Investigating the potential of exploiting the missing fundamental phenomenon for low frequency noise control at music events

The control of noise at outdoor events is an increasingly prominent area of focus, possibly precipitated by the rising levels of low frequency content associated with many genres of modern music, and by more festivals being hosted at venues in heavily populated areas. Although there are many techniques for controlling and mitigating noise from live music events, there is no one solution that works every time. This paper investigates the potential of exploiting the psychoacoustic ‘missing fundamental’ phenomenon as a method of low frequency noise control. Following a review of current UK event noise management guidance, the deviations from that guidance that occur in practice are explored, revealing a large variation in the limits that are applied. The phenomenon of the ‘missing fundamental’ is then discussed, explaining how the perception of pitch is maintained even when the fundamental frequency is removed. For four different test spectra, theoretical calculations are presented which demonstrate a reduction in the overall Z-weighted and C-weighted levels at an offsite location when the fundamental frequency is either reduced in amplitude or completely removed at source. Outdoor propagation measurements carried out at a small music festival are shown to be consistent with the theoretical predictions and confirm the potential noise mitigation benefits for nearby residents of reducing the fundamental at source, while still maintaining the on-site experience of event attendees.