Introduction
In this Chapter
Chapter 6
Speaker System Design Method
This chapter covers a design methodology that can be used to design a speaker system for an emergency voice/alarm communications system.
The ability to design an emergency voice/alarm communications system which is highly intelligible at a reasonable cost, represents a significant advantage to the customer. Achieving an acceptable level of intelligibility by trial and error can be extremely costly. A systematic approach to the design using basic guidelines and simple models can yield excellent results with a minimum investment of time.
It is important to understand the physical and acoustical characteristics of the space in which the system is installed. This requires rough measurements or estimates of the dimensions of the space and basic acoustical characteristics of the surfaces and furnishings. These factors determine the reverberation time which influences intelligibility. More sophisticated modeling tools provide accurate predictions of the reverberation time at any location within the modeled space. Simple calculations however, provide reasonably accurate assessments that are more than adequate for most installations.
Longer reverberation times require more care in the system design and even acoustical treatments to be applied to the room to achieve acceptable levels of speech intelligibility. The lower the reverberation time, the easier it is to provide a system with highly intelligible speech messaging.
Many spaces requiring emergency voice/alarm communications systems inherently have low reverberation such as office buildings, retail stores, etc. Acoustical treatments are rarely required and normal speaker layout rules apply. Churches, train stations, airport, etc. on the other hand usually have high reverberation times and can require very special techniques to achieve acceptable intelligibility levels. The sophisticated modeling tools may be required in these instances.
For most cases a simple calculation of reverberation time can be helpful. Once the acoustical characteristics of the room are understood, the speaker layout can be achieved.
Refer to the page number listed in this table for information on a specific topic:
Topic | See Page # |
Design Method | |
Recommendations for Maximizing System Intelligibility | |
Applying the Methods | |
Conclusion |