Cycloptiloides canariensis (Bolívar, 1914)

Temporal pattern
A trill sounds like a faint buzzing that increases in volume and ends abruptly (maximum intensity 30 dB SPL at 1 m). The trill is composed of a train of pulses (syllables) produced at a uniform rate but continuously increasing in amplitude (Fig. 2).
The intervals between successive trills are variable. According to the general principle of cricket stridulation, every pulse is produced by the interaction between the file and plectrum during a single closing of the wings. The wingstroke rate therefore determines the pulse rate, whereas the tooth-strike rate, in interaction with the vibration of the sound radiator, determines the carrier frequency (Bennet-Clark, 1989). At 27  ̊C, trill durations of 2.1±0.3 s (mean ± S.D.) were measured (8 individuals, 10 trills each). Each trill was composed of 261±39 pulses, which gives a mean pulse rate of 124 pulses s 1 (mean pulse period 8 ms). The pulse duration (pd), the number of cycles of the carrier frequency per pulse and the pulse amplitude (pa) increase continuously during a trill (pd from about 1 to 7 ms; number of cycles from about 9 to 30; pa, 10 dB rise ratio). Carrier frequency (see below) and pulse period (pp) remain constant.

Carrier frequency
The file-and-plectrum mechanism and tuned sound radiator (see below) emit tone pulses of a nearly pure frequency. Because of its predominant character, the fundamental frequency can easily be calculated by counting the cycles from an oscillogram (film speed 8ms 1). For five animals, every successive tenth pulse within a trill (recorded at 27 ̊C) was analysed in this way. The pulses may differ in amplitude (Fig. 2A) but their frequency does not. Nevertheless, each individual had its own characteristic frequency within the range 5.7±0.1kHz (N=25 pulses) to 6.1±0.2kHz (N=27 pulses). [1]

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