A new standard for measuring loudness - Moore
Submitting InstitutionUniversity of Cambridge
Unit of AssessmentPsychology, Psychiatry and Neuroscience
Summary Impact TypePolitical
Research Subject Area(s)
Medical and Health Sciences: Neurosciences
Psychology and Cognitive Sciences: Psychology
Summary of the impact
Loudness is the subjective magnitude of a sound as perceived by human
listeners and it plays an important role in many human activities. It is
determined jointly by the physical characteristics of a sound and by
characteristics of the human auditory system. A model for predicting the
loudness of sounds from their physical spectra was developed in the
laboratory of Professor Brian Moore with support from an MRC programme
The model formed the basis for an American National Standard and is
currently being prepared for adoption as a standard by the International
Organization for Standardisation (ISO). In addition, the model has been
widely used in industry worldwide for prediction of the loudness of
sounds, for example: noise from heating, ventilation and air-conditioning;
inside and outside cars, and from aircraft; and from domestic appliances
The auditory perception group is led by Professor Brian Moore (Department of
Psychology from 1977; Professor of Auditory Perception from 1995). In the
late 1990s, Moore and colleagues (Brian Glasberg and Thomas Baer, each
Senior Research Associate) started developing a model in humans for
predicting the loudness of sounds based on their physical spectra. This
model was based on extensive prior research into human frequency
selectivity, which had produced a detailed characterization of human
`auditory filters' and how these vary with frequency and level.
The initial version of the model,1 published in 1996 was an
extension of the earlier `Zwicker loudness model' (1958), which had until
that point been used in many practical acoustical applications. The
extension accounted more accurately for the shapes of equal-loudness
contours (showing the sound level required for equal loudness of pure
tones with different frequencies) and the way that equal-loudness contours
change with loudness level, as published in the literature. The model also
accurately predicted loudness judgements for a variety of sounds, as
obtained in Moore's laboratory and documented in the published literature.
In 1997, the model was further altered, developed and refined2(the
most highly cited paper in the Journal of the Audio Engineering
Society) and, as a result, became substantially different from the
Zwicker model. This version enabled prediction not only of the loudness of
sounds, but also of the loudness of a given sound in the presence of
background noise. This paper included equal-loudness contours predicted by
the model, which differed from the equal-loudness contours that were
currently the accepted standard. However, in 2003 a new ISO standard for
equal-loudness contours was published, based on new perceptual data
collected independently of Moore's group; and these new contours were
close to those predicted by the model. During the period 1998-2002, data
were gathered on the loudness of time-varying sounds, by Moore's group and
by researchers working independently; together, these were used to develop
a version of the model that could deal with time-varying sounds.
In 2006, Moore's model was further modified to allow accurate prediction
of the detection thresholds of both simple and complex sounds,3
and in 2007 it was extended to enable accurate predictions of loudness
under conditions where the sound is different in the two ears, as is
common in everyday life.4 Moore's model is the only one to
include this feature.
In parallel with research on the perception and modelling of loudness for
normal hearing, Moore and colleagues have extended the model to predict
loudness as perceived by hearing-impaired people5 (the most
highly cited paper in the journal Auditory Neuroscience), based on
data gathered in Moore's laboratory and by other groups. This version of
the model has been used by Moore's group to develop methods for fitting
hearing aids with multi-channel compression,6 which compensate
for the effect of loudness recruitment commonly found in people with
sensorineural hearing loss.
References to the research
1. Moore, B. C. J., and Glasberg, B. R. (1996). "A revision of
Zwicker's loudness model," Acustica — Acta Acustica 82, 335-345.
2. Moore, B. C. J., Glasberg, B. R., and Baer, T. (1997). "A model
for the prediction of thresholds, loudness and partial loudness," J. Audio
Eng. Soc. 45, 224-240.
3. Glasberg, B. R., and Moore, B. C. J. (2006). "Prediction of
absolute thresholds and equal- loudness contours using a modified loudness
model," J. Acoust. Soc. Am. 120, 585-588.
4. Moore, B. C. J., and Glasberg, B. R. (2007). "Modeling binaural
loudness," J. Acoust. Soc. Am. 121, 1604-1612.
5. Moore, B. C. J., and Glasberg, B. R. (1997). "A model of
loudness perception applied to cochlear hearing loss," Auditory Neurosci.
