Category: (((—Acoustics Engineering—))))

The NC curves (Figure 6.7) were developed from the results of a series of interviews with people in offices, public spaces, and industrial spaces [21, 22]. These results showed that the main concern was the interference of noise with speech communication and listening to music, radio, and television. In order to determine the NC rating of…

The SIL is mainly used to evaluate the effect of noise on speech in situations outdoors or indoors where the environment is not too reverberant. The A‐weighted SPL can be used as a guide for the acceptability of noise in indoor situations, but it gives no indication about which part of the frequency spectrum is…

The SIL is a measure used to evaluate the effect of background noise on speech communication [17]. The SIL is the arithmetic average of the SPLs of the interfering background noise in the four octave bands with center frequencies of 500, 1000, 2000, and 4000 Hz (see ANSI S3.14–1977(R‐1986)). If the SIL of the background noise…

The articulation index (AI) is a measure of the intelligibility of speech in a continuous noise. The AI was first proposed by French and Steinberg [16] and was extended later by Beranek and Ver [17]. Speech has a dynamic range of about 30 dB in each one‐third octave band from 200 to 6000 Hz, and the long‐term root…

6.4.1 Noisiness Although the level of noise or its loudness is very important in determining the annoyance caused by noise, there are other acoustical and nonacoustical factors that are also important. In laboratory studies, people were asked to rate sounds of equal duration in terms of their noisiness, annoyance, or unacceptability [9, 10]. Using octave bands…

As discussed in Section 4.3.2 which contains an in‐depth description of the loudness of sound, the human ear does not have a uniform sensitivity to sound as its frequency is varied. Figure 4.6 in Chapter 4 shows equal loudness level contours. These contours connect together pure‐tone sounds that appear equally loud to the average listener. Recently, slightly modified contours have been…

As the level of the noise is increased, it is accompanied by an apparent increase in loudness. Loudness may be considered to be the subjective evaluation of the intensity of a noise when this evaluation is divorced from all the attitudinal, environmental, and emotional factors that may affect the listener’s assessment of the annoying properties…

People are exposed to noise during daytime and nighttime hours. During the day the noise can interfere with various activities and cause annoyance, and at night it can affect sleep. Very intense noise can even lead to hearing damage (see Chapter 4). In the daytime the activities most affected are communications that involve speech between individuals,…