Alma Schrage is a recent graduate of UC Berkeley and a research assistant in the Bowie lab in the Museum of Vertebrate Zoology. Over several years I have watched her become an ornithologist. In this interview she discusses her research on bird song and how it has been affected—or not—by being partially deaf.
Why study bird song?
It’s interesting on several different levels. If you’re interested in cognition and behavior, bird song provides so many different things to study. You can also study how vocalizations tie in with genetics, morphology and such to help provide a fuller picture of the bird, or you can study the factors that drive development of bird song such as different acoustic environments, and selective forces on calls and songs.
How can you do research on bird song if you’re partially deaf?
You may be surprised to know, but bird song analysis is actually really visual and has been long before I started doing research. Bird song researchers use computer programs such as Raven or Audacity that convert the recorded sound to visuals that measure time and frequency/pitch (spectrograms) and time and volume (waveforms) – this makes it much easier to quantify different aspects of songs and calls such as frequency, number of syllables, the slope of the change in pitches, volume, etc. So the analysis is heavily visual and quantitative.
I enjoy spotting unusual songs. An example from my research is an Oak Titmouse whose song had a bitonal first note – that’s really unusual for Oak Titmice, so it was interesting.
How well can you hear bird song?
Very badly. I was born deaf and with hearing aids I can hear the human voice and loud low pitched bird sounds. Without hearing aids, 95-120 decibels (think someone yelling loudly or a jackhammer) sounds like a whisper. I’m completely deaf at the high frequencies of typical human hearing.
In the field, if a vocalization is 5500 Hz or higher, I usually can’t hear it. I don’t have much sound sensitivity or discrimination – a visual equivalent would be near-sightness. People or things close to me I can understand passably well, but the further away or quieter a sound is, it becomes “blurry” – I can’t pick it out of the surrounding sound, which is noticeable but incomprehensible.
I also have tinnitus in the high frequencies, which further complicates listening for birds. Tinnitus is brain-generated noise and is common with progressive hearing loss. Ironically, it often sounds like the dawn chorus – however, if the sound continues even after I turn off my hearing aids momentarily, I know it’s the tinnitus. So if I find myself hearing a bird singing with a high frequency, I am very skeptical.
In the field, I can usually notice and sometimes recognize lower pitched birds by sound – crows, jays, owls, and doves if they’re loud enough, but it’s not something I consider reliable when I’m making an identification. Warblers, bushtits, titmice, and flycatchers I know from experience I don’t hear – I’ve seen the songs real time on a spectrogram in the field, but their songs are either too quiet or too high for me to hear.
How do you use technology to supplement your ears when you’re listening to birds in the field?
I use an app on my phone that creates real time spectrograms – this allows me to identify diffferent species in the field by visualizing the sounds. Just to be clear, this is not the kind of app that “listens” for you and then makes an identification for you – although there are some apps like that out there, but in terms of reliability they’re not really there yet. And as a researcher, I want to understand the structure of the songs themselves and the sounds of the ecosystem in which they take place, not just what species is singing them. I collect spectrograms of bird recordings of different species and memorize how they look – sort of like memorizing a field guide, except with vocalizations.
This was supplemented by the great teachers and GSIs I had when I took IB 104: Natural History of the Vertebrates here at UC Berkeley. They would point out the sounds of various species to the class on field trips, and I always brought the spectrogram app along, so I was able to get a lot of practice identifying songs in the field. It was very gratifying whenever I was able to make a correct identification based on vocalizations.
Obviously it’s not perfect. Since it’s a visual app, it’s not easy to watch for bird songs and to watch for the birds themselves at the same time. Believe me, I’ve tried! But if I ever get my hands on Google Glass, I know what I’ll be testing out first. And regardless of whether you’re observing songs in an auditory or visual mode, there are some things that make listening harder, like if there’s a lot of noise.
But there are some advantages as well – it’s very easy to take a picture of the spectrogram, so it’s handy to have whenever I’m caught without recording gear, expecially when I’m in a new place where I’m not familiar with the songs of the local species. If I see a vocalization I can’t identify, I just snap a picture to look it up later. It’s also really nice for listening to the dawn chorus – if several birds are singing at the exact same time but at different frequencies – it shows up very clearly on a spectrogram and is easy to distinguish.
The specific app I use is called Spectrogram and was programed for iOS by Pete Schwamb.
As for regular recording equipment, in the past I’ve used a Marantz recorder with a Sennheiser shotgun mic, but this spring I’m going to be trying out an Olympus-12 recorder (the pro is that it’s smaller and con is also that it’s smaller) with a Sennheiser shotgun mic, so we’ll see how that goes.
How did you get interested in birds and bird research?
The ultimate cause was that I’ve been interested in birds for as long as I can remember. More generally I was interested in everything to do with animals and nature.
The proximate cause was a grant – at the end of junior year of college I was fortunate enough to be admitted to the Biology Fellows Program. I had taken Ornithology with Rauri Bowie that spring and was working for credit in curatorial and the preparations lab with Carla Cicero at the Museum of Vertebrate Zoology, and I was hoping to do some sort of research with birds. It turned out Carla was looking for a research assistant for a song study of sibling species in the Baeolophus genus. So I spent the summer going through dozens of recordings and analyzing thousands of songs. I continued the project through the next year and summer and got to present the work at a conference last fall.
What is your favorite bird song?
Favorite bird song to listen to: Common Loon (Gavia immer, ML 107964). Click here to listen.
Favorite bird song to look at: Warbling Vireo (Vireo gilvus, ML144024). Click here to listen.
Thanks so much for letting me interview you, Alma! Look for Alma’s research on titmouse song to be published sometime soon.