Transposed tones vs Gaussian impulses G. Christopher Stecker Dept of Speech & Hearing Sciences University of Washington
Background: stimuli for envelope ITD at high frequency –Sinusoidal amplitude modulation –Effects of modulation frequency, duration (Nuetzel & Hafter 1976) –Filtered impulse trains Independent manipulation of overall bandwidth and rate of modulation Analog Filtered Impulses: Hafter & Dye 1983, Hafter et al Digital Gaussian Impulses: Buell & Hafter 1988, Hafter & Buell 1990, Saberi 1996, Stecker & Hafter 2002 –Transposed tones Proper comparison (given peripheral models) to low-freq tones van de Par & Kohlrausch 1997, Bernstein & Trahiotis 2002, Griffin et al
SAM TT GI
SAM TT GI
SAM TT GI
SAM TT GI
SAM TT GI
SAM TT GI
SAM TT GI
SAM TT GI
SAM TT GI
SAM TT GI
Comparing signals Show figures
Comparing signals Show figures Differences: –GI has 2 parameters for bandwidth, rate –TT / SAM have 1 parameter for modulation rate –GI & TT have “off periods” and steeper slopes not found in SAM
Some data SAM (Bernstein & Trahiotis 2002) TT (Bernstein & Trahiotis 2002) GI (Buell & Hafter 1988) AI (Hafter et al 1990) AI (Hafter & Dye 1983)
Same data GI (Buell & Hafter 1988) AI (Hafter et al 1990) AI (Hafter & Dye 1983) SAM (Bernstein & Trahiotis 2002) TT (Bernstein & Trahiotis 2002)
Questions / Issues What are the important features of impulsive envelopes (for effective ITD)? Do rate limitation and binaural adaptation relate to one another? Onset vs Ongoing cues differ b/w studies. –What counts as “onset”?
Future developments? GI trains –Arbitrary timing –Dynamic parameters Transposed stimuli –Extend to many LF modulators (e.g. noise) Study of duration / rate / bandwidth?
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