Smartphone-bundled earphones may double as low-cost hearing aids

Certain commercial wireless earphones used with smartphones compare favourably with conventional hearing aids and thus have the potential to be repurposed as assistive listening devices in individuals with mild-to-moderate hearing impairment, as reported in a study from Taiwan.

In an electroacoustic test, a pair of smartphone-bundled earphones (AirPods Pro) met four out of five standards for personal sound amplification products (PSAPs). PSAPs are a category of wearable electronic devices intended for individuals with normal hearing but have been shown to help compensate for hearing loss in terms of listening effort and speech-in-noise perception among patients with mild-to-moderate hearing loss. [iScience 2022;doi:10.1016/j.isci.2022.105436; JAMA Otolaryngol Head Neck Surg 2019;145:516-522; JAMA 2017;318:89-90]

AirPods Pro had the frequency response smoothness and bandwidth, total harmonic distortion, and maximum output sound pressure level at 90 dB. The only exception was that the earphones had an equivalent internal noise that exceeded the standard regulated, which means that the device may impact speech perception among users.

AirPods Pro vs hearing aids

The performance of Airpods Pro was further evaluated in 21 adults (mean age 42.9 years, 57.14 percent women) with bilateral symmetric mild-to-moderate sensorineural hearing loss (SNHL) and no prior experience with hearing aids. The device was then compared to its predecessor, Airpods 2, and one pair each of premium and basic hearing aids.

During the test, the participants were asked to repeat verbatim a short sentence read by the authors in the following conditions: without any assistive listening device, as well as while wearing AirPods Pro, AirPods 2, a premium hearing aid, and a standard hearing aid.

AirPods Pro did as good as basic hearing aids but were slightly inferior to premium hearing aids when used in a quiet environment; AirPods 2 had the lowest performance among the four devices, although the device helped the participants hear more clearly than when not wearing hearing aids.

In a noisy environment, on the other hand, AirPods Pro delivered similar performance to premium hearing aids when the noises moved in a sideways direction. However, the wireless earphones failed to improve hearing when the noises came from the front.

“Two reasons may account for the difference between the two scenarios,” noted Ying-Hui Lai, the study's co-author and a bioengineer at National Yang Ming Chiao Tung University in Taipei.

“It may relate to the trajectories soundwaves travel with, as well as the advanced signal processing algorithm by premium hearing aids. This finding will hopefully inspire engineers to design hearing aids and PSAPs that are more sensitive in certain directions,” Lai said, adding that the noise-cancelling feature of AirPods Pro gave it an advantage over AirPods 2.

Cheaper and more accessible

“To our knowledge, this study is the first to use smartphone-bundled earphones as the tested PSAPs to compare hearing performance among patients with symmetrical mild-to-moderate hearing loss. We found that AirPods Pro met most of the electroacoustic criteria and may be considered a competent PSAP,” according to the authors.

In 2016, Apple released "Live Listen," a feature that allows its wireless earphones AirPods to be used for sound amplification and, subsequently, to function like a PSAP.

“Globally, the wireless earphone market is growing rapidly. Some companies are interested in exploring the possibility of designing earbuds with sound amplification features. Our study proves that the idea is plausible,” Lai said.

Lai and colleagues see AirPods Pro as a potential hearing assistance device for adults with mild-to-moderate hearing loss. These wireless earbuds can be an adequate alternative to hearing aids, with the added benefit of being cheaper.

The cost of hearing aids bears most of the blame for the low uptake of such devices. At USD 3,000 to 6,000 per pair, hearing aids are expensive enough to keep many people from correcting their hearing problems. In comparison, AirPods Pro just costs USD 249. [Am J Med 2016;129:245-250; Disabil Rehabil 2021;43:436-446]

A previous report has found that about three-fourths of individuals with hearing loss do not use hearing aids. This number is worrying, according to the study authors, because hearing problems will eventually get in the way of effective communication, leading to a lower quality of life and subsequent increased healthcare expenses, if left unaddressed. [Arch Intern Med 2012;172:292-293]

Dr Yen-fu Cheng, the study's corresponding author and an otolaryngologist at Taipei Veterans General Hospital, acknowledged that it can be difficult to convince patients to use hearing aids.

“These wireless earbuds are of course not perfect, but they would be a good starting point for many patients who don't have access to professional hearing aids. They will see an increase in quality of life even with these earbuds,” Cheng said.