The optimized chirp stimulus

  BMCHIRP generates optimized Chirp described in Dau et al. (2000)

	sig = bmchirp(f1,f2,fs,len,flat)
	generates the ``approximated'' optimized chirp developed by Dau et al.
	(2000). This chirp compensates for travel-time differences along the
	cochlear partition. The equations were derived on the basis of a linear
	cochlea model (de Boer, 1980).

	A vector sig is returned. The vector is filled with zeros to match the
	length of len. If len equals zero the minimum length for the chirp will
	be calculated.

	f1  : lower (start) frequency of the chirp (in Hz)
	f2  : upper (stop) frequncy of the chirp (in Hz)
	fs  : sampling frequency in Hz (standard: 25000 Hz)
	len : length of the chirp in s (standard: 0 s)
	flat: flat spectrum (1) or not (0) (standard: 0)
	sig : the resulting chirp (output)

	This script is based upon the article by
	T. Dau, O. Wegner, V. Mellert and B. Kollmeier (2000): "Auditory
	brainstem response with optimized chirp signals compensating
	basilar-membrane dispersion." J Acoust Soc Am 107(3): 1530-1540.

	Derivation of traveling wave velocity:
	E de Boer (1980): "Auditory physics. Physical principles in hearing
	theory I", Phys Rep (62), 87-174.

	Cochlear frequency-position function:
	DD Greenwood (1990): "A cochlear frequency-position function for
	several species -- 29 years later", J Acoust Soc Am (87), 2592-2605.

 (c) O. Wegner, T. Dau 09/96


1.8 fixed a really small normalization bug with the flat-option (thanks to Helmut Riedel)
1.7 fixed a bug that occurs with the options len~=0 and flat=1
1.6 now with an additional switch for the flat spectrum chirp
1.5 internal release
1.4 only some minor changes in documentation etc.
1.3 first official release


Matlab-function to generate the optimized chirp stimulus: bmchirp.m

Journal articles related to the chirp stimulus:

Torsten Dau, Oliver Wegner, Volker Mellert and Birger Kollmeier (2000):
Auditory brainstem response with optimized chirp signals compensating basilar-membrane dispersion.
J Acoust Soc Am 107(3): 1530-1540.
Full Text: [ PDF (179 kB) - ZIPped PS (161 kB) ]

Stefan Uppenkamp, Sandra Fobel, and Roy D. Patterson (2001):
The effects of temporal asymmetry on the detection and perception of short chirps.
Hear Research 158(1-2): 71-83.

Oliver Wegner, and Torsten Dau (2002):
Frequency specificity of chirp-evoked auditory brainstem responses
J Acoust Soc Am 111(3): 1318-1329.
Full Text: [ PDF (437 kB) - ZIPped PS (430 kB) ]


Oliver Wegner and Torsten Dau
AG Medizinische Physik
Carl von Ossietzky-Universität Oldenburg
D-26111 Oldenburg


Last Update: 2002 Mrz 05
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