Speech intelligibility in rooms

This paper reviews developments in the science of speech intelligibility in rooms, and discusses the need for further work. Over the last 60 years, knowledge on this subject area of auditorium acoustics has been ascertained by observation and experiment, critically tested, systematized, and brought under a set of general principles. Objective indices are now available for measuring and predicting speech intelligibility in rooms without the need for traditional subjective testing procedures. Thus a more widespread application of intelligibility criteria in auditorium design is to be expected in future work. Parallel with the developments in objective and subjective measurement techniques, the computer prediction of reflection patterns in rooms has been developed so that speech intelligibility levels can now be ascertained during design, and acoustic faults remedied before construction commences. However, further work is needed to establish a valid basis for speech intelligibility design criteria based on objective measurements. To this end, a catalog of subjective and objective measures of speech intelligibility could be determined for a set of conditions in well-known auditoria. The result would be a relative scale of intelligibility values for use by practitioners. [Work supported by the SERC, United Kingdom.]