period two

Sound Perception and

Rating Methods

notes

Response to Tones

Figure 21

Additionally, tones evoke a particularly strong response. Recall that a tone is a sound that occurs at a single frequency. Chalk squeaking on a blackboard, for example, produces a tone that is extremely irritating to many people.

Single-Number Rating Methods

IA-, B-, and C-weighting

INoise criteria (NC) curves

IRoom criteria (RC) curves

ISones

IPhons

Figure 22

Single-Number Rating Methods

The human ear interprets sound in terms of loudness and pitch, while electronic sound-measuring equipment interprets sound in terms of pressure and frequency. As a result, considerable research has been done in an attempt to equate sound pressure and frequency to sound levels as they are perceived by the human ear. The goal has been to develop a system of single-number descriptors to express both the intensity and quality of a sound.

With such a system, sound targets can be established for different environments. These targets aid building designers in specifying appropriate acoustical requirements that can be substantiated through measurement. For example, a designer can specify that “the background sound level in the theater

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Trane TRG-TRC007-EN manual Response to Tones, Single-Number Rating Methods