This field recording was made one early evening in the northern suburbs of Melbourne. The greengrocer [cyclochila australasiae] is a common cicada that has successfully adapted to the suburbs of both Melbourne and Sydney on the south eastern seaboard of Australia. The calls produce a natural enveloping soundscape throughout the city streets during the hotter months. The song they sing is a continuous, loud call that can reach 120 decibels, the pain threshold for human hearing. Through a process of digitally ‘stretching' the insect's song, the tempo is slowed, the pitch lowered and the frequency reduced. This reveals the pulsing mechanical construction of the sound, and is common practice as a form of species identification. The deep rhythmic bass highlights the nature of sound as a physical vibration - we can feel the sound through its resonance in our bodies as much as through our hearing capacity.

Visually, the imaging consists of the decorative architectural element of the frieze. A frieze is a pattern which repeats in one horizontal direction. It is an ancient form of decoration which occurs in most cultures throughout the world. This form of patterning draws a certain correlation with the oscillogram – the visual aspect of sound files on digital audio software programmes. This visual addition to the ephemeral nature of sound has enabled great development in the understanding of the sonic world of animals.

The template for the image is a detail from a photograph by Peter Lillywhite, Manager of the Entomology Collection, Museum Victoria, of a greengrocer in the museum's collection. The image describes the point where the cicada's wing meets its body, close to the tymbal organs - the sound producing organs.

Notes on the Greengrocer [Cyclochila Australasiae] from MS Mould's comprehensive ‘Australian Cicadas'

Observations suggest that the life cycle of most Australian cicadas is at least 2 years in length, with the greengrocer's life span being 6-7 years. The length of adult life varies between two and four weeks [p.8].

Cicadas are known for their loud songs and have developed the most effective means of doing so of all insects [p.21]. The tymbal organs are the organs of sound production. They consist of a pair of ribbed membranes on either side of the abdomen, which, when buckled inwards and then relaxed, produce a sharp pulse of sound [p.22]. These rapid rhythmic pulses combine to form the basis of the song. The amplification of this pulsing is achieved via a resonating air sac within the large and spacious abdominal area. In the greengrocer the tymbals buckle alternately and thus produce a particularly high number of sound pulses per second [p.25].

It is the male cicadas which produce the songs with which we are familiar, although there are two species where females produce songs [p.21]. Cicadas have to reach a certain body temperature before singing commences, hence their seasonal occurrence. For the greengrocer this temperature is 18.5'C [p.21]. Some species, including the greengrocer, tend to group together to increase the total volume [p.22]. The group then sings in chorus, and the fragmented part of the song [which is the build up to the continuous phase, or full song] is synchronized [p.63].

Cicadas produce a number of songs which vary according to function, the most common one being the calling song, a mating song to attract females [pp.21-22]. Other songs include a distress song - a broken, erratic noise - and a courtship song, which is a quiet call after a female has been attracted. The greengrocer also has a dying song - a series of clicks - which occurs during the last few hours of life.

Reference

Moulds, MS.1990 Australian Cicadas NSW University Press, Sydney