Evaluating Room Acoustics for Speech Intelligibility

Caitlin R Kunchur

doi:10.4236/ojapps.2019.97048

Abstract

Room acoustics play an important role in the intelligibility of speech. The main aspect of acoustics that is usually studied is the duration of the reverberation decay, since a long decay causes a blurring of phonemes. However, other parameters of the acoustics such as the strength of the reverberation can actually improve intelligibility. These factors do not receive the same attention. In many common practical situations such as classrooms and residential rooms, it would be of value to quantitatively study the acoustics to optimize the room’s function, but this is not done routinely due to the expected expense or difficulty involved. This research explores inexpensive first-principle methods to quantitatively measure three key parameters of a room’s acoustics: the reverberation decay time RT60, the reverberant intensity IR, and the room’s total absorption A. The required equipment includes two laptops installed with certain free softwares. Generation of the required noise signal and level detection are carried out using the REW software, and long-duration recordings are carried out using the Audacity software. The procedures are simple enough to be performed without specialized training and do not require specialized equipment, only commonly available household resources. This research also sheds light on the fact that not all reverberation is bad and that strong but short-duration reverberation can enhance communication. This information can be expected to benefit schools and other venues where speech intelligibility is vital.

Highlights

Introduction and BackgroundSound reaches a listener in two ways: through direct sound and reflected sound
The main aspect of acoustics that is usually studied is the duration of the reverberation decay, since a long decay causes a blurring of phonemes
Reflected sound falls into various categories of which three broad ones [1] [2] [3] [4] are: 1) early (30 ms) single reflections, which are distinguishable as echoes, and 3) reverberation, which is the forest of slowly decaying multiple reflections within the room

Summary

Introduction

Introduction and BackgroundSound reaches a listener in two ways: through direct sound and reflected sound. If the sound is more concentrated in one direction, there will be an additional factor (>1) for that direction. This relationship applies to the direct sound and is altered by reflected sound. Reflected sound falls into various categories of which three broad ones [1] [2] [3] [4] are: 1) early (30 ms) single reflections, which are distinguishable as echoes (the minimum delay depends on the intensity), and 3) reverberation, which is the forest of slowly decaying multiple reflections within the room. The reverberant intensity for a continuous sound source depends only on the source’s power P and the absorption A of the room’s surfaces: IR

Objectives

Methods

Conclusion