Purdue Audiology researcher works to better understand harmonies in our heads, ears

Malinda McPherson, a new assistant professor in the Purdue University Department of Speech, Language, and Hearing Sciences, conducts research on the harmonious qualities of Tsimané music in Bolivia.

Written by: Tim Brouk, tbrouk@purdue.edu

Malinda McPherson

Malinda McPherson had harmony in her head when she first picked up a viola at age 8 and has helped guide her through her academic research.

As a Speech and Hearing Bioscience and Technology PhD candidate at Harvard University and a postdoctoral associate at the University of California, San Diego, McPherson published numerous studies on how humans perceive harmonic sounds and their pitch. McPherson was hired in fall 2022 as a new Purdue University Department of Speech, Language, and Hearing Sciences (SLHS) assistant professor but is currently finishing her postdoctoral work before her West Lafayette arrival in August.

A member of Forbes’ 2022 “30 Under 30” list in science, McPherson analyzes how people differentiate and remember harmonic sounds. Speech and other musical sounds have harmonic structure, or pitch, as words go up and down in frequency. McPherson’s work can inform how people hear harmonic sounds and what can be done by hearing aid developers to help those with hearing loss better receive those important harmonic tones from the voices of family and friends or from their favorite piece of music. The research can be utilized to understand how humans with hearing loss navigate not just music but also conversation in crowded restaurants and gatherings.

While conducting this research, McPherson performed in symphonies and chamber music groups, winning awards for her talents along the way. These days, playing the viola is mostly a stress reliever and creative outlet, but her musical activities continue to provide inspiration for her research.

“I’ve always been interested in sound. I think part of my love of playing viola has translated into a desire to understand how we hear complex sounds,” she said. “I find the process of how we perceive sound fascinating, and I think a lot of that fascination does derive from my early experiences learning to play a musical instrument and working hard to make sound in a particular way.”

Another aspect of McPherson’s research involves understanding music perception among indigenous communities. The groups she studies create music that does not follow the rules that most Western music follows. She visited Bolivia to study the Tsimané people’s music and how they appreciate and listen to musical harmony and other sounds.

What has drawn you into the field of hearing research?

I was initially drawn to study hearing because of my background as a musician, but one of the many reasons I’ve stayed in this field is because of the people who work in this area. Hearing research has traditionally been a smaller field, particularly compared to research in other sensory domains like vision, so is it is quite collegial and collaborative. That is reflected in the department at Purdue. Hearing also has an underappreciated impact on well-being, and I’m excited the SLHS department at Purdue has such a public face regarding why it’s important to protect your hearing and why hearing research is critical for general health.

You taught a class called Sound and Music and Perception in San Diego. How does music get woven into your work?

I started my course with a discussion of “What is music?” How do we define it? The class agreed that there aren’t very good definitions that encompass all that music is and can be. Therefore, in my class and in my research, I have to teach and study the elements that make up many musical systems around the world. One of these building blocks is pitch — how high or how low our sounds are and how those sounds are structured over time.

I’ve been interested in understanding how we perceive pitch both in speech and in music. In speech, the difference between a question and a statement is due largely to pitch — whether you have a rising inflection or a flat inflection. In music, pitch gives us melody and harmony. I’ve been studying how we perceive these complex signals and found that people seem to have multiple complimentary systems for processing pitch. Which system you use depends on the context. Several of my experiments examining basic pitch perception have been informed by my background as a musician.

How has the fieldwork in Bolivia affected your research?

I feel honored to have worked with Tsimané communities in Bolivia and to have been invited back year after year. It’s an incredible opportunity to question our assumptions about auditory perception and about experimental design. When conducting cross-cultural research, it is important to think critically about how we set up experimental tasks and how we translate questions and instructions between languages so everybody can understand the task in the same way.

We’ve been studying the Tsimané’s pitch perception and how it differs from individuals in the U.S. I have been curious about whether the wildly different musical and auditory diets between U.S. and Tsimané participants can cause the two groups to perceive sound differently or prefer different types of sounds. My fieldwork has motivated me to explore the diversity of auditory perception worldwide.

What are you looking forward to about starting at Purdue this fall?

I look forward to translating my science into the clinic. I am hoping that some of my findings could either be used for early diagnostic tests for various forms of hearing loss or could be used to improve processing in devices like cochlear implants or hearing aids. If we understand the signals the auditory system is using to extract information from the world, then perhaps we can optimize our devices to extract that information and give people the best chance at hearing important sounds. That’s the ultimate aim of my work.