Speech intelligibility in restaurants—A reverberation or early reflection problem?

Several acoustic factors coincide to create hostile sonic environments in restaurants—including noise & reverberation. Reverberation time is often cited as the cause of noise build up and resultant lack of speech ineligibility in restaurants and similar spaces. This paper suggests that in smaller dining rooms and spaces for socializing, it is the generation of strong early reflections and occupation density rather than reverberation time that are the key factors. Ceiling height is also shown to be a significant factor. The paper presents an acoustic analysis of three dining/socializing spaces and the effect that the application of acoustic treatment has on the ambient noise levels and potential intelligibility. A rough rule of thumb for the volume per person required for satisfactory speech conditions is also presented together with case history data.