Linking design decisions to speech intelligibility

Abstract

What is the largest classroom that will support unamplified communication? What design attributes and acoustical conditions contribute to speech intelligibility, and how much should each design attribute be weighted when predicting speech transmission index (STI)? This line of inquiry aims to correlate room design and mechanical equipment (HVAC) design to speech intelligibility (STI) in university lecture rooms. It seeks to link the STI of classrooms at Virginia Tech to ambient noise levels, reverberation time, impulse response characteristics, room volume, number of seats, distance to nearest HVAC terminal device, receiver location, and speaker source power. Ambient noise measurements and STI will be mapped on a 1 m x 1 m grid for a subset of the measured rooms to visualize the noise on the listener plane and better estimate the haptic component of signal-to-noise ratio in the spaces. The research also will explore quirks in the STI measurement itself, including differences between the direct and indirect measurement methods, differences permitted for test speech level, and differences from seat to seat within a single room.