The Robinson–Dadson curves are one of many sets of

equal-loudness contours An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon and ...

for the

human ear In vertebrates, an ear is the organ that enables hearing and (in mammals) body balance using the vestibular system. In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear cons ...

, determined experimentally by D. W. Robinson and R. S. Dadson. Until recently, it was common to see the term Fletcher–Munson used to refer to equal-loudness contours generally, even though the re-determination carried out by Robinson and Dadson in 1956, became the basis for an ISO standard ISO 226 which was only revised recently. It is now better to use the term

as the generic term, especially as a recent survey by ISO redefined the curves in a new standard, ISO 226:2003. According to the

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

report, the Robinson-Dadson results were the odd one out, differing more from the current standard than did the Fletcher–Munson curves. It comments that it is fortunate that the 40-Phon Fletcher-Munson curve on which the

A-weighting A-weighting is a form of frequency weighting and the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. A-weighti ...

standard was based turns out to have been in good agreement with modern determinations. The article also comments on the large differences apparent in the low-frequency region, which remain unexplained. Possible explanations are: * The equipment used was not properly calibrated. * The criteria used for judging equal loudness (which is tricky) differed. * Different races actually vary greatly in this respect (possible, and most recent determinations were by the Japanese). * Subjects were not properly rested for days in advance or were exposed to loud noise in travelling to the tests which tensed the tensor timpani and stapedius muscles controlling low-frequency mechanical coupling.

References

External links

ISO StandardFletcher–Munson is not Robinson–Dadson
* ttp://www.phys.unsw.edu.au/~jw/hearing.html Hearing curves and on-line hearing testbr>Equal-loudness contours by Robinson and Dadson
{{DEFAULTSORT:Robinson-Dadson curves Acoustics Hearing Audio engineering Sound Psychoacoustics

See also

References

External links