Noise Criteria and Noise Regulations

Using some of the noise measures and descriptors discussed and surveys and human response studies, various criteria have been proposed so that noise environments can be determined that are acceptable for people, for speech communication, for different uses of buildings, for sleep, and for different land uses. In some countries such criteria are used to write noise regulations for new machinery, vehicles, traffic noise, railroad noise, aircraft and airport noise, community noise, and land use and planning. It is beyond the scope of this book to give a comprehensive summary of all these criteria and regulations. Instead just a few are described in this section. The interested reader is referred to the literature [29, 32, 66] for more complete summaries of criteria, regulations, and legislation.

6.16.1 Noise Criteria

An example of noise criteria is given in Table 6.4, which is based on those suggested by Beranek and Ver [17] and gives recommended NCB curve values (and approximate A‐weighted levels) for various indoor functional activity areas. The NCB curves are given in Figure 6.10. For example, the air‐conditioning unit chosen to supply air to bedrooms (used in residences, apartments, hotels, hospitals, etc.) should have a spectrum corresponding to no more than an NCB curve of 25–40 (or an A‐weighted SPL of no more than about 38–48 dB).

Table 6.4 Recommended values of NCB curves for different uses of spaces in buildings^a.

Source: Based in part on Ref. [17].

Type of Space (and Acoustical Requirements)	NCB Curve	Approximate LA
Broadcast and recording studios	10	18
Concert halls, opera houses, and recital halls	10–15	18–23
Large auditoriums, large drama theaters, and large churches	<20	28
Broadcast, television, and recording studios	<25	33
Small auditoriums, small theaters, small churches, music rehearsal rooms, large meeting and conference rooms	<30	38
Bedrooms, sleeping quarters, hospitals, residences, apartments, hotels, motels, etc.	25–40	38–48
Private or semiprivate offices, small conference rooms, classrooms, and libraries	30–40	38–48
Living rooms and drawing rooms in dwellings	30–40	38–48
Large offices, reception areas, retail shops and stores, cafeterias, and restaurants	35–45	43–53
Lobbies, laboratory work spaces, drafting and engineering rooms, general secretarial areas	40–50	48–58
Light maintenance shops, industrial plant control, rooms, office and computer equipment rooms, kitchens, and laundries	45–55	53–63
Shops, garages, etc. (for just acceptable speech and telephone communication)	50–60	58–68
For work spaces where speech or telephone communication is not required, but where there must be no risk of hearing damage	55–70	63–78

^a Also given are the approximate equivalent A‐weighted sound pressure levels L_A.

Another example of noise criteria are the guidelines recommended by EPA [31], WHO [68], FICON [33], and various European road traffic regulating bodies. See Table 6.5. As already mentioned, L_eq is very widely used to evaluate road traffic, railroad, and even aircraft noise [36]. Interestingly, railroad noise has been found to be less annoying than traffic noise in several surveys [29, 72, 73]. This has resulted in noise limits (using L_eq) that are 5 dB lower for railroad noise than road traffic noise in Austria, Denmark, Germany, and Switzerland and 3 dB lower in The Netherlands [29]. Gottlob terms this difference the “railway bonus.” [29] An example of national noise exposure criteria is the guidance given in the British government guidelines adopted in 1994 for land development. See Table 6.6. This table shows guidelines in A‐weighted SPLs, L_eq, for four noise exposure categories [74]. The noise exposure categories can be interpreted as follows: [75] (A) Noise need not be considered as a determining factor in granting planning permission, although the noise level at the high end of the category should not be regarded as a desirable level; (B) noise should be taken into account when determining planning applications, and, where appropriate, conditions should be imposed to ensure an adequate level of protection against noise; (C) planning permission should not normally be granted; where it is considered that permission should be given, for example because there are no alternative quieter sites available, conditions should be imposed to ensure a commensurate level of protection against noise; and (D) planning permission should normally be refused [76, 77].

Table 6.5 Guidelines from EPA [31], WHO [68], FICON [33], and various European agencies [29] for acceptable noise levels.

Source: Based in part on Ref. [32].

Authority	Specified A‐Weighted Sound Pressure Levels	Criterion
EPA levels	Ldn ≤ 55 dB (outdoors)	Protection of public health and welfare with adequate margin of safety
Document [31]	Ldn ≤ 45 dB (indoors)
WHO	Leq ≤ 50/55 dB (outdoors; day)	Recommended guideline values
Document (1995) [68]	Leq ≤ 45 dB (outdoors; night)
	Leq ≤ 30 dB (bedroom)
	Lmax ≤ 45 dB (bedroom)	Considered generally compatible with residential development
U.S. Interagency Committee (FICON) [33]	Ldn ≤ 65 dB
	65 ≤ Ldn ≤70 dB	Residential use discouraged
Various European road traffic regulations [29]	Leq ≥ 65 or 70 dB (day)	Remedial measures required

Table 6.6 Guidelines used in the United Kingdom for A‐weighted equivalent sound pressure levels for different noise exposures categories.

Source: Based on Ref. [74].

		Noise Exposure Category
Noise Source		A	B	C	D
Road traffic	(07:00–23:00)	<55	55–63	63–72	>72
	(23:00–07:00)	<45	45–57	57–66	>66
Rail traffic	(07:00–23:00)	<55	55–66	66–74	>74
	(23:00–07:00)	<45	45–59	59–66	>66
Air traffic	(07:00–23:00)	<57	57–66	66–72	>72
	(23:00–07:00)	<48	48–57	57–66	> 66
Mixed sources	(07:00–23:00)	<55	55–63	63–72	>72
	(23:00–07:00)	<45	45–57	57–66	>66