Koukoulas, T; Barham, R G (2006) Transient response of the IEC 60318-1 artificial ear. NPL Report. DQL-AC 016

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Abstract

The calibration requirements for objective audiometry differ from techniques that have been established for traditional hearing testing with pure tones, in that a short duration stimulus is used typically. A calibration based on an impulse response of the ear simulator is therefore considered to be more appropriate than a steady-state response. A method of measuring the impulse response to a volume velocity input has been developed based on transforming the wideband steady-state frequency response using the inverse Fourier transform. This was adapted from a new technique for measuring the acoustical impedance of the ear simulator that has been developed separately at NPL. Calibration results of the impulse response of the IEC 60318-1 artificial ear have been obtained. Current IEC recommended practice is to characterise the transient response of the artificial ear by its steady-state response at 1 kHz. Results obtained for the impulse response have therefore been compared with the response at 1 kHz and differences in sensitivity of 14 dB have been demonstrated. This report then makes a series of recommendations on how the calibration process and IEC recommendations should be changed, with potentially significant disruption to current practices.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	DQL-AC 016
Subjects:	Acoustics Acoustics > Sound in Air
Last Modified:	02 Feb 2018 13:15
URI:	https://eprintspublications.npl.co.uk/id/eprint/3598