Phonetics researcher Rebekka Puderbaugh on auditory illusions and takeaways from her first festival performance
This summer I performed in the Cabaret of Dangerous Ideas (CoDI) at the Edinburgh Festival Fringe. My show was titled “Don’t believe your ears!” and in it, I presented a number of auditory illusions. While most people are familiar with the idea of optical illusions, auditory illusions are less familiar. In my show, I first introduced the idea of illusions with visual examples, then showed parallel examples with sound. Unlike optical illusions, auditory illusions can be hard to identify without other people around to report on what they hear. Having the audience all listening to the same sound and talking to each other about it was a great opportunity to discuss the range of things people can hear in the exact same sound and why we might not all hear the same thing.
Describing sounds in obscure languages
In my own research, I use acoustics to describe sounds in under-documented languages. Acoustic measurements can tell us how long or loud a sound is, or what frequency it is oscillating at. However, since human speech is complex and varied we still have to rely on human judgment to sort various speech sounds into linguistically meaningful categories. Research on speech and auditory perception shows that many factors can contribute to whether humans interpret speech sounds as either the same or different from other speech sounds. This could mean that sounds that share acoustic properties are interpreted as different by listeners, or that sounds which are acoustically distinct are interpreted as the same.
Listeners are subjective
We do not yet fully understand the mechanisms that humans use to determine whether a sound is the same or different but we do know that several factors probably play a role, such as the language background and experience of the listener, and the phonetic and linguistic context a sound occurs in. This knowledge, though incomplete, highlights the subjectivity of listener identification of speech. It demonstrates a need for careful documentation that is independent of human perception.
Although there are no real “tricks” involved (and I don’t always know how different people will perceive the sounds!), the show did have a feeling of magic to it because of the illusions. Linguistics is sometimes portrayed as an exercise in making unseen patterns visible, or in this case audible. At one point I even used one of the CoDI organisers as a live puppet to demonstrate that speech perception is not just something that happens in your ears. Your eyes and other sensory organs may also contribute!
Embedding time for discussion
A big part of the CoDI format is engagement and discussion with the audience. Although I have been teaching for several years and am comfortable speaking in front of a large crowd, leaving time for discussion has always been more difficult for me. Luckily, CoDI audiences are eager and engaged, and their questions were insightful and interesting to talk about. As a result, I am now incorporating more active discussion into my lectures during term time.
Festival of Physics performance
I’ll be performing “Don’t believe your ears!” again at the Festival of Physics at 8.30pm on 26 October 2019 at Dynamic Earth, as part of a special show with CoDI.
About Rebekka Puderbaugh
Rebekka Puderbaugh is a Teaching Fellow in Phonetics at the University of Edinburgh. Her research focuses on acoustic aspects of speech sound, particularly the phonetic description of understudied languages.