SOURCE: Adopted at 29 Ill. Reg.

effective_________________

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 determiningwhether a noise source~isin compliance with 35 III. Adni. Code 900 and 901.

Section 910.102 Instrumentation

JCAR35O91 0-0505255r01

Sound Measuring Equipment

An integrating sound level meter used alone or used in conjunction with

an octave!,hand or’A~octave4bandfilter set or a real-time sound analyzer

(octave~bandor V~octave~.band)must conform with the following

standards incorporated by reference at 35 Ill. Adm. Code 900.106:

ANSI S 1.4— 1983 (R2001) “American National Standard

Specification for Sound Level Meters~1,and ANSI S1.4 A

—

1985

“Amendment to ANSI S1.4 -~1983.”

ANSI S 1.11

1986 (R1998) “American National Standard

Specifications for Octave-Band and Fractional-Octave-Band

Analog and Digital Filters.”

ANSI S 1.6— 1984 (R2001) “American National Standard

Preferred Frequencies, Frequency Levels, and Band Numbers for

Acoustical Measurements.”

ANSI S1.8 -~~1989“American National Standard Reference

Quantities for Acoustical Levels.”

International Electrotechnical Commission, IEC 804-2000

Integrating/Averaging Sound level meters.

A magnetic tape recorder, graphic level recorder or other indicating device

used must meet the requirements ofthe Society ofAutomotive Engineers

(SAE) Recommended Practice J184 “Qualifying a Sound Data Acquisition

System,” November 1998, incorporated by reference at 35 Ill. Adm. Code

900.106~,

The laboratory calibration ofinstrumentation used for acoustic

measurement must be traceable to the National Bureau ofStandards, and

must be performed no less oftei~than once every 12 months.

For outdoor measurement4 a windscreen must be attached to the

microphone~,

Weather Measuring Equipment

An anemometer and compass or other devices must be used to measure

wind speed and direction in accordance with the manufacturer’s

recommended procedures.

JCAR3 50910-0505255r01

A thermometer, designed to measure ambient temperature, must be used in

accordance with the manufacturer’s recommended procedures.

A hygrometer must be used in accordance with the manufacturer’s

recommended procedures to measure the relative humidity.

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 900.10 1 apply to this Part.

100

101

Section 910.104 Measurement Techniques for

Iii. Adm. Code 900

102

103

Sound pressure level measurements are not required to establish a violation of 35 Ill. Adm. Code

104

900.102 (nuisance noise). However, sound pressure level measurements may be introduced as

105

corroborating evidence when alleging a violation of35 Ill. Adm. Code 900.102. If sound

106

pressure level measurements are collected, manufacturer’s instructions must be followed for the

107

equipment used and 35 Ill. Adm. Code 910.105 may be used as guidance in gathering data.

108

109

Section 910.105 Measurement Techniques for 35 Iii. Adm. Code 901

110

111

Sound

pressure level measurements must be obtained in accordance with the following

112

measurement techniques to determine whether a noise source is in compliance with 35 Ill. Adm.

113

Code 901:

114

115

Site Selection

116

117

Measurements may be taken at one or more microphone positions within

118

the appropriate receiving land. Measurement instruments must be set up

119

outdoors within the boundaries ofthe receiving land for the purpose of

120

determining whether a noise source is in compliance with 35 Ill. Adrn.

121

Code 901.

122

123

Measurement instruments must be set up not less than 25 feet (7.6 meters

124

(m)) from the property-line-noise-source. The 25-foot (7.6 m) setback

125

requirement is from the noise source and not the property line unless the

126

noise source is contiguous to the property line.

127

128

3).

Other measurement locations may be used for investigatory purposes such

129

as, but not limited to, the following:

JCAR35O91 0-0505255r01

130

131

Determining the extent of noise pollution caused by the source of

132

sound;

133

134

Determining the ambient; and

135

136

Analyzing those acoustical parameters that describe the sound

137

source.

138

139

For measurements of sound sources with no audible discrete tones,

140

microphones should not be set up less than 25 feet (7.6 m) from any

141

reflective surface that)may affect data. Ifmeasurements must be taken

142

within 25 feet (7.6 m), the effect, if any, of the reflective surface on the

143

measured data must be determined.

144

145

For measurements of sound sources with audible discrete tones,

146

microphones must not be set up less than 50 feet (15.2 m) from any

147

reflective surface that~may affect data. Ifmeasurements must be taken

148

within 50 feet

(15.2

m), the effect, if any, ofthe reflective surface on the

149

measured datamust be determined.

