IOA AMWG

EWEA Wind Turbine Sound 2014

The Institute of Acoustics Working Group

on Wind Turbine Amplitude Modulation:

Progress towards a preferred assessment

methodology

Malmö 9th December 2014

Gavin Irvine, Ion Acoustics Ltd

UK History

2007 2009 – 2015 Denbrook

IOA AMWG

More History

R-UK Study R-UK Planning Condition

IOA AMWG

Structure

Institute of Acoustics

IoA Council

Wind Turbine Noise Group

Amplitude Modulation Working Group

Working Group Members

• Gavin Irvine, Ion Acoustics (Chair)

• Matthew Cand, Hoare Lea Acoustics

• Bob Davis, Robert Davis Associates

• Dave Coles, 24 Acoustics

• Sam Miller, Parsons Brinckerhoff

• Tom Levet, Hayes McKenzie Partnership

• John Shelton, AcSoft

• Jeremy Bass, RES

• David Sexton, West Devon Borough Council

• Geoff Leventhall

IOA AMWG

The Problem:

IOA AMWG

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What is the AM Rating?

Why an agreed method?

• For use in planning conditions, either as a

stand-alone threshold or with a penalty

scheme

• For research purposes and mitigation

studies, to provide a consistent method for

trialling different techniques

• For noise nuisance investigations

IOA AMWG

Scope of Work• Undertake a literature review of available research and evidence on

amplitude modulation and current methods in use, as appropriate; and on

psycho-acoustic effects of AM

• Consider the design parameters for an AM metric and assessment method to

be used in the UK;

• Consider the various metrics and methodologies available to describe AM,

and develop a preferred option if possible, or identify alternatives for the IOA

membership to consider;

• Produce a first draft of a consultation document with explanatory notes /

justifications for consultation;

• Consult the IOA membership and where appropriate other relevant technical

experts on the draft guidance document;

• Consider the consultation responses and if appropriate, produce a final

Supplementary Guidance Note and / or consider the need for further

research;

• Provide software, if possible, to allow the analysis of AM data.

IOA AMWG

Literature Review• Fastl H. and Zwicker E. Psycho-Acoustics: Facts and Models . (Chapter 10 –

Fluctuation Srength). 199. Springer.

• Shin S-H. (2008). Comparative study of the commercial software for sound

quality analysis. . Acoustic Science and Technology 29: 221-228.

• Cheong C and Joseph P. (2014.) Cyclostationary spectral analysis for the

measuement and prediction of wind turbine swishing noise. Journal of Sound

and Vibration 333: 3153-3176.

• Cooper J. and Evans T. (2013). Automated detection and analysis of amplitude

modulation at a residence and wind turbine. Proc. ACOUSTICS 2013. Victor

Harbor, Australia.

• Di Napoli C. (2009). Case Study: Wind Turbine Noise in a small and quiet

community in Finland. 3rd International Meeting on Wind Turbine Noise.

Aalborg.

• Di Napoli C. (2011). Long distance Amplitude Modulation of Wind Turbine

Noise. 4th International Meeting on Wind Turbine Noise. Rome. .

• Gabriel J. et al. (2013). Amplitude Modulation and Complaints about Wind

Turbine Noise. 5th International Meeting on Wind Turbine Noise. Denver.

• Larsson C. and Ohlund O. (2014). Amplitude modulation of sound from wind

turbines under various meteorological conditions. J. Acous. Soc. Am. 135(1).

• Larsson C. and Ohlund O. (2012) Variations of Sound from wind turbines

during different weather conditions. Proc. INTERNOISE 2012. New York.

Literature Review

Lenchine V. Amplituide modulation in wind turbine noise. Proc. ACOUSTICS 2009,

Adelaide, AustraliaC

Lee S. et al. Annoyance caused by amplitude modulation of wind turbine noise.

Noise Control Engineering 1 99(1) Jan-Feb 2011.

