Gap detection in the European starling (Sturnus vulgaris). III: Processing in the peripheral auditory system.

Abstract

Gap-detection thresholds were determined for
single units in the cochlear ganglion and in auditory
nerve fibres of the starling from responses to two broadband
noise bursts separated by a temporal gap of between
0.4 and 204.8 ms. All 35 units showed a threshold
within the range of gap sizes tested. The median minimum-
detectable gap was 12.8 ms with the minimum being
1.6 ms. A multiple regression analysis revealed that
the size of the minimum-detectable gap was not significantly
correlated with the neuron's CF, with its sharpness
of tuning as given by its bandwidth 10 dB above
threshold, or with its QIOdB value. Only the level of stimulation
above the neuron's threshold showed a significant negative correlation with the size of the minimumdetectable gap. These results are discussed with respect to theoretical considerations of limits posed on temporal resolution by the characteristics of peripheral filters. These findings are also discussed in the context of the coding of gaps at different levels of the starling's auditory system and in relation to psychoacoustic results in the starling on gap detection and time resolution described by temporal modulation transfer functions.