Many organisms use sound to communicate with others of their own species, to find a mate and to deter predators. Grasshoppers, crickets and katydids, all in the insect order Orthoptera, are among those that produce species-specific sounds, and scientists use these sounds to identify one species from another.
Daniel Otte, PhD, the Academy’s emeritus senior curator of entomology, is a leading expert on Orthoptera communication, having described and named over 1,850 species, including nearly 25% of the world’s 5,000-plus cricket species. He was one of the pioneers who recognized the species-specific nature of cricket songs, amassing over 200 field recordings of grasshoppers and crickets between the 1960s and 1990s from his field work in Africa, Hawaii and the American West. Using the technology of the day, Otte stored his recordings on reel-to-reel and cassette tapes, which unfortunately today are obsolete and deteriorating.
But now these valuable recordings are being rescued, thanks to generous funding from the Institute of Museums and Library Services and the Entomology Department’s Ted Cohn Endowment, and through a partnership with Drexel’s Westphal College of Media Arts & Design. The analog tapes are being transferred to digital media to safeguard the recordings and to allow them to be made widely available to researchers and the public.
As part of this Otteo Sound Project, students in Drexel’s co-op program are hired to digitize the recordings, database the corresponding specimens from the Orthoptera collection, and aid in adding the species audio clips to the web database Orthopnet.
Meet the author
I’m Mikayla Traini, and I am the first co-op hired to work on the project! I began in April 2022 for a six-month position, and my official title is sound engineer and entomology curatorial assistant. I did not have any experience in sound engineering before I started this co-op, though I do have a background in music performance with Drexel’s University Chorus and Chamber Singers. I am a BS/MS student in the Biodiversity, Earth, and Environmental Science Department majoring in environmental science. All my knowledge of digitizing audio has been learned on the job. These are very interesting and unique skills, and I am so happy to be part of this project!
When not working in the Entomology Collection, my time is spent in the Sound Archives studio under the supervision of Toby Seay, professor of Recording Arts and Music Production in Drexel’s Music Industry program and project director of Drexel’s Audio Archives, which includes the legendary Sigma Sound Studios collection. Professor Seay’s vast knowledge of audio engineering techniques, audio preservation, the studio’s reel-to-reel tape machines, digitization equipment, and Pro Tools music software has guided my journey through the digitization of Dr. Otte’s grasshopper and cricket tape recordings.
While Sigma Sound musicians used guitars, keyboards, drums and horns to create their sound, some Orthopterans use stridulation, or the rubbing of two body parts together to produce sound. Stridulation involves the use of a file and scraper. Grasshoppers rub their hindleg against their wing to produce sound. The file consists of a series of teeth on the inside of the hind leg, and the edge of their front wing acts as the scraper.
Crickets and katydids, on the other hand, rub their front wings together to produce sound. The scraper is formed by the edge of one of the wings, while the file consists of a series of teeth on a vein on the underside of the other wing. The scraper and file move against each other, and this friction creates the sound. Rubbing the wings across each other creates the pulses, chirps and trills; the cricket songs we hear. Think of running your thumb over the teeth of a comb.
The nitty gritty on how it’s done
So far as part of my co-op, I have accomplished two main tasks: digitizing the tape audio, and data-basing cricket specimens that are pinned or preserved in alcohol. In the audio studio, I follow a different process for the reel-to-reel tapes and the cassettes. For reel-to-reel tapes, I start by adding a length of leader to the leading edge of the tape.
The tape is then threaded onto either an Ampex or Otari tape machine for playback. While the tape is being played back, the signal is being fed through a digitizer into an Apple iMac with Pro Tools music software.
In Pro Tools, the digitized audio becomes a .wav file that can be manipulated. For the reel-to-reel tapes, the audio has been recorded in mono on the A and B sides of the tape. When the tape is rolled in through the digitizer, it records Side A forwards, and Side B is digitized at the same time but backwards. In Pro Tools, the audio can be inverted, so side B digitized backwards can now be played forwards! This saves time by avoiding having to record 30 minutes of Side A and then flipping the tape over and recording 30 minutes of Side B. Instead, they are recorded in one pass.
Cassette tapes entail a different protocol. You can only play and digitize one side at a time, so the cassettes must be physically flipped over. Cassettes are recorded in stereo, so there are two tracks, a left and right track, on each side of the tape. Pro Tools comes to the rescue again because the software interleaves the two tracks on each side turning them back into stereo.
The azimuth, the angle of the tape across the playback head, must also be adjusted to optimize the correlation between the channels. Making tiny adjustments to a screw under the playback head ensures that the audio quality of the tape matches the original recording.
Once a tape has been digitized, the object itself, whether it is a reel-to-reel tape and its box, or a cassette and its case, is photographed and scanned. These images are saved in a folder with the audio from the respective tape. Each tape is given a unique identifier; a barcode affixed to the tape. These barcodes name the folders where the audio and images of each digitized tape live.
When tapes are digitized, Dr. Otte, as the grant’s taxonomic expert, listens to each tape and identifies the species’ songs. These species song clips are added to the specimen level record in the database. The specimen level cricket data coupled with its song will be a great resource for scientists and the public!
During my co-op, I have also worked on adding over 1,700 specimens from the collection into the OrthopNet database. But that’s just a drop in the bucket. The Entomology Collection consists of some four million insects, about a third of which are Orthoptera; one of the most comprehensive collections in the world for this group.
Clearly, there is a lot more work to be done over the three years of the project. I have gained so many new skills and knowledge about insects while working under the direction of Entomology Curator and Department Chair Jon Gelhaus, PhD, and Curatorial Assistant Greg Cowper. The opportunity to work at the Academy and in the Westphal College Audio Archives has been a one-of-a-kind experience, and I am thrilled to be involved in this important project!
By Mikayla Traini, Drexel University, Biodiversity, Earth, and Environmental Science Sound Engineer and Entomology Curatorial Assistant.