THE AUDITORY MODELING TOOLBOX

Applies to version: 0.9.9

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ABSOLUTETHRESHOLD - Absolute threshold at specified frequencies

Usage

t=absolutethreshold(freq);
t=absolutethreshold(freq,...);

absolutethreshold(freq) will return the absolute threshold of hearing in dB SPL at the frequencies given in freq. The output will have the same shape as the input.

[outvals,table]=absolutethreshold(...) additionally returns the frequencies table defining the choosen standard. The first column of the table contains frequencies in Hz, and the second column contains the absolute threshold at the given frequency.

absolutethreshold takes the following optional parameters:

'iso226_2003' Free field binaural as given by the ISO 226:2003 standard.
'iso389_2005' Diffuse field binaural as given by the ISO 389-7:2005 standard.
'map' The ISO 226:2003 standard coverted to minimal audible pressure using the method from Bentler & Pavlovic 1989.
'er3a' Using ER-3A insert earphones. This is described in the ISO 389-2:1994(E) standard
'er2a' Using ER-2A insert earphones. This is described in Han & Poulsen (1998)
'hda200' Using HDA200 circumaural earphone. This is decribed in the ISO 389-8:2004 standard.

Absolute thresholds for the ER2A and HDA-200 are provided up to 16 kHz by the ISO 389-5:2006 standard.

The default is to use the 'iso226_2003' setting.

References:

R. A. Bentler and C. V. Pavlovic. Transfer Functions and Correction Factors used in Hearing Aid Evaluation and Research. Ear and Hearing, 10:58-63, 1989.

L. Han and T. Poulsen. Equivalent threshold sound pressure levels for Sennheiser HDA 200 earphone and Etymotic Research ER-2 insert earphone in the frequency range 125 Hz to 16 kHz. Scandinavian Audiology, 27(2):105-112, 1998.

ISO 226:2003. Acoustics - Normal equal-loudness-level contours. International Organization for Standardization, Geneva, Switzerland, 2003.

ISO 389-2:1994(E). Acoustics - Reference zero for the calibration of audiometric equipment - Part 2: Reference equivalent threshold sound pressure levels for pure tones and insert earphones. International Organization for Standardization, Geneva, Switzerland, 1994.

ISO 389-5:2006. Acoustics - Reference zero for the calibration of audiometric equipment - Part 5: Reference equivalent threshold sound pressure levels for pure tones in the frequency range 8 kHz to 16 kHz. International Organization for Standardization, Geneva, Switzerland, 2006.

ISO 389-8:2004. Acoustics - Reference zero for the calibration of audiometric equipment - Part 8: Reference equivalent threshold sound pressure levels for pure tones and circumaural earphones. International Organization for Standardization, Geneva, Switzerland, 2004.

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