Influences on Intelligibility, Continued
Distortion | Distortion of the speech waveform can come from many sources, however it is usually exhibited |
| by an overdriven signal, causing the peaks of the waveform to be clipped. “Clipping” is caused by |
| some part of the electrical signal path within the fire alarm system exceeding the capacity of the |
| components. The most common cause of clipping is improper use of the microphone, where the |
| operator is shouting into the microphone, overdriving the system. Because clipping itself does not |
| reduce modulations, the intelligibility effects of clipping are generally not as severe as noise and |
| reverberation effects. A properly installed, operated, and maintained Simplex Fire Alarm Audio |
| System has minimal distortion and reproduces speech with excellent clarity. |
Microphone Technique
Proper microphone technique can be a major speech intelligibility factor in emergency voice/alarm communications systems. Unfortunately, this is one area over which the system designer has no control. Although this is not normally considered during the measurement of speech intelligibility or during system acceptance testing, it should be considered in the training and use of the system.
For this reason, when possible, use of