150

151

Objects with small dimensions (trees, posts, bushes, etc.) must not be

152

within

feet

(1.5

m) of the microphone position. Ifmeasurements must

153

be taken within

feet (1.5 m) of such objects, the effect, if any, on the

154

measured data must be determined.

155

156

Instrumentation Set Up

157

158

A tripod must be set at the chosen site. The tripod must be extended to a

159

height between 3 feet 8 inches (1.12 m) and 4 feet 10 inches (1.47 m)

160

above ground.

161

162

A microphone must be attached to the appropriate end ofa 5-foot

(1.5

163

or longer cable and must be affixed to the top ofthe tripod. The other end

164

ofthe cable must be connected to the measuring instrument~

165

166

The angle of incidence ofthe microphone must be adjusted to yield the

167

flattest frequency response in accordance with the manufacturer’s

168

specifications.

169

170

The measuring instrument must be separated from the microphone so as to

171

minimize any influence on the measurements. The cable movement must

172

be minimized during the measurement period.

JCAR35O91O-0505255r01

173

174

c)

Measurement 

Site Operation and

Instrument Calibration

175

176

Before taking sound pressure level measurements, measure and record

177

(near the measurement site):

178

179

Wind speed and direction;

180

181

Ambient temperature;

182

183

Relative humidity; and

184

185

Barometric pressure.

186

187

Turn the measuring instrument on and allow the instrument to stabilize.

188

Monitor and record the battery condition ofthe calibrator and all

189

measuring instruments.

190

191

Turn the calibrator on at its appropriate frequency. Allow the calibratorto

192

stabilize and calibrate the measuring system according to the

193

manufacturer’s specifications. After the measuring system has been

194

calibrated, remove the calibrator and attach a windscreen to the

195

microphone.

196

197

Adjust the microphone to the angle ofincidence that will yield the

198

frequencyresponse in accordance with the manufacturer’s specifications.

199

200

Measure the sound pressure level data within the limitations of subsection

201

(d) and according to the manufacturer’s recommended procedures. Other

202

sound pressure levels may be used for investigatory purposes such as, but

203

not limited to, the following:

204

205

Determining the extent ofnoise pollution caused by the source of

206

sound;

207

208

Determining the ambient; and

209

210

Analyzing those acoustical parameters that describe the sound

211

source.

212

213

While sound measurements are being taken, the operator must be

214

separated from the microphone so as to minimize any influence on the

215

measurements.

JCAR35O91 0-0505255r01

216

217

While measurements are being taken, visual and aural surveillance of

218

extraneous sound sources and varying wind conditions must be made to

219

insure that the conditions ofmeasurement are accurately known. Record

220

any variations in these parameters that may affect data. The number and

221

basis for affected data block must be recorded. When using a tape

222

recorder, voice commentary concerning conditions will be recorded on the

223

cue track.

224

225

To minimize wind effects on the microphone, sound measurements must

226

not be taken when the wind velocityis greater than 12 miles per hour

227

(5.4

mlsecond) at the microphone position.

228

229

For the purposes ofdata correction, the ambient sound at the measurement

230

site must be determined by means ofmeasurement or analysis.

231

232

.10)

After taking sound pressure level measurements, remove the windscreen

233

and attach the calibrator to the microphone. Turn the calibrator on at its

234

appropriate frequency. After allowing the calibrator to stabilize, monitor

235

and record the measuring system response. When the measuring system

236

response varies by more than

0.5

dB from the most recent field

237

calibration, the sound pressure level measurements obtained since such

238

most recent field calibration cannot be used for enforcement purposes.

239

240

11)

Before removing the calibrator from the microphone, turn the calibrator

241

off Ifthe ambient sound has not been determined by means of

242

measurement, determine 

the noise floor ofthe measuring system. Ifthe

243

noise floor is 

within 10

dB of the measured sound 

pressure level data, such

244

noise floor measurements must be recorded.

245

246

12)

At the end ofthe sound survey, monitor and record the battery condition

247

ofthe calibrator and all measuring instruments. Near the measurement

248

site, measure and record:

249

250

Windspeed and direction;

251

252

Ambient temperature;

253

254

Relative humidity; and

255

256

Barometric pressure.

257

JCAR35O91 0-0505255r01

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

13)

Record the physical and topographical description ofthe ground surface

within the vicinity ofthe measurement site, survey site location, a

description of the sound source, a diagram ofthe 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 maybe 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 datablocks must be recorded on the cue track. The original tape

recording must be preserved for subsequent evaluation. Laboratory

analyses maybe performed on magnetic tape recorded field data. A

description ofthe laboratory instrumentation and procedures must be

recorded. Analyses used in the laboratory must be correlated to field

measurement techniques.

