  We present the first wireless earbud hardware that can perform hearing
screening by detecting otoacoustic emissions. The conventional wisdom has been
that detecting otoacoustic emissions, which are the faint sounds generated by
the cochlea, requires sensitive and expensive acoustic hardware. Thus, medical
devices for hearing screening cost thousands of dollars and are inaccessible in
low and middle income countries. We show that by designing wireless earbuds
using low-cost acoustic hardware and combining them with wireless sensing
algorithms, we can reliably identify otoacoustic emissions and perform hearing
screening. Our algorithms combine frequency modulated chirps with wideband
pulses emitted from a low-cost speaker to reliably separate otoacoustic
emissions from in-ear reflections and echoes. We conducted a clinical study
with 50 ears across two healthcare sites. Our study shows that the low-cost
earbuds detect hearing loss with 100% sensitivity and 89.7% specificity, which
is comparable to the performance of a $8000 medical device. By developing
low-cost and open-source wearable technology, our work may help address global
health inequities in hearing screening by democratizing these medical devices.
