6. SummaryA good intelligibility test is one in which the audience is asked to distinguish each word from a list of single syllable non-connected words. The audience should be well dispersed throughout the enclosed area. Superimposed above the word sounds should be a controlled level of masking noise, which simulates the background noise in the environment of the area. For a good hall the score should vary from 90% with no masking to at least 70 % with 15 dBA overlaid sound.
Surface treatment to the walls to control reverberation time should not be applied and any arbitrary position in the area. This task has to be planned. However, in general to reduce time delayed reverberant sound and direct sound application on the sidewalls is the normal practice.
Many halls have their speech reinforcement systems badly planned. The selection of the microphone and the placement of speakers must be given serious consideration. If in doubt use column speakers as opposed to a single high level speaker for optimum directionality and enchantment of the speech above the reverberant speech.
