The sound we can see: working with hearing loss in the field

When I was 19 I went for a checkup with an audiologist and found out that I was hearing only 90% of what I should be. The doctor said that for my age, this was a high level of hearing loss, and attributed it possibly to the intense course of antibiotics I took for kidney failure when I was one year old. He suggested that I come back yearly to repeat the hearing exam, to verify if my ability further decreased below my current hearing levels. Of course I ignored this advice and never went back. When I started my graduate studies six years later, I decided it was finally time to visit the audiologist again, because I discovered that I could not hear the species of frog I had decided to base my research on. This was a very scary moment for me. How did I find myself in this situation?

In the last year of my undergraduate studies I took an ecology course and fell in love with the topic. I knew I wanted to earn a master’s degree in ecology, ideally working with animal populations. In Brazil, one has to take a standardized exam to enter a graduate program. I traveled 440 km to take the test and passed; I began my studies in the Federal University of Paraná located in Curitiba, in the south of Brazil. Among all the available mentors, there was one who carried out research on ecological dynamics of insects and anuran amphibians. I chose his lab and wrote a project proposal examining the population dynamics of an endemic species of stream frog (Hylodes heyeri) in the Atlantic Forest in Brazil, specifically Pico do Marumbi State Park, Piraquara, in the state of Paraná. Much of what I was to be doing was completely new to me: I had never worked with frogs and I also had never practiced the mark-and-recapture method. I thus faced a steep learning curve and had to learn a LOT about lab and fieldwork from my team and my mentor. In my first field outing, during which I was to learn how to identify and capture the species I would study, I discovered that I could not hear the frog. A labmate who accompanied me to the field said, “Are you listening? The frog is so close to us.” He thought I was not hearing the frog due to lack of experience, or because of the background noise of the stream. I worried that something else was amiss, and this finally prompted me to go back to my audiologist. There, I discovered that I had lost 2% more of my hearing, and this loss compromised treble sounds, those in the range of high to very high frequencies, precisely overlapping my frog’s vocalizations.

Now, I’m a PhD student and I use hearing aids programmed specifically for my hearing loss, which primarily encompasses frequencies above 4000 Hz. I was initially ashamed to wear hearing aids because people mocked them. But I didn’t consider changing projects, because I knew I could get help localizing the frog. I also knew there would be ways for me to analyze the sound without necessarily hearing it. Even with hearing aids, however, I can only hear the call of my frog when I am no more than 4 meters away. Other members of my lab can detect the sound of the frog from much farther away, even when they are 20 meters or more from the stream. This means that for every survey I carry out in the field, I need a person to accompany me to guide me to the frog, using their sense of hearing to identify the sound. But the assistance I receive in the field goes beyond locating my frog; the field can be dangerous for many reasons: I may not hear dangerous animals—such as puma, collared peccary, or leopards—approaching; and I may lose track of my team if people call me from too far away. Even for scientists without hearing loss, it is advisable not to carry out fieldwork alone.

In recent years, I have had the opportunity to learn Brazilian sign language (LIBRAS) in graduate courses. I am happy that it is a requirement for my degree! When I am in the field I communicate primarily with gestures. I am lucky that my frogs are diurnal, because I am able to see my companions in the field, making communication much easier. Once my companion hears the frog, they look at me so I can read their lips or we make gestures so as to not scare the frogs. Sometimes I use headphones, point the microphone of my recorder in the general direction of the frog, and increase the volume to better understand where the sound comes from—this trick of using my main research tool (my recorder) to find my frogs was taught to me by a friend who also carried out research in bioacoustics and had the challenge of finding a tiny mountain frog species that hid in leaf-litter (thank you, André Confetti). My frogs are also tiny, only 4 cm long. They camouflage in the streams and spook very easily, but in order to obtain my data, I need to get as close as 50 cm from the frog. Only then can I really start. The aim of my work is to analyze the effect of anthropogenic noise (such as traffic road sounds transmitted by playback) on frog communication. Once I am in position, I can play the anthropogenic sound, and record the frog’s call. I take these recordings back to the lab and experience the most rewarding aspect of my efforts to find these frogs. The recordings are transformed into graphs of the frequency and length of each call. Although I cannot hear the sounds my frog makes, I can see them! After seeing the sound I can analyze several call variables and calculate various statistics.

Would I recommend field work such as mine to somebody who finds themselves in my predicament? If you are open to creative workarounds, such fieldwork is possible for all. Having a field companion, using signs to communicate, and making use of the amplification provided by my recording equipment has solved the majority of my problems. Most important of all, having support from your mentor and other people who can help and you can trust is crucial. I do not intend to continue with bioacoustics research after I graduate, but if I need to mentor any students in the area, I’ll be happy to do it. I worry about my hearing loss too, in thinking of how it will affect my teaching in the future, because sometimes I hear words incorrectly and confuse their meaning. But I recently exposed my hearing loss in an interview; reading more at The Mind Hears and on other blogs has inspired me to worry less about my hearing loss and to continue to forge ahead in my career.

Biography: My name is Michelle Micarelli Struett and I am a doctoral candidate in the Graduate Program in Ecology and Conservation (where I also received my MS) at the Federal University of Paraná in Curitiba, Paraná, Brazil. My undergraduate was at Maringá State University in Maringá, which is also in Paraná. I am interested in animal behavior, especially in frogs, and in my research will examine multi-modal communication in the Brazilian Torrent Frog (Hylodes heyeri). This unique frog can sing from one or both sides of its mouth (it has two vocal sacs), depending on context. I will attempt to determine what that context is that stimulates those two possibilities (auditive, visual, or tactile), and how anthropogenic noise may interfere with communication and social interactions in this frog. Despite my hearing loss (which primarily encompasses frequencies above 4000 Hz), I have not been constrained from working with frog calls and bioacoustics.