Role of probe tone parameters in frequency selectivity for normal listeners.

The objective of this research was a determination of the role of probe tone parameters in frequency selectivity. Frequency selectivity is the ability of the auditory system to analyze a complex sound into its frequency components, and is typically evaluated by measuring the psychophysical tuning curve. Generally this entails documenting the effect of varying the center frequency of a narrowband noise masker for a given pure tone probe, 10 dB above threshold. In the present study, a new approach was taken. A family of tuning curves were generated for a series of tone probes which differed in frequency, duration and intensity, but which remained constant in energy. The results for three normal-hearing subjects indicated that the critical parameter for the shape of the tuning curve was the energy of the probe. Decreasing the energy below values generally tested resulted in aberrant shapes across subjects, which bore some resemblance to those documented in hearing-impaired listeners. Temporal summation was suggested as the unifying principle.