Limiting Procedures for Specific Types ofData Acquisition

For measurements ofnon-impulsive sound with

audible discrete tones, ½~

octave~bandsound pressure levels must be obtained in determining

whether a noise source is in compliance with 35 Ill. Adm. Code 901.106.

For measurements ofnon-impulsive sound with no audible discrete tones,

octave~bandsound pressure levels must be obtained in determining

whether a noise source is in compliance with 35 Ill. Adm. Code 901.102

and 901.103.

Correction Factors

Ifnecessary, correction factors rounded to the nearest

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

JCAR35O91 0-0505255r01

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

:318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

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 ofa 1-hour Leq corrected for ambient. The following procedures

must be used:

Using small blocks:

The 1-hour interval is divided into many small blocks oftime 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.

The collected data for each block represents a block duration Leq

(or sound exposure level (SEL)) in octave~bands(or

‘/3 ~

octave~bandsif prominent discrete tones may be present).

Data for any block corruptedby one or more short-term

background transient sounds must be deleted.

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 forProperty-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.

The data for the NPLNS remaining blocks are time averaged on an

energy basis by octave (or V~octave~band)using Equation 1 below.

In this equation, two subscripts are used, ito designate time and j

to designate the specific frequency, either an octave-band or

octave~band. The raw, 1-hour Leq in the /th frequency band is

given by:

Leqi

lOlog

NPLNS

10”

~°

Equation 1

FL NS

i~1

where Leq is the Leq in the jth frequency band for the ith non..

deleted datablock.

JCAR35O91 0-0505255r01

341

342

In terms of SEL, the raw SEL in thejth frequency band is given

343

by:

(SELJ

NPLNS

344

SELJ

10log

Equation 2

345

346

The raw, 1-hour Leq in thejth frequencyband is given in terms of

347

the corresponding SELJ by:

348

349

L~~=SELj+10log~

3600

Equation3

PLNS

)

350

351

Where T is the block duration in seconds, NPLNS is the number of

352

non-discarded datablocks, and 3600 is the number ofseconds in

353

an hour.

354

355

Continuous Data Collection:

356

357

The measuring instrument must be adjusted to continuously

358

measure sound pressure and accumulate Leq for each block oftime.

359

For convenience, the hourmay be split into several smaller blocks

360

such as 10, 6-minute blocks or 4, 15-minute blocks, etc.

361

362

A switch on the measuring instrument must be available to inhibit

363

data collection whenever a short-term background transient sound

364

occurs. This switch shall be used to prevent short-term

365

background ambient sounds from corrupting the data.

366

367

Data collection must proceed for one hour. The energy average of

368

the several measured Leqij each weighted by the number ofseconds

369

actually accumulated during the ith block results in the raw, 1-hour

370

Leq in each frequency band given by:

371

NPLNS

1~!~:1

372

Leqi

10 log

~

10)

Equation 4

TPLNS

1=1

373

374

Where Leqij is the Leq in the jth frequency band for the ith large

375

block. T1 is the actual number ofseconds of “good”~lata

376

accumulated in the ith block oftime (e.g., 6 to 15 minutes); and

377

JCAR3SO910-0505255r01

NPLNS

378

TPLNS =

Equations

379

380

Minimum data collection requirements:

381

382

Initial Measurement Duration. The property-line-noise-source

383

measurements must proceed initially for one hour. Because of

384

correction for short-term background transient sounds, actual

385

reported data collection time T, in seconds, maybe less than 3600

386

seconds (one hour).

387

388

Ifsmall blocks ofdata are used for data collection, then the

389

total measurement duration in seconds, TPLNS~is given by

390

NPLNS T, where T is the length ofeach block in seconds and

391

NPLNS is the number ofnon-discarded blocks. Ifdata

392

inhibition is used for data collection, then TPLNS is the

393

number of non-inhibited seconds during the measurement

394

hour. In either case, TPLNS must be no less than 900

395

seconds.

396

397

ii)

Ifvery few blocks were used for data collection, then the

398

duration of eaCh block, T, may be too long and should be

399

reduced.

400

401

iii)

For either data collection method, sounds considered to be

402

short-term transient may actually be part ofthe long-term

403

background ambient and should be so redefined.

404

405

Extended Measurement Duration. IfTPLNS is less than 900 seconds

406

during the first hour ofmeasurements, the raw data collection

407

procedures must be appropriately modified and new measurements

408

must proceed for an additional hour. IfTPLNS after combining the

409

first and the second hour ofmeasurements is also less than 900

410

seconds, then the raw data collection must continue using the data

411

inhibition method or method employed during the second hour

412

until TPLNS is greater than or equal to 900 seconds.

