Is that ringing in your ears caused by your noise-cancelling headphones? Here’s what you need to know

There are some very good reasons for wearing your AirPods or other noise-cancelling devices. Noise infiltrates your consciousness in every aspect of your life. You wake up to the sounds of your upstairs neighbours. As you begin your hustle for the day, the drilling and hammering from the renovating unit in your block have also begun.

And unless you want your inner peace to be interrupted by the ruckus from fellow commuters' handphones or unnecessarily loud phone conversations, you put on your trusty noise-cancelling gadget.

It isn't farfetched to say you might have your devices on for longer than six hours a day, if you also use them to ward off chatty colleagues in the office, block out lunchtime cacophony in the food court and get your adrenaline pumping in the gym.

For all that time you spend with your earphones or headphones, can your hearing be affected? You may have encountered reports that link noise-cancelling audio gadgets with tinnitus (a phantom ringing, buzzing or roaring sound) and wondered: Are you at risk?

HOW DO NOISE-CANCELLING GADGETS WORK?

Noise-cancelling devices have a built-in microphone to analyse the ambient sounds around you and generate the opposite sound waves to neutralise them. Generally, there are three audio devices that deliver this tech for the sweet, sweet sound of silence (or close to it): Earphones, earbuds and headphones.

The key difference between earphones and earbuds is their fit: Earphones insert into the ear canal, while earbuds rest on the outer ear. Of the three, headphones are probably the ultimate in noise avoidance because they also cup your ears for an added layer of noise-blocking.

WHAT'S WORSE: A NOISY ENVIRONMENT OR NOISE-CANCELLING GADGETS?

The quick answer: A noisy environment, said Soo Ying Pei, the head of Audiology at Alexandra Hospital. “Noise-cancelling devices, if used appropriately, wouldn’t be harmful to our hearing,” she said.

But if you max out the volume on your noise-cancelling earphones at 105 decibels (or dB) to 110dB for 5 minutes, for instance, “it could potentially cause noise-induced hearing loss, which is similar to that of someone being exposed to noisy environments”, said Soo, citing a 2020 Harvard study.

OKAY, BUT WHAT IS CONSIDERED LOUD?

These are sounds that measure 100dB and above, said Dr Neo Wei Li, an associate consultant with Department of Otorhinolaryngology - Head & Neck Surgery at Sengkang General Hospital.

Loud noises don’t only come from planes taking off; you can also hear them from fitness classes, the movie theatre, driving a motorbike or listening to music with headphones at a high volume. “For noise levels of 100dB and above, the limit is 15 minutes,” said Dr Neo.

Keep things at 85dB as it’s a safe level for you to be exposed to for up to eight hours, said April Chong, the director of Clinical Excellence (Training) and a senior principal audiologist at WS Audiology. The noise of a hairdryer, vacuum cleaner, noisy restaurant or a truck passing by are examples.

Once you get past 85dB, the safe listening duration is cut by half for every increase of 3dB, said Chong. For comparison, whispering is about 30dB, while a normal conversation is around 60dB, she said. 

In other words, the louder the sound, the shorter you should limit your exposure to it, according to Dr Neo.

WHAT HAPPENS IN REAL LIFE THOUGH?

Your eardrums could be taking a beating without you realising it. For instance, the noise level in a crowded bar could be 104dB to 112dB, said Dr Neo. At this level, sound “may damage your ears and higher volumes can result in hearing damage even with a shorter exposure”, she said.

“For occupational noise exposure, such as individuals who work at construction sites, guidelines suggest that they should not be exposed to 85dB and above for over eight hours,” said Dr Neo.

Even Taylor Swift could be busting your ears, according to Chong’s colleague, who measured the sound levels at one of the popstar’s concerts in Singapore last year with a decibel meter. “The safe listening threshold for anything above 100dB is about 15 minutes. These concerts go on for two to three hours!” she said.

WHAT ABOUT NOISE-CANCELLING GADGETS?

It could go either way. “While noise cancellation helps reduce background distractions, many users still increase the volume of their music in noisy environments, such as on public transportation or in shopping malls, to further mask the external sounds,” said Chong.

But, on the upside: "Studies show that in noisy environments, traditional earphone users tend to increase their preferred volumes, while users of active noise cancellation earphones do not,” said Dr Neo. “This suggests that noise-cancelling devices may help protect our ears."

Dr Gary Lee, the head of Audiology at Ng Teng Fong General Hospital, agreed. “Using headphones with noise-cancellation technology is better than normal headphones,” he said, “because if the headphones can cut out ambient noise, you wouldn’t have to turn up the volume of the music and therefore, decrease the risk of damaging your hearing.”

SO, HOW IS USING NOISE CANCELLING LINKED TO TINNITUS?

What is tinnitus in the first place? “Tinnitus arises when you perceive sounds in the absence of an external sound,” explained Dr Lee. But there is nothing wrong with you.

“These are internal sounds generated by the brain as a compensatory mechanism in an absence of auditory stimuli. It is a natural phenomenon,” said Dr Lee. In fact, nine out of 10 people will report hearing sounds when placed in a soundproof room for 10 minutes, he added.

Wearing noise-cancelling devices is a little like being in a soundproof room. Once the noise-cancelling earphones are removed and auditory stimulation returns (such as the hum of the air-conditioning or sound of traffic from the window), tinnitus disappears, said Dr Lee.

But have your hearing checked if tinnitus bothers you. “One common cause is high frequency hearing loss, which leads to increased activity in the brain, potentially causing phantom sounds,” said Dr Neo.

SHOULD YOU LIMIT YOUR USE OF NOISE-CANCELLING DEVICES?

“The prolonged usage of these devices might cause earwax buildup as the ears are occluded,” said Soo. “As the ears are occluded, heat and sweat buildup might increase the risk of ear infections.”

She continued: “Also, you may develop a dependence on these devices where their absence can cause anxiety and frustration”.

Dr Lee brought up another point. “Without being able to hear ambient noise reduces our situational awareness and ability to respond to safety signals,” he said. “Hypervigilance to sounds is also not a good habit as it leads to hyperacusis, which is an abnormal intolerance to every sound.”

To play it safe when using your noise-cancelling gadgets, Soo recommends switching to the transparency mode such as the one on AirPods to allow some degree of background noise. “The goal is not to totally mask external noises but to improve your ability to ignore them,” she said.

As for the volume, the World Health Organization recommends no more than 40 hours of sounds at 80dB or higher for adults, and 75dB for children, cited Dr Neo. However, “a study found that many young adults listen at volumes between 71dB and 105dB, with up to 58 per cent exceeding safe limits,” she said.

A good rule of thumb, said Dr Neo, is to keep the volume on personal audio devices at no more than 60 per cent of the maximum level.