Article,
Practical Ranges of Loudness Levels of Various Types of Environmental Noise, Including Traffic Noise, Aircraft Noise, and Industrial Noise
International journal of environmental research and public health, (2011)
Abstract
In environmental noise control one commonly employs the A-weighted
sound level as an approximate measure of the effect of noise on people.
A measure that is more closely related to direct human perception
of noise is the loudness level. At constant A-weighted sound level,
the loudness level of a noise signal varies considerably with the
shape of the frequency spectrum of the noise signal. In particular
the bandwidth of the spectrum has a large effect on the loudness
level, due to the effect of critical bands in the human hearing system.
The low-frequency content of the spectrum also has an effect on the
loudness level. In this note the relation between loudness level
and A-weighted sound level is analyzed for various environmental
noise spectra, including spectra of traffic noise, aircraft noise,
and industrial noise. From loudness levels calculated for these environmental
noise spectra, diagrams are constructed that show the relation between
loudness level, A-weighted sound level, and shape of the spectrum.
The diagrams show that the upper limits of the loudness level for
broadband environmental noise spectra are about 20 to 40 phon higher
than the lower limits for narrowband spectra, which correspond to
the loudness levels of pure tones. The diagrams are useful for assessing
limitations and potential improvements of environmental noise control
methods and policy based on A-weighted sound levels.