Lee S. et al. An estimation method of the amplitude modulatoin in wind turbine

noise for community assessment. 3rd International Meeting on Wind Turbine

Noise. Aalborg. June 2009.

Legarth S.V. (2007). Auralization and Assessments of Annoyance from Wind

Turbines. Proc. 2nd International Meeting on Wind Turbine Noise. Lyon.

Lundmark G. Measurement of Swish Noise. A new method. 4th International

Meeting on Wind Turbine Noise. Rome. April 2011.

Jiggins M. Subjective perception of Wind Turbine Blade Noise. M.Sc. thesis.

Heriot-Watt University. 1997.

McLaughlin D. (2011). Measurement of amplitude modulation frequency spectrum.

4th International Meeting on Wind Turbine Noise. Rome.

Seong Y. et al. (2013). An experimental study on rating scale for annoyance due to

wind turbine noise. Proc. INTERNOISE. Innsbruck.

Fukushima A, Tachibana H et al. Study on the amplitude modulation of wind

turbine noise: Part 1 – Physical investigation. Proc. INTERNOISE 2013..

Yokoyama S et al. (2013). Study on the amplitude modulation of wind turbine

noise: Part 2:. Proc. INTERNOISE 2013. Innsbruck.

Literature Review

Tachibana H et al. (2014). Nationwide field measurements of wind turbine noise in

Japan. Noise Control Engineering Jhl 62(2): 90-101.

van den Berg G.P. The Sound of High Winds: The effects of atmospheric stability

on wind turbine sound and microphone noise. Doctoral thesis, Rijksuniversetiet

van den Berg G.P. The Beat is getting stronger: The Effect of Atmospheric Stability

on Low Frequency Modulated Sounds of Wind Turbines. Journal of Low

Frequency Noise, Vibration and Active Control Vol 24, No. 1 2005.

Studies and papers by MAS Environmental - http://www.masenv.co.uk/windfarms

NSW Planning Guidelines – Wind Farms (Consultation draft). (2011). New South

Wales Department of Planning and Infrastructure

Acoustics – Wind farm Noise. New Zealand Standard NZS 6808:2010.

Wind farms environmental noise guidelines (2009). South Australia Environmental

Protection Agency.

Wind turbine amplitude modulation: research to improve understanding as to its

cause and effect. Renewable UK Limited December 2013.

Template Planning Condition on Amplitude Modulation. Renewable UK Limited,

December 2013.

The efficacy of the RUK AM condition. Renewable Energy Foundation March 2013

. http://www.ref.org.uk/publications

Persson Waye K. and Ohrstrom E. (2002. Psycho-acoustic chtracters or

relevance for Annoyance of Wind Turbine Noise. JSV 250(1) 65073

Classifying Methods

FFT

Peak to Trough

(Time)

Fluctuation Strength

Impulsivity

Standards / Conditions

Tachibana

Hybrid

Methods

Methods backed with

subjective studies

• Salford – mean

peak to trough

• Tachibana et al

DAM

• Seong, Lee –

LAMax

• Gabriel &

Hubner / Vogl

• Legarth

IOA AMWG

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Modulation Depth, dB

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B(A

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Comparing Methods

IOA AMWG – Analysis by Tom Levet, Hayes McKenzie

Comparing Methods

IOA AMWG – Analysis by Matthew Cand, Hoare Lea

IOA AMWG

• Use band-limited spectrum based on 1/3rd Octave Band Monitoring

• Contribution of BPF harmonics ??

• Allow for variation in turbine rpm

Option 1 – FFT-based Method

IOA AMWG

Option 2 – Hybrid Method – Evans and Cooper

• Objective – to measure noise from a wind farm to determine compliance with interim AM limits in NZS 6808: 2010

• Applied FFT method to detect periodic peaks related to BPF and reject non-related peaks, using time windows of varying width. Then applied peak-trough tests to time-series data identified as being WTAM dominated. Technique largely eliminated ‘false positive’ exceedances of dB(A) limit.