ABSTRACT
Many bush crickets (Tettigoniidae) produce calls that consist of trains of transient high-frequency pulses (Fig. 1). Each pulse is generated by a file tooth on one wing being struck by a plectrum on the other, causing the wing resonator to produce harmonic transients each composed of only two or three cycles of oscillation. In animals, high-frequency sound can only be detected by means of some form of auditory filter, since the refractory period of the nervous system restricts direct measurement using periodicity to frequencies below 1 kHz. The necessity of using a filter produces a paradoxical situation with these brief transients. If the bandwidth of a tuned filter is such that frequency can be accurately discriminated, the response time may exceed the duration of the signal and then there would be no output. To respond to such a signal, the filter bandwidth must be increased but then frequency information is lost.
