1Department of Radioelectronics, Czech Technical University in Prague, Czech Republic
Broadband noise with a sharp falling edge in the power spectrum evokes a monaural noise edge pitch. When comparing with the pitch of a matching pure tone, the same pitch sensation is evoked for pure tone shifted slightly into the spectral region of the noise. In the frequency region between 100 Hz and 2.5 kHz, the pure tone frequency is about 2% to 9% below the noise edge frequency for lowpass filtered noise and about 2% to 20% above the noise edge frequency for highpass filtered noise [Hartmann et al. (2019) J. Acoust. Soc. Am. 145:1993-2008]. The departure from the edge frequency grows as the edge approaches low frequencies. The noise edge pitch can be explained by temporal theories calculating autocorrelation or by a place theory employing lateral inhibition. It is shown here that the noise edge pitch can be also derived from the first order intervals between successive peaks in the temporal fine structure of the noise filtered with a gammatone filterbank. The filterbank was composed of 300 filters distributed between 20 Hz and 10 kHz according to the Cam scale. Histogram of the first-order interpeak intervals reveals a hump centered around the noise edge pitch frequency. The hump is more visually apparent for LP noise than for HP noise as the edge frequency approaches low frequencies (below about 200 Hz), which corroborates experimental results in literature. At 200 Hz, ratio between the pitch frequency estimated as the mid of the hump and the edge frequency is about 1.1, which agrees with literature. These results support temporal theories of pitch perception employing first-order interspike intervals [Huang and Rinzel (2016) Front. Comput. Nerosci. 10:57(1-17)].
Acknowledgements: Supported by an internal grant at the Czech Technical University in Prague SGS20/180/OHK3/3T/13.