U-M exposure scientist Dr Rick Neitzel, who leads the Apple Hearing Study, spoke with Radio New Zealand about the research.
The partnership between the University of Michigan and Apple is undertaking research which involves up to 180,000 people regularly reporting on the noise around them.
Neitzel told Radio New Zealand that one of the features of humans becoming increasingly urbanised was that people were now encountering noise almost every hour of every day.
Exposure Research Lab 