The use The use of of synthesised synthesised or or actual - - PowerPoint PPT Presentation

▶
the use the use of of synthesised synthesised or or
SMART_READER_LITE
LIVE PREVIEW

The use The use of of synthesised synthesised or or actual - - PowerPoint PPT Presentation

Jan 02, 2023 182 likes •338 views

23rd International Congress on Acoustics The use The use of of synthesised synthesised or or actual actual wind wind turbine turbine noise noise for for subjective subjective evaluation evaluation purposes purposes Steven Cooper

slide-1
SLIDE 1

The The use use of

  • f synthesised

synthesised or

  • r actual

actual wind wind turbine turbine noise noise for for subjective subjective evaluation evaluation purposes purposes

Steven Cooper

23rd International Congress on Acoustics

slide-2
SLIDE 2

CBW Turbine 13 at 14% power

FFT vs Time (0-1 kHz, 400 lines) FFT (0-1 kHz, 400 lines) A-weighted Time Splice

slide-3
SLIDE 3

Kelley N.D., Hemphill R.R. and McKenna H.E. A Methodology for Assessment of Wind Turbine Noise

Turbine noise emission components with building and human body resonances superimposed

slide-4
SLIDE 4

Cape Bridgewater Wind Farm, House 87 Bedroom, 5:30 am 22 May 2014, Leq, 10 minute FFT (1600 lines)

0 – 25 Hz 0 – 1 kHz

slide-5
SLIDE 5

100 Hz 100 ms Burst

40m 80m 0.12 0.16 0.2 0.24 0.28 0.32 0.36 [s]

  • 0.24
  • 0.2
  • 0.16
  • 0.12
  • 80m
  • 40m

40m 80m 0.12 0.16 0.2 0.24 [V] Generator (Real)

100 200 300 400 500 600 700 800 900 1k [Hz]

  • 100
  • 80
  • 60
  • 40

[dB/1 V] 100Hz (100ms, 1Hz Burst) - Generator (Free Running Trigger) (Real) 4 8 12 16 20 24 [Hz]

  • 100
  • 90
  • 80
  • 70
  • 60

[dB/1 V] 100Hz (100ms, 1Hz Burst) - Generator (Real)

slide-6
SLIDE 6
slide-7
SLIDE 7

Shirley Wind Farm Report with manufacturers frequency response of speaker used in Crichton paper shown in

  • range trace
slide-8
SLIDE 8

Walker B & Celano J “Progress Report on Synthesis of Wind Turbine Noise and Infrasound”

Walker Synthesised Waveform Original Waveform Original FFT (1600 lines, 0-25 Hz)

slide-9
SLIDE 9
slide-10
SLIDE 10
slide-11
SLIDE 11

Tonin Results (synthesised) Cooper Results (field measurements) Waveform FFT (0-25 Hz, 1600 lines)

slide-12
SLIDE 12

Annexure D of ANSI/ASA S12.9-2016/Part 7 “Advanced Signal Processing Techniques”

It has been observed (Bray, Swinbanks, Walker, et al) that for complex low-frequency signals (those comprising multiple frequencies), the temporal relationship between the components can have a significant influence on their subjective assessment. (Indeed, al one needs do is listen to the difference between a gun-shot and an extended Galois sequence signal to observe the two signals with the exact same spectrum can sound dramatically dissimilar.)

slide-13
SLIDE 13

Line Array Speaker System (2.5 inch drivers) showing the Cape Bridgewater signal

slide-14
SLIDE 14

Conclusion

  • Testing of wind turbine infrasound should use actual signals of wind

turbines and not a tone or a synthesised signal

  • Infrasound levels attributed to wind turbine noise are less than the

threshold of audibility for constant tones and therefore should be inaudible.

  • Why test for infrasound only when wind turbine noise contains frequencies

in the audible spectrum?

  • The infrasound signature obtained by narrowband FFT analysis is the result
  • f an analysis of transient pulses that can be derived by modulating sounds
  • f much higher frequency
  • For testing of wind turbine noise (including infrasound?) in a more practical

sense, would be easier and realistic to simply use wave file recordings