6. Moore, B. C. J., Glasberg, B. R., and Stone, M. A. (2010).
"Development of a new method for deriving initial fittings for hearing
aids with multi-channel compression: CAMEQ2-HF," Int. J. Audiol. 49,
DETAILS OF MRC programme grants (all with Moore as principal
1993-1998 Studies of impaired hearing and development and evaluation of
signal processing hearing aids. £534870
1998-2003 Studies of normal and impaired hearing and development of
digital hearing aids. £1,189,563
2003-2008 Studies of normal and impaired hearing and development and
evaluation of signal processing hearing aids. £1,510,000.
2008-2013 Psychoacoustics of normal and impaired hearing and applications
to hearing aid design and fitting. £2,067,098.
Details of the impact
The version of the model published by Moore's group for normal hearing
was implemented in 2007 in American National Standards Institute (ANSI)
standard number ANSI S3.4-2007.1 As a result, the model is used
by companies based in the USA and elsewhere for evaluating the loudness of
their products. The model is widely used in industry for prediction of the
loudness of everyday sounds such as noise from aircraft, traffic, inside
cars, heating and ventilation systems, wind turbines, and many other
situations. It has also been used by government organisations.2
The Danish company Bruel and Kjaer3 (a leading manufacturer of sound and
vibration measurement equipment) uses the model as part of package of
sound-measuring equipment that is widely used in industrial applications.
A range of companies, including Boeing,4 Bose,5 Samsung,6 and Nissan7 use
the model, as implemented in a computer program, to assess the loudness of
their products, since it eliminates the need to undertake expensive and
time-consuming tests with human listeners. The executable code of the
model for the loudness of stationary sounds is made available as part of
the ANSI S3.4-2007 standard. Companies pay a license fee to use the
software for the model of loudness for time-varying sounds. Examples of
1) The model has been used by the US Department of Transportation2 and by
Nissan7 in developing the design and specification of warning
sounds to be emitted by quiet cars, such as electric automobiles.
2) The model has been used by Boeing Corporation, a major manufacturer of
aircraft, to evaluate the loudness of sounds both inside and outside of
3) The model has been used by Bose Corporation, a major manufacturer of
audio systems for domestic and professional applications in developing a
variety of products.5
4) The model has been used by Samsung7 in a variety of applications
including development of more efficient perceptual coders (improvements to
MP3) and evaluation of the loudness of mobile telephones.
5) The version of the model applicable to hearing-impaired people has
been used by Moore's group to develop methods for fitting hearing aids
with multi-channel compression (essentially all modern hearing aids
incorporate such compression). A recent extension to these methods
(reference 6 in section 3) can be used to fit recently introduced hearing
aids with an extended high- frequency response (i.e. those that amplify
for frequencies up to 8-10 kHz as opposed to the limit of 4-5 kHz that is
common for hearing aids). This method, called CAM2, is currently being
used in clinical trials with a novel form of hearing aid with extended
high-frequency response, called the `Earlens'. The trials are being
conducted in Stanford, USA, with Moore as advisor. The CAM2 method is
currently being licensed by Cambridge Enterprise.8
The model is being adapted as the basis for a new ISO standard. Voting on
the proposed standard should take place later on this year. The new
standard will be published in parallel with a revised version of a
standard based on the older (and less accurate) Zwicker model for a
Sources to corroborate the impact
- The ANSI standard explicitly includes a statement that it is based on
the Moore/Glasberg loudness model:
ANSI, 2007. ANSI S3.4-2007. Procedure for the computation of loudness of
steady sounds, American National Standards Institute, New York.
- Hastings, A., Pollard, J. K., Garay-Vega, L., Stearns, M. D., &
Guthy, C. (2011, October). Quieter Cars and the Safety of Blind
Pedestrians, Phase 2: Development of Potential Specifications for
Vehicle Countermeasure Sounds. (Report No. DOT HS 811 496).
Washington, DC: National Highway Traffic Safety Administration.
This document describes use of the Moore/Glasberg loudness model in
developing the specifications for quiet vehicles. This document has been
uploaded to the repository. It can be accessed at:
Supporting documents in the repository have been provided by:
- Research Engineer at Bruel and Kjaer (Denmark), a leading manufacturer
of equipment for acoustical measurements and calibration.
- Manager, Acoustics Technology, Noise, Vibration and Emissions
Engineering, Boeing Corporation, a major aircraft manufacturer.
- Manager, Acoustic Research, Bose Corporation (U.S.A.), a leading
manufacturer of loudspeakers and sound systems.
- Manager, Market Quality Engineering, Nissan Corporation, a major
manufacturer of motor vehicles, including electric cars.
- Principal Engineer, Digital Media & Communication R&D Center,
Samsung Electronics, a major manufacturer of mobile telephones,
electronic equipment, and appliances.
- A web site describing the CAM2 software and its uses and licensing