IEC Acoustic Standard IEC 61400-11

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Calculate L 70% for Classification Within each critical band every spectral line is classified as tone, masking, or neither Calculate L 70% level The energy average of the 70% of spectral lines in the critical band with the lowest spl levels L 70% = 33.13 dB A Calculate the criterion level, L 70% + 6 dB A = 39.13 dB A sound pressure level (dB A) NATIONAL RENEWABLE ENERGY LABORATORY 50 45 40 35 30 25 20 15 10 5 0 198 201 204 207 210 213 216 219 222 225 228 231 234 237 240 243 246 249 252 255 258 261 264 267 270 273 276 279 282 285 288 291 294 297 300 frequency (Hz) Freq (Hz) spl (dB A) 10^0.1*spl 198 25.30 338.67 201 25.50 354.59 204 26.02 399.88 270 26.37 433.42 273 26.79 477.90 291 27.10 512.81 288 27.38 546.63 300 27.46 557.78 276 27.61 576.47 285 27.67 584.37 294 27.68 586.63 282 27.74 594.64 267 27.78 599.23 297 27.91 617.72 279 28.68 737.67 207 29.15 822.10 261 29.38 866.01 258 30.45 1108.94 264 30.78 1197.30 210 32.15 1642.39 255 35.09 3231.56 213 37.62 5781.61 219 39.75 9447.28 222 39.86 9678.80 216 39.88 9733.16 228 40.31 225 41.20 252 41.22 237 42.31 231 42.48 243 43.21 240 43.43 246 43.50 234 43.87 249 45.44 sum/n 2057.10 10*log10 33.13
Classify ‘Masking’ A line is classified as ‘masking’ if its level is less than the criterion level L 70% + 6 dB. L pn,avg is then the energy average of all ‘masking’ lines. sound pressure level (dB A) 50 45 40 35 30 25 20 15 10 5 0 L pn,avg = 30.11 dB A 198 201 204 207 210 213 216 219 222 225 228 231 234 237 240 243 246 249 252 255 258 261 264 267 270 273 276 279 282 285 288 291 294 297 300 frequency (Hz) NATIONAL RENEWABLE ENERGY LABORATORY masking L pn,avg Freq (Hz) spl (dB A) Classification 10^0.1*spl 198 25.30 masking 338.7 201 25.50 masking 354.6 204 26.02 masking 399.9 207 29.15 masking 822.1 210 32.15 masking 1642.4 213 37.62 masking 5781.6 216 39.88 0 219 39.75 0 222 39.86 0 225 41.20 0 228 40.31 0 231 42.48 0 234 43.87 0 237 42.31 0 240 43.43 0 243 43.21 0 246 43.50 0 249 45.44 0 252 41.22 0 255 35.09 masking 3231.56 258 30.45 masking 1108.94 261 29.38 masking 866.01 264 30.78 masking 1197.30 267 27.78 masking 599.23 270 26.37 masking 433.42 273 26.79 masking 477.90 276 27.61 masking 576.47 279 28.68 masking 737.67 282 27.74 masking 594.64 285 27.67 masking 584.37 288 27.38 masking 546.63 291 27.10 masking 512.81 294 27.68 masking 586.63 297 27.91 masking 617.72 300 27.46 masking 557.78 sum/n 1025.83 10*log10 30.11
Page 1 and 2: Part I Acoustic Testing Stepping Th
Page 3 and 4: 1 Scope General description and pur
Page 5 and 6: 3 Definitions and 4 Symbols and Uni
Page 7 and 8: 6 Instrumentation Required acoustic
Page 9 and 10: 6 Instrumentation Acoustical calibr
Page 11 and 12: 6 Instrumentation Traceable Calibra
Page 13 and 14: 7 Measurements and Measurement Posi
Page 19 and 20: 8 Data Reduction Procedures Wind sp
Page 21 and 22: 8 Data Reduction Procedures Apparen
Page 23 and 24: Look at NoiseLab Setup Calibration
Page 25 and 26: Filtering for Valid Data - Listen f
Page 27 and 28: Binning and Averaging After binning
Page 29 and 30: Background Correction Calculate the
Page 31 and 32: NATIONAL RENEWABLE ENERGY LABORATOR
Page 33 and 34: One-Third Octave Levels Sound press
Page 35 and 36: Tonality To begin - Two minutes of
Page 37: Determine Critical Bandwidth Calcul
Page 41 and 42: Determination of Tone Level The sou
Page 43 and 44: Determination of Masking Level Calc
Page 45 and 46: Determination of Tonality The diffe
Page 47: Tonality can be complicated and the

IEC Acoustic Standard IEC 61400-11

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