Illustrations

Figure 1. Normal equal-loudness contours for pure tones

Figure 2. Standard A, B, C and D filter characteristics for sound level meters (IEC 179, 1973a; IEC 179a, 1973b)

Figure 3. Hearing loss as a function of duration in noise exposure in years. Mean audio-grams for 203 miners, best ear tested. (a < 1 year; b = 1-5 years; c = 6-10 years; d = 11-20 years; e = 21-30 years; f > 30 years; From: B. Johansson, 1952.)

Figure 4. Percentage of workers with hearing impairment (average hearing loss at 1, 2, and 3 kHz > 25 dB) [From: US National Institute for Occupational Safety and Health (Lampert & T.L. Henderson, 1973)].

Figure 5. Percentage of exposed population that will incur no more than 5 dB NIPTS shown as a function of exposure level. Population ranked by decreasing ability to hear at 4,000 Hz. [US EPA, 1974b].

Figure 6. Maximum distances outdoors over which conversation is considered to be satisfactory intelligible in steady noise (U.S. EPA, 1974b)

Figure 7. Normal voice intelligibility as a function of the steady background sound level in a typical living room (U.S. EPA, 1974b)

Figure 8. Normal distribution of annoyance scores (Ollerhead, 1973).

Figure 9. Percentage of respondents highly annoyed as a function of exposure to general transportation noise (day-night average sound level in dBA Ldn). Least squares quadratic fit to 453 data points of 27 epidemiological community surveys. The third-order polynomial fitting function of 161 of the data points by Schultz (1978) is also shown (double line). (From Fidell, Barber, & Schultz, 1991).