Hearing loss may not be a common symptom of the COVID-19 disease. However, as people stay and work at home during the pandemic, and make greater use of personal audio and video devices, hearing-related problems could well become associated with the condition.
“Excessive exposure to sound energy damages the delicate outer and even the inner hair cells of the cochlea. Prolonged exposure results in permanent hearing loss,” said Dr Joyce Tang Zhi En, Associate Consultant, Department of Otorhinolaryngology – Head and Neck Surgery, Singapore General Hospital (SGH).
To illustrate the damage that can occur from listening to audio devices, consider that the output of personal audio devices can range from 75dB (decibel) to as high as 120dB. Occupational noise exposure, which sets a rough minimum standard for people working in a noisy environment, considers exposure to 85dB over eight hours a day hazardous to hearing. For workers, regular breaks from their noisy workplace are essential.
There are no data to show whether the use of personal devices has increased since the start of the pandemic, but Dr Tang said that tech use was already steadily rising prepandemic. In the United States, headphone use rose 75 per cent between 1990 and 2005, while hearing loss among teens there increased to 5.3 per cent in 2006 from 3.5 per cent in 1994. The 2010 Singapore National Health Survey, meanwhile, showed that nearly 13 per cent of 18 to 29-year-olds have mild hearing loss in at least three of four tested frequencies in at least one ear, said Dr Tang.
The World Health Organization (WHO) said adults should aim for sound levels of less than 80dB over 40 hours a week, and 75dB over 40 hours for children. Studies found that between six and 25 per cent of listeners are exposed to volumes of more than 90dB, with five per cent going beyond the 100dB mark.
A 2014 Singapore study involving 2,000 tertiary students found that 16 per cent of participants listened to portable music players at sound levels of more than 85dB for eight hours, putting themselves at risk of permanent noise-induced hearing loss.
Children, too, are increasingly exposed to technology at a younger age, with damage to noise appearing later in life. “As children’s hearing is more sensitive, it is imperative to ensure they develop healthy habits when using devices,” said Dr Tang, adding that the WHO estimated half of 12 to 35-year-olds to be at risk of hearing loss due to exposure to unsafe levels of sounds from personal audio devices.
Deafness and dementia
Sensory dysfunction is closely linked with cognitive decline, with hearing loss having one of the most important associations with dementia. This is because the sensory system, including sight, hearing and smell, has an intricate relationship with cognitive function. Our eyes, ears and nose are closely linked with brain via the neural network, said Dr Vu Tai Anh, MD-PhD student, Duke-NUS Medical School.
“Brain stimulation from our senses is restricted in sensory loss, thereby increasing the risk of cognitive decline. Poor sensory functions may also result in social isolation, in which people may be less willing to leave their house, see friends, and participate in mentally stimulating activities. Limited social interaction, in turn, has been linked with a higher risk of dementia,” he said.
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Headphones are generally better for ear health than earphones.
Sounds from earphones range between 80dB and 120dB, and if
inserted deep