Speech Intelligibility in Design Agawam MA

Source: PRO AV Magazine
Publication date: December 1, 2006

By Pat Brown

The original purpose of sound reinforcement was to deliver the spoken word to large groups of people. The design and installation of early systems was an engineering endeavor with objective performance criteria. Much research was done to quantify the requirements for intelligible speech with regard to the sound system and the auditorium's acoustics. Textbooks were written early in the last century that contained the necessary math and physics tools for attaining accurate speech reproduction in rooms of all types. Certainly the practitioners of that day expected others to build on their foundation. Surely the performance of speech systems would steadily improve with time. The eventual result would be excellent speech intelligibility (SI) in venues of all types.

Unfortunately, this hasn't been the case. Poor SI in public spaces is the norm rather than the exception. It's rare to be able to understand an announcement anywhere without having to strain the ear. It seems that the ground work laid by the audio fathers has been forgotten. We live in an age of amazing signal processing power, yet SI in spaces of all types continues to decline. There are some simple reasons for this.

Most people hone their listening skills in small, acoustically-friendly rooms with relatively low noise floors. This doesn't prepare one to work in large spaces.

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