413

414

Correction for Long-Term Background Ambient Sound:

415

416

The raw 1-hour Leq must be corrected for long-term background

417

ambient sound. The subsection below describes niethods to obtain

418

the long-term background ambient sound level in thejth frequency

JCAR35O910-0505255r01

419

band. The correction is dependent on the difference (in decibels)

420

between the raw, 1-hour,jth band property-line-noise-sourc~:Leqj

421

and corresponding jth band long-term background ambient sound

422

level. The correction to be applied is as follows:

423

424

Ifthe difference between the raw 1-hour Leq and the long-

425

term background ambient sound is larger than 10 decibels,

426

then the correction must be set to 0.

427

428

ii)

Ifthe difference between the raw 1-hour Leq and the long-

429

term background ambient sound difference is less than 3

430

decibels, then thejth frequency-band level, Leqj, must be set

431

equal to 0.

432

433

iii)

Ifthe difference between the raw 1-hour Leq and the long-

434

term background ambient sound is between 3 and 10

435

decibels~thenthe correction given in Table 1 below must

436

be subtracted from the raw, 1-hour property-line-noise-

437

source Leqj

438

439

Table I

440

Corrections in dB for long-term

441

background~Yambientsound

442

Difference

Correctiot

(dB)

2.3

1.7

1.3

1.0

0.7

0.6

0.5

443

444

The long-term background ambient corrected level must be the

445

property-line-noise-source Leqi reported for the jth frequency band.

446

447

Obtaining the background ambient sound level:

448

449

The background ambient must be measured for the purposes ofthis

450

Section during a 10-minute interval.

451

JCAR35O91 0-0505255r01

452

Long-term background ambient measurement procedures are similar to

453

procedures to measure the property-line-noise-source itself. Eliminating

454

short-term background ambient transient sounds from the measurement of

455

average long-term background ambient sound proceeds in a manner

456

similar to the measurement ofthe property-line-noise-source emissions

457

themselves. The two methods for measurement are: to divide the 10-

458

minute measurement into short blocks of data, or inhibit data collection

459

when short-term background transient sounds occur. The same method

460

must be used for gathering both the property-line-noise~sourcedata and

461

the corresponding long-term background ambient data. The measurement

462

procedures for each method are given in subsections (b)(3), (b)(4)~and

463

(b)(5)3ofthis Section:

464

465

Using Small Blocks ofData

466

467

The 10-minute measurement of long-term background ambient

468

must be divided into short measurement blocks. The duration of

469

these blocks must remain constant during the entire measurement,

470

both when measuring the long-term background ambient and when

471

measuring the property-line-noise-source. The duration ofthis

472

measurement block in seconds, T, must divide exactly (without

473

remainder) into 600 and must be neither greater than 100 seconds

474

nor less than 10 seconds.

475

476

All data for any measurement block corrupted by one ormore

477

short-term ambient transient sounds must be discarded. The

478

number ofremaining, non-discarded measurement blocks is

479

designated NBA, where

stands forbackground ambient.

480

481

The Leq for each octave~..(or ½~octavei~bandare time-averaged on

482

an energy basis over the NBA remaining measurement blocks to

483

obtain average long-term background ambient Leq per band.

484

Equation 1 (see subsection (a)(1)(E) ofthis Section) is used for this

485

calculation with NBA replacing NPLNS as the number of elemental

486

blocks to be summed. The total duration ofthe measurement in

487

seconds, TBA, is given by NBA multiplied by T.

488

489

Continuous Data Collection~.

490

491

The measuring instrument must be adjusted according to

492

manufacturer’s instructions to continuously measure sound

493

pressure and accumulate (i.e.~record) Leq. A switch must be

494

available to inhibit data collection whenever a short-term

JCAR35O91 0-0505255r01

495

background transient sound occurs, (and on some instruments, a

496

button may be available to delete the most recent, previous data).

497

498

The switches or buttons must be used to prevent short-term

499

background ambient sounds from corrupting the data.

500

501

Data collection must proceed for 10 minutes. The result is the 10-

502

minute, long-term background ambient Leq in each band.

503

504

TBA is the number ofnon-inhibited measurement seconds during

505

the 10-minute measurement period.

506

507

The minimum duration, for either method, TBA must be no less than 150

508

seconds. If TBA is less than 150 seconds, then the measurement ofthe

509

long-term background ambient must continue beyond the original 10

510

minutes and until TBA for the total long-term background ambient

511

measurement is greater than or equal to 150 seconds.

