ABSTRACT
A compound stimulus consists of a combination of nine individual Gaussian-shaped tone pulses, each tone pulse covering a well defined and restricted area in the frequency-time domain. All nine individual tone pulses have the same masked threshold (in pink noise). The masked threshold of the compound stimulus is measured as a function of the configuration of the nine tone pulses in the frequency-time domain. Each configuration fits within a restricted frequency-time window of 500–3170 Hz along the frequency scale and 100 ms along the time scale, and the nine individual tone pulses are always well separated in frequency and/or time. Various of such configurations are considered, including the case of perfect spectral synchrony: nine tone pulses with different carrier frequencies and coinciding peaks of the Gaussian envelopes. Of all configurations considered, the latter appears to lead to optimal detectability. The effect of spectral synchrony on signal detection amounts to about 5 dB, and appears to be restricted to very brief signals only.
