Noise-canceling headphones: Potential risks behind convenience

Our brains decode hundreds of sounds every day. Many people choose to wear noise-canceling headphones to reduce noise interference. Noise-canceling headphones, through active or passive noise cancellation technology, can effectively block out external noise, providing users with a quiet auditory environment. However, this convenience may hide some potential hearing health risks.

According to a recent BBC report, Sophie, a 25-year-old administrative assistant in London, found herself struggling to distinguish the source of sounds in noisy environments while attending university in London. She was frequently told she was "unfocused," "daydreaming," or "a bit dazed." Although hearing tests showed her hearing was normal, further examination led to a diagnosis of auditory processing disorder (APD). APD is a neurodevelopmental problem characterized by difficulty distinguishing the source of sounds or understanding language in noisy environments.

Her doctor believes that her habit of wearing noise-canceling headphones for up to five hours a day may be one of the causes of this problem. This neurodevelopmental issue is not hearing loss in the traditional sense, but rather an impairment in the brain's ability to process sound information.

Prolonged use of noise-canceling headphones may cause the brain to "forget" how to filter noise, especially during adolescence when the brain's complex auditory processing abilities are not yet fully developed. Claire Benton, vice president of the British Academy of Audiology, points out that being in this "false quiet environment" for a long time may delay the brain's ability to process speech and noise.

The profound impact of noise-canceling headphones on the auditory system

1. Decline in auditory processing ability

The brain trains complex functions such as sound localization and speech separation by continuously receiving environmental sound wave stimuli. When noise-canceling headphones block out low-to-mid-frequency environmental sounds (such as traffic white noise) for a long time, the activity of the superior temporal gyrus, which is responsible for processing sound, decreases, causing patients like Sophie to experience the phenomenon of "hearing sounds but being unable to interpret their meaning" in noisy environments.

The State Administration for Market Regulation found that 50% of noise-canceling headphones are insufficient in reducing low-frequency noise, forcing users to turn up the volume to over 85dB, further increasing the burden on the auditory system.

2. Impaired neuroplasticity

The auditory center of the adolescent brain is still developing between the ages of 18 and 25. Prolonged reliance on noise-canceling headphones reduces the input of acoustic difference signals between the two ears, affecting the brain's ability to build spatial auditory models. Research from Fujian Medical University shows that those who wear headphones for more than 4 hours a day have a 37% higher rate of auditory spatial localization error than the general population.

3. Safety and mental health risks

Noise-canceling headphones reduce ambient noise by an average of 15-20 dB, but high-frequency warning sounds (such as car horns) may still be filtered out. A 2023 Japanese traffic accident survey showed that pedestrians wearing noise-canceling headphones had an accident rate 2.3 times higher than ordinary pedestrians. In addition, prolonged isolation may trigger social anxiety; clinical data shows that 29% of those who overly rely on headphones experience a sense of alienation from reality.

Scientific protection recommendations

1. Follow the 60/60 rule

Keep the volume at 60% of the device's maximum output and do not use for more than 60 minutes at a time. If the ambient noise exceeds 85dB (such as in a subway car), it is recommended to stop using the headphones.

2. Choose compliant and suitable products

Prioritize headphones certified to the EN 50332-2 standard, with an active noise cancellation level of at least 10dB. Avoid "pseudo-noise cancellation" products with a noise cancellation level below 5dB. Also, choose over-ear headphones over in-ear earbuds, as over-ear headphones reduce direct pressure on the ear canal. Select headphones with good breathability and comfort to minimize ear discomfort.

3. Contextualized use

• In environments with steady-state noise, such as offices, noise reduction mode can be turned on;
• Switch to Transparency mode when walking outdoors to retain ambient sound above 2000Hz;
• Do not use in-ear headphones while sleeping; instead, use bone conduction devices.

Current research shows that qualified noise-canceling headphones, when used correctly, can still protect hearing. However, we must be wary of the hidden impact of "technology dependence" on neurodevelopment, as Sophie reflected after her treatment: "Learning to coexist with moderate noise is the key to balancing hearing health."

Note: This article is reprinted from 21db Acoustics.