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- During stridulation in the gomphocerine grasshopper Omocestus
- viridulus the leg movements, sound pattern and either summed auditory
- nerve activity or single interneuron activity were recorded.
- Simultaneous laser interferometric and vibrometric measurements of the
- displacement and velocity of the tympanic membrane were performed at
- the pyriform vesicle (d-receptor group). Slow displacements of the
- tympanic membrane occur in phase with the ventilatory and stridulatory
- rhythm and reach 10 mu m(peak-peak) and 1-3 mu m(peak-peak) in
- amplitude, respectively. Additionally, the tympanic membrane
- oscillates maximally in the range 5-10 kHz. These high-frequency
- oscillations are due to sound production and motor activity and
- correspond in amplitude to oscillations evoked by sound pressures of
- 90-dB SPL. They activate the auditory receptors during most of the
- stridulatory cycle even during mute stridulation. Only at the lower
- reversal point of the leg movement are membrane vibrations and
- receptor activity at a minimum. As a consequence the response of
- receptors and interneurons to auditory stimuli are generally impaired
- and an auditory response of receptors and interneurons can be elicited
- only during a short period at the lower reversal point. Although in
- this phase of the stridulatory cycle auditory sensitivity is present,
- males do not show phonotactic responses towards female songs during
- ongoing own stridulation.
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