by Carl Strang
We have no standardized language to describe singing insect sounds. Such is needed, because different people use different words to describe the same song. We’re not lacking for words, in a sense we have too many.
The oblong-winged katydid’s song has been described in several different ways, for instance.
Richard Alexander was the dean of singing insect research in the Great Lakes area before he retired from his post at the University of Michigan. Here are some of the words and phrases he used: “clear, whistle-like sound (crickets) or a ‘noise’ (buzz, click, rasp, whirr, rattle, etc.) (all groups except crickets).” Buzz, crackling, noise, rasping, lisp, “tick-buzz,” “whispery, intense buzzes,” sibilant buzz, smooth without vibrato, vibrato, whining buzz, rough buzz, trill, chirp, “tink” sound, phrase, ragged phrase, “zzzzzz-zik-zik”, seedy.
More recently, Elliott and Hershberger in their popular book on singing insects used a lot of quantitative language regarding frequency (pitch, the highness or lowness of sound), but also a lot of terms that remain undefined as far as I can see: chirp (“each chirp is actually a brief trill”), buzz, buzzy trill, note, “chirps (brief buzzes),” tick, “clicks or tsips,”, purr, clicking whirr, raspy notes, clicks or zits, shuffle, rattling, zeee-dik!, dzt!, lispy buzzing notes, swishing rattles, pulsating drone, whining drone.
In approaching this problem I like Alexander’s division of songs into two main categories, tones on the one hand (relatively clear, musical notes like those of a wind or stringed instrument, for instance a flute or a single violin note; such a sound has a very narrow frequency range) and more mechanical sounds on the other (resembling the sounds produced by percussion instruments such as rattles, drums, scrapers, clickers, or else a ticking watch; a wide range of frequencies is produced at once, so there is no single, clearly dominant tone).
Words connected to tones include: musical, chirp, trill, “tink,” note, whine, siren. Words connected to mechanical sounds include buzz, tick, click, rasp, whirr, rattle, noise, crackle, lisp, swish, and a variety of attempts to render the sounds into words (zick, zit, dzt, zee, dik, tsip, zzz). I am not sure what to do with “drone.” It usually is applied to cicada songs, some of which are more tone-like (canicularis) and some of which are more mechanical (linnei). Perhaps a drone is a third, somewhat intermediate category, with pulses that are too rapid to distinguish but each of which has a broad frequency range (I am not speaking of vibrato here, but the individual vibrations that make up the droning sound). The song of Roesel’s katydid qualifies as a drone, under this definition.
For the moment, I think there are six primary terms needed in describing insect songs. Each of these can be further qualified with descriptors.
A note is a separate, musical tone that can be very short (Allard’s or tinkling ground cricket), or long and continuous (four-spotted or black-horned tree cricket). Descriptors can specify the pitch, length, volume and tonal quality of the sound. Sonograph analysis reveals that a note is composed of pulses, but these usually are too rapid to be discerned by ear (though some of those tree cricket songs acquire a wavering quality at low temperatures).
A trill is a rapidly and evenly pulsing sound (the pulses slow enough to be discerned) that has a tone quality. The pulses seem connected, rather than having pauses, however brief, between them. A trill can be brief (jumping bush cricket) or extended (Say’s trig). A trill can be qualified in the same way as a note, with the addition of pulse rapidity, and pauses or interruptions that occur in some species.
A chirp is a brief bundle of rapid, irregular notes (spring and fall field crickets produce the most familiar example). Irregularity in the spacing, volume and/or length of the element notes separates a chirp from a trill. Chirps tend to be relatively brief.
A drone is the mechanical analog of a note, but I can think of no brief examples (the striped ground cricket and two-spotted tree cricket are possibilities, though I am more inclined to think of these as buzzes). The pulses or vibrations are too rapid to discern, though there may be vibrato. Examples include extended cicada songs like those of the dog day or Linne’s cicada, Carolina ground cricket, and Roesel’s katydid. Descriptors include volume, length, nature and abruptness of beginnings and endings, vibrato (which can be more legato or more staccato in its attack), pitch range, whether there is a rise and fall in pitch, and tonal quality.
A buzz is the mechanical analog of a trill, and like a trill its length can be short (the elements of a common true katydid song), intermediate (as in most meadow katydids) or extended (as in the rattler round-winged katydid). Here the descriptors include volume, length, abruptness of beginnings and endings, pitch range or center, pulse rate, and sound quality (e.g., rasping, lisping, rattling).
A tick is the briefest of mechanical sounds. Examples are found in the typical song of the greater angle-wing, and the series of brief sounds leading into the buzz of many meadow katydids. Volume, number, and, when they are produced in series, descriptions of the spacing and rapidity of ticks, help describe them.
A perfect system may not be possible. Not only do we have an excess of vocabulary, we also know that different people hear the same song differently, and so will use different words to describe it. I would greatly appreciate help with this, so please comment on what needs clarification or to express points of disagreement.