TOA bs-1030 Mode D'Emploi
TOA Electronics Speaker Guide
12
Chapter 2: System Applications
Paging
Paging systems communicate voice announcements throughout a building or area. Distributing
intelligible speech is the main requirement of a paging system. Consider the following points
when designing a system for paging:
intelligible speech is the main requirement of a paging system. Consider the following points
when designing a system for paging:
•
Speech energy is concentrated in the range 350 Hz – 5 kHz. System frequency response
should be smooth and consistent in this range.
should be smooth and consistent in this range.
•
Speech intelligibility is most affected by system performance in the range 1–5 kHz.
Consistent coverage of the listening area is especially important in this frequency
range.
Consistent coverage of the listening area is especially important in this frequency
range.
•
People’s voices can vary significantly in loudness, sometimes leading to high peak
(short-term) demands on system power. Excessive distortion (due to overdriven ampli-
fiers or speakers) can reduce intelligibility by masking the critical consonant sounds.
See Sensitivity Ratings and the Decibel on page 18, Determining Maximum Output:
Sensitivity and Power Handling on page 21, and Chapter 7: Amplifier Selection to
match your speakers and amplifiers to the application.
(short-term) demands on system power. Excessive distortion (due to overdriven ampli-
fiers or speakers) can reduce intelligibility by masking the critical consonant sounds.
See Sensitivity Ratings and the Decibel on page 18, Determining Maximum Output:
Sensitivity and Power Handling on page 21, and Chapter 7: Amplifier Selection to
match your speakers and amplifiers to the application.
Additional intelligibility factors are discussed in Chapter 4: Audio Basics.
Speech Reinforcement
Sound systems that must amplify speech for extended periods of time (i.e., a meeting room or
a lecture hall) pose special challenges to the system designer. Consider the following points
when designing a speech reinforcement speaker system:
a lecture hall) pose special challenges to the system designer. Consider the following points
when designing a speech reinforcement speaker system:
•
It is important to avoid dead spots (quiet or dull-sounding areas within the listening
area) to maximize intelligibility and avoid feedback. Feedback occurs when the gain
is increased in an attempt to supply more volume to the dead areas.
area) to maximize intelligibility and avoid feedback. Feedback occurs when the gain
is increased in an attempt to supply more volume to the dead areas.
•
Using multiple mics to reinforce multiple speakers, as in a panel discussion, presents
a special challenge: Doubling the number of microphones reduces the system gain (rel-
ative volume) that can be reached before feedback by 3 dB.
a special challenge: Doubling the number of microphones reduces the system gain (rel-
ative volume) that can be reached before feedback by 3 dB.
•
If more than four microphones are used, consider employing an automatic mixer, such
as the TOA AX-1000A, to help maximize system gain.
as the TOA AX-1000A, to help maximize system gain.
•
The gain, or relative volume, that can be achieved depends on the relative positions of
the microphones, the loudspeakers, and the listeners, in combination with the acoustical
characteristics of the mics, loudspeakers, and room. Sound System Engineering is an
excellent reference for maximizing system gain (see page 9 for reference).
the microphones, the loudspeakers, and the listeners, in combination with the acoustical
characteristics of the mics, loudspeakers, and room. Sound System Engineering is an
excellent reference for maximizing system gain (see page 9 for reference).