Falling coins, striking matches, and whispering voices to demonstrate the acoustics of an open air amphitheatre

Abstract

Part of the Ancient Acoustics research project was to measure a dense grid of impulse responses in three ancient amphitheatres in accordance with the ISO 3382 standard. In this conference paper, the measurements performed in the theatre of Epidaurus at 264 receiver positions are used to study the “signal” to “noise” ratios (SNR) for typical low energy sound sources such as falling coins, striking matches and whispering voices, described in travel guides and used by tourists to confirm or disclaim the exceptional acoustical quality of open air amphitheatres. The “signal” is obtained from sound power measurements of these sources in a reverberation room, combined with the measured Sound Strength G at every position in the theatre. To determine G, asynchronous impulse response measurements were carried out using two dodecahedron sound sources playing stimulus signals simultaneously. The measured background noise was used as the “noise” in the SNR. Besides, speech intelligibility measurements have been carrie...