Erica Walker

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Tell us about yourself.

I am an environmental exposure scientist and epidemiologist currently working at Boston University’s School of Public Health as a postdoctoral researcher under the mentorship of Dr. Jon Levy. I am primarily interested in understanding the relationship between sound exposure and health but feel that we need take a step back and think more deeply about how we characterize sound and noise exposure.


What sparked your interest in measuring and understanding noise?

I was a working artist and my studio was in my home, which was a basement apartment. My previous neighbors left and in moved this family with two small kids. These kids would run the length of their apartment (which was my ceiling) nonstop and it drove me insane. Over a period of a few months, I noticed that my mental and physical health took a sharp decline. I began to document the issue by measuring the sound levels and recording the time the events happened. It was my desire to take them to court and/or getting them evicted. In my lease, I found a statement about “Quiet Enjoyment” and set out to see if I could make a legal argument around this. Surprisingly (or not) this wasn’t an easy task and while researching this, I realized a few key things. First, I was far from alone. There are LOTS of people grappling with noise issues. Second, there are very few options available to alleviate the issue. Third, the prevailing attitude is that noise is a mere nuisance and not a serious environmental stressor impacting our health. This makes it difficult to get people to care.


When did Noise and the City come into being, and how has the work progressed since you’ve started?


Noise and the City ( came into being as I began my field work for my dissertation as a doctoral student at the Harvard T.H. Chan School of Public Health. Not only did I collect sound measurements around Greater Boston, I had also released The Greater Boston Neighborhood Noise Survey, a survey designed to gather a better understanding about community noise perception. From the beginning, it was very important to me to both inform and engage the communities I was operating in and Noise and the City was the platform of choice.


Do you have a most noteworthy finding or interesting result from your research thus far?

My dissertation was two-fold. First, I wanted to establish a biological rational for considering other aspects of community sound that are often ignored—in particular a sound’s frequency composition. I worked with Dr. Jenn Cavallari of UCONN HEALTH and conducted an experiment examining the effects of low and high frequency sound on acute measures of stress and cardiovascular responses. We found that low frequency sound in particular brought about acute declines in HRV during exposure. This study gave me the greenlight to proceed to my next goal. Second, I wanted to develop new models and metrics that better characterize sound exposure. From the World Health Organization to local governance we tend to only define sound by how loud it is and do so using an A-weighted decibel.

Briefly, A-weighting is a type of weighting that gives preference to the sounds we process through the auditory system. Sounds across frequencies we typically don’t process through the auditory system (low frequency sounds in particular) are discounted.  However, sound is a very complex physical exposure and is so much more than loudness. I was particularly interested in a sound’s frequency composition and wanted to figure out the distribution and determinants of infrasound and low frequency sound in Greater Boston. If you have ever experienced these particular types of sound (think rumbling bus or heavy footsteps from your upstairs neighbor) you know that loudness is only half of the story. Conducting my research in Greater Boston allowed me to see that in poorer neighborhoods these low frequencies are quite dominant, which brings into question the relevance of using loudness only sound metrics. We also fail to capture the human experience—we can only seriously talk about noise, which is defined as unwanted sound, when we get input from the community.


You’ve created some really fascinating maps out of this work. Can you share one with us?


These maps were created by the super talented Dr. Marcos Luna of Salem State University. I really like maps detailing the difference between Unweighted and A-weighted sound levels. You can clearly see areas in the city where defining sound using the A-weighting system may be extremely problematic. I also like the maps detailing noise perception from aircraft noise. I think that these two maps give us insight into how we can better define and display community noise issues.


What’s next for Noise and the City?

While I was very happy to release the Greater Boston Noise Report in late 2016 ( (I can’t believe it has been 2 years), I knew that as soon as I hit the “publish” button and the website went live that the snapshot we provided the community could only tell a static story. This was very disconcerting as noise is a very dynamic exposure.  After finishing up at Harvard, I was awarded a small grant from The Radcliffe Institute for Advanced Study. The funds from this grant were used to develop NoiseScore—a smartphone app that allows you to objectively and subjectively document a noise event and visualize your response (and the response of others) in real time ( I would like to work to continue to improve this app and continue to more deeply define community noise in ways that are relevant, informative, and accessible. This, unfortunately requires funding so in addition to dreaming about next steps, I am in the process of writing grants to continue our work.


Where can we go to learn more?, and (for in-depth case studies, sound clips and podcasts from real-life Boston residents—including Dr. Luna!)

Published On: August 30, 2018