Apple’s Hearing and Audio Technologies team published a paper in the Journal of Acoustical Society of America this month outlining some of the key data points from Apple’s Hearing Study.
The nationwide Apple Hearing Study, launched using the Apple research app in November 2019 (Apple Inc., Cupertino, CA), is characterizing the levels at which participants listen to headphone audio content, as well as their listening habits.
Apple Hearing study participants have shared nearly 300,000,000 ( that’s 300 million!!) hours of sound level measurements and over 200,000 hearing assessments.
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Apple’s Hearing Study details
Researchers have previously measured personal exposures to environmental sound or measured or estimated headphone audio on samples ranging from hundreds to thousands of participants.
However, the Apple Hearing Study may be the first study to measure both types of sound exposure simultaneously and longitudinally over a multiyear period on a large sample of participants and combine those measures with multiple types of repeated hearing assessments.
The new paper ‘Toward a better understanding of nonoccupational sound exposures and associated health impacts: Methods of the Apple Hearing Study’ was published on March 4th, 2022.
This new paper describes the methods of the study, which collects data from several types of hearing tests and uses the Apple Watch noise app to measure environmental sound levels and cardiovascular metrics. The paper provides a good overview of the data collection methods and some of the important facets of the study.
One of the salient features of this study is that its analyses will promote understanding of the overall exposures to sound and associated impacts on hearing as well as cardiovascular health.
Beyond the headphone sound levels, the Apple Watch does a fantastic job in capturing environmental sound.
Apple Watch and Environmental Sound Monitoring
Environmental sound levels are measured using the noise app, available on Apple Watch Series 4 and later, and can be shared with the study by participants if they choose to do so.
Environmental sound levels can be viewed in real-time by participants using the noise app on their Apple Watch; exposure summaries are available in the health app on the iPhone.
Sound level measurements are automatically suspended while the Apple Watch speaker is being used, e.g., while taking a phone call or interacting with Siri, and when the water-lock feature on the Apple Watch is manually initiated (e.g., when swimming).
Similar to headphone audio levels, the environmental sound level trends and statistics can be viewed in the health app.
The noise app includes a notification feature with a default threshold of 90 dBA. When this threshold is exceeded, a notification to the participant is triggered.
The Apple Watch heart rate metrics can be used as a marker for cardiac status and a signal related to the physical and psychological stresses on an individual (Singh et al., 2018, Acharya et al 2006).
Studies have also shown the effect of noise exposure on cardiovascular metrics ( Kraus et al 2013 and Burns et al 2016).
It will be interesting to see how Apple researchers incorporate some of the insights and learning from this study in an effort to promote better cardiovascular health.
Although there are some limitations to the study as outlined in the paper, this large effort is expected to produce meaningful insights that will be valuable moving forward both for Apple and the general research community at large.
After all, it was Tim Cook who famously remarked “ If you zoom out into the future and you look back, and you ask the question, “What was Apple’s greatest contribution to mankind?’ It will be about health’.
