Mechanical phase shifters for coherent acoustic radiation in the stridulating wings of crickets: the plectrum mechanism

Abstract

SUMMARYMale crickets produce stridulatory songs using engaged tegmina (forewings): a plectrum on the left sweeps along a tooth row on the right. During stridulation, the plectrum moves across the teeth and vibrations are amplified by the surrounding cells and veins, resonating at the frequency of tooth impacts. The advance of the plectrum on the file is controlled by an escapement mechanism so that passing each single tooth generates one wave of a highly tonal signal. Both tegmina must oscillate in phase to avoid destructive interference. But as each plectrum-tooth contact begins, the right and left tegmina react in opposite oscillatory directions. A mechanical phase shifter is part of the left tegmen and compensates to achieve wing oscillation synchrony. We use a new technique to simulate plectrum-on-file interactions: in combination with laser vibrometry, this technique assessed plectrum mechanics in the cricket Gryllus bimaculatus. Using an excised teneral file, shaped like a partial gear and moved by a motor, and a microscan Doppler laser vibrometer, plectrum and left-tegmen mechanics were explored. The results show that plectrum and harp oscillate with a phase difference of ca. 156 deg., a shift rather than a complete phase inversion (180 deg.). This phase shift occurs at the site of a large wing vein (possibly A3). Plectrum and harp vibrate with similar fundamental frequency, therefore, plectrum torsion resonant frequency is important for maintaining vibration coherence. The mechanical aspects involved in this partial phase inversion are discussed with respect to the escapement mechanism. The plectrum mechanics and its implications in katydid stridulation are also considered. Supplementary material available online at

Systematics and Acoustics of North AmericanAnaxipha(Gryllidae: Trigonidiinae)

“…Synchronization of forewing oscillations and file tooth impacts.-How insects as small as crickets can produce sounds that are nearly pure in frequency has long been of interest and talented researchers have studied the problem using increasingly sophisticated physical and electronic methods (e.g., nocke 1971, Sismondo 1979, koch et al 1988, Bennet-Clark 1999, Bennet-Clark & Bailey 2002, Montealegre-Z et al 2009, Mhatre et al 2012, robillard et al 2013. Most of these authors relied on crickets that are easily reared or otherwise conveniently available for laboratory studies and few were concerned with the effects of temperatures on the frequencies produced.…”

Changing resonator geometry to boost sound power decouples size and song frequency in a small insect

“…During stridulation, the wings of crickets, when set in motion by the action of the stridulatory apparatus, vibrate and produce pressure variations in the surrounding medium effectively producing sound (3). Sound radiation using wings has been studied in many groups in the singing Orthopteran insects: bush crickets (30), crickets (27,28,32) and tree crickets (23). In most crickets, only part of the wing (the harp or the mirrors) moves significantly and radiates sound at the song CF (27,30,32).…”

“…Sound radiation using wings has been studied in many groups in the singing Orthopteran insects: bush crickets (30), crickets (27,28,32) and tree crickets (23). In most crickets, only part of the wing (the harp or the mirrors) moves significantly and radiates sound at the song CF (27,30,32). Unusually, in O. henryi the entire wing (the harp, and the three distal wing mirrors) shows significant vibrational behavior (Fig.…”

“…Except for the anal field (A), all areas of the wing respond with nearly equal displacement amplitudes between 2.5 and 4.5 kHz (Fig. 5) unlike in field crickets wings in which the harps contribute the most to the frequency response (28,32). The phase response of the transfer function begins near 90°at about 2.5 kHz and falls to near −90°at about 5 kHz (Fig.…”

Spatial evolution of friction of a textured wafer surface

“…* Corresponding author: Hong LIANG. E-mail: hliang@tamu.edu and pre-patterned with parallel nickel [15] and silicon dioxide (SiO 2 ) stripes. The width of the Ni strips is in the range of 70-88 μm while that of SiO 2 strips is in the range of 200-300 μm.…”