512

513

Measurement Alternatives. The long-term background ambient4rloise

514

should ideally be measured at the potential violation site just before

515

measurement ofthe property-line-noise-source emissions. However,

516

turning offthe property-line-noise-source may not always be possible.

517

The following are a hierarchical order offive procedures for obtaining the

518

long-term background ambient noise. The first four procedures involve~

519

direct measurement; the fifth procedure provides for use oftables of

520

values obtained from extensive measurements. These are not equivalent

521

procedures but are ordered from what is considered to be the most

522

accurate to what is considered to be the least accurate procedure.

523

524

Direct Measurement Procedure~J:With the property-line-noise-

525

source (PLNS) turned off, measure the long-term background

526

ambient noise within the hour before or within the hour after

527

measurement ofthe PLNS emissions at the location where the

528

PLNS measurements are being taken and with the measurement

529

equipment used for the PLNS measurements.

530

531

Direct Measurement Procedure-2: With the PLNS turned off,

532

measure the long-term background ambient during a similar time

533

period in terms ofbackground ambient sound level, within one ~to

534

~24ihours before, orwithin one~to24~hoursafter measurement of

535

the PLNS emissions at the location where the PLNS measurements

536

are being taken and with the measurement equipment used for the

537

PLNS.

JCAR35O91 0-0505255r01

538

539

C)

Direct Measurement Procedure-3: 

With the PLNS turned off,

540

measure the long-term background ambient during some other

541

acoustically similar period within one~to~30~daysbefore, orwithin

542

one~to~30~days after measurement of the PLNS emissions. This

543

alternate long-term background ambient measurement time might

544

be a Saturday night or anytime during a Sunday or holiday. The

545

measurements would be made at the location where the PLNS

546

measurements are beingtaken and with the measurement

547

equipment (or like equipment) used for the PLNS measurement.

548

549

Direct Measurement Procedure-4: With the PLNS turned off,

550

measure the long-term background ambient noise during some

551

other acoustically similar period within~3O.td~9Q~days before, or

552

within~30~to~90~daysaftermeasurement ofthe PLNS emissions.

553

These measurements would be made at the location where the

554

PLNS measurements are being taken and with the measurement

555

equipment (or like equipment) used for the property-line-noise-

556

source measurements.

557

558

Tables ofLong-Term Background Ambient Noise. Where none of

559

the alternatives can be used, use the applicable long-term

560

background ambient datataken from Tables A through D in

561

Appendix A ofthis Part. These tables are organized by

562

predominant land use and time ofday (daytime or nighttime).

563

There are separate tables for octave~and ‘/~octave:thands.The

564

background environments presented in the table are based on

565

extensive measurements conducted in the Chicago area and are

566

divided into the five categories given below in accordance with

567

G.L~Bonva11et,“Levels and Spectra ofTraffic, Industrial, and

568

Residential Area Noise,” Journal ofthe Acoustical Society of

569

America, 23 (4), pp 435-439, July~1951;and Dwight E. Bishop and

570

Paul D. Schomer, Handbook ofAcoustical Measurements and

571

Noise Control, Chapter

50,

Community Noise Measurements,

3Tc~

572

Edition, Cyril M Harris, Edito~McGraw-Hill Book Co., New

573

York (1991).

574

575

Category 1: Noisy Commercial’ and Industrial Areas. Very

576

heavy traffic conditions~such as in busy downtown

577

commercial areas, at intersections ofmass transportation

578

and other vehicles~including the Chicago Transit Authority

579

trains, heavy motor trucks and other heavy traffic, and

JCAR35O9 1 0-0505255r01

580

street corners where 

rnotor~busesand heavy trucks

581

accelerate.

582

583

ii)

Category 2: Moderate Commercial and Industrial Areas,

584

and Noisy Residential Areas. Heavy traffic areas with

585

conditions similar to subsection (b)(6)(E)(i) ofthis Section

586

but with somewhat less traffic, routes ofrelatively heavy or

587

fast automobile traffic but where heavy truck traffic is not

588

extremely dense, and motor bus routes.

589

590

iii)

Category 3: Quiet Commercial and Industrial Areas, and

591

Moderate Residential Areas. Light traffic conditions where

592

no mass transportation vehicles and relatively few

593

automobiles and trucks pass, and where these vehicles

594

generally travel at low speeds. Residential areas and

595

commercial streets and intersections with little traffic

596

comprise this category.

597

598

iv)

Category4: Quiet Residential Areas. These areas are

599

similar to Category 3 in subsection (b)(6)(E)(iii) ofthis

600

Section but1for this group., the background is either distant

601

traffic or is unidentifiable.

602

603