Following preliminary research for a major aircraft manufacturer, Hayes McKenzie carried out further and more definitive research in association with the Institute of Sound & Vibration Research, at the University of Southampton, on tonal content of aircraft noise. Essentially, the research shows that the characteristic 'buzz saw' noise, exhibited by some modern jet aircraft on take-off, is not picked up as 'tonal' by the measures which have been used for quantification and certification of aircraft noise since the 1960s. Alternative methods are proposed in the paper as a first step towards correcting this.
There was much discussion among interested parties following the publication of a report for the UK Government which recommended a 'penalty scheme' for regulating AM but little information on how to use it. This paper, presented by Malcolm and others, discusses different factors which require additional consideration when considering a potential penalty to be used in combination with the IoA AM noise working group method for quantifying AM.
The IoA AM Noise Working Group method for quantifying amplitude modulation (AM) in wind turbine noise has allowed analysis of AM from wind turbines to be carried out at various sites over long periods of operations. Most of these sites are existing wind farms without AM planning controls and, therefore, although an agreed assessment method is available, the data can be presented in different ways. This paper presents analysis of data from different sites by Malcolm, Tom and others and the observations which resulted from this analysis.
The UK Institute of Acoustics November/December 2017 Monthly Bulletin contains this article, contributed to by Andy McKenzie et al, presenting proposed wording for a planning condition on noise for wind farms, or individual wind turbines, which takes account of amplitude modulation within the noise charecter.