Analysis and Modelling of Human Impact on Sound Reinforcement and Reproduction in Large Spaces

Optimising auditory experiences by achieving democracy of sound, providing high quality listening experiences throughout large entertainment venues, presents significant challenges. Sound systems are designed to ideally provide a consistent tonal balance despite large audience areas, complicated geometries, acoustics and often highly reverberant characteristics associated with these types of spaces. Sound system technicians heavily rely on objective measurements made in unoccupied venues and have limited methods of predicting or quantifying the system response after the introduction of audiences. This research aims to exploit the capabilities of auralisation, to allow for virtual monitoring of positions across large venues, leveraging measured unoccupied room impulse responses that have been processed to simulate occupied conditions.

Acoustic computer models can be constructed to gain insight of the behaviour of a sound system in an entertainment venue. In practice, this is often limited to the direct sound. In models which include reflections, an audiences' absorption characteristics can be included within the model to observe the effects. However, there are limited validated approaches, especially for standing audiences. In the presented work, a novel implementation of standing audiences within acoustic computer models has been developed. This method, validated against unoccupied and occupied field measurements taken in four UK arenas, has included the generation of absorption coefficient data tailored to standing audiences in different arrangements.

The prediction of occupied reverberation characteristics, a key objective of this work, was achieved using multiple linear regression, leveraging an extensive survey of calibrated acoustic computer arena models. In unseen cases, the arena volume, audience capacity, unoccupied reverberation time and occupation rate can yield an accurate prediction of reverberation changes.

A bespoke artificial occupation technique is presented which involves the manipulation of decay characteristics to emulate the reverberance of occupied spaces. This approach assists in bridging the perceptual gap between unoccupied and occupied acoustic conditions. Perceptual ABX listening tests yielded satisfactory outcomes whereby measured occupied room impulse responses were not easily distinguished compared to artificially occupied counterparts. Results suggest adequate replication akin to real-world occupied scenarios. The outcomes of this research have been distilled into tangible proof of concept applications. These applications show potential as practical tools, empowering sound system technicians, designers, audio educators and students. The combination of theoretical advancements and practical applications holds promise for increasing the democracy of sound and high quality listening experiences within large entertainment venues.

Acoustic computer models were also leveraged to investigate the impact of spectators on sports stadia intelligibility. The contribution of level-masking in high sound pressure level conditions has been shown to be significant, and alongside crowd noise, counteracts the additional absorption from spectators. This work is cited in BS 7827.