This document specifies two methods for estimating the loudness and loudness level of sounds as
perceived by otologically normal persons under specific listening conditions. The first method is
intended for stationary sounds and the second method for arbitrary non-stationary (time-varying)
sounds, including stationary sounds as a special case.
The methods can be applied to any sound recorded as single-channel measurements using a microphone,
or as multi-channel measurements, for example by means of a head and torso simulator (see Annex D).
Since most important technical sounds are time-varying, a model of time-varying loudness is preferable.
The methods are based on the Zwicker algorithm.[14] The method for stationary sounds is provided for
reasons of continuity and also offers the use of measured one-third-octave-band levels as input. The
more general method for arbitrary sounds calculates the specific loudness pattern based on measured
time signals by applying a signal processing model that is directly related to physiological and
psychological characteristics of the human hearing system. Loudness is calculated from the specific
loudness pattern. It has been shown that this method provides a good match to the results of many
loudness experiments using synthetic and technical sounds.
No prior knowledge about the properties of the sound (e.g. broadband or narrowband noise, tonal
content) and no user interactions are required for the fully automated application of the method.
The evaluation of the harmful effect of sound events is outside the scope of this document.