Phasische und tonische antworten vom tympanalorgan of Tettigonia viridissima

The reactions of the tympanal organs of the grasshopper, Tettigonia viridissima, have been investigated by recordinga ction potentials from the tympanic nerves.

The reactions are independant of the frequency of sound in the range from 1 to 100 kc/s. The organs are not capable of analysing frequencies.

The tympanal organs give phasic responses to transient components of sound of sufficient steepness (the upper and lower limits of steepness depending on incompletely understood circumstances, it could be transitory or modulations). They respond tonically to constant tones. Phasic and tonic responses are distinguised by their latencies and their activation times.

Latency of the phasic response is circa 1 ms; latency of the tonic response ca. 3.5 to 4 ms. The phasic response already appears after a single cycle of tone of 20 to 40 kc/s; the activation time of the tonic response is at least 1.25 ms (hence, at 20 kc/s, at least 25-30 cycles).

The absolute refractory period of the phasic response is 2 ms; the relative, about 12 ms. The tonic response appears in the refractory period of the two responses.

There are interactions between the two responses.

A constant tone reduces the phasic response (masking effect), but does not cause it to dissappear entirely.

The maximal modulation frequency of a tone is ca. 250 to 400 c/s. Clicks also arouse single response up to a frequency of about 400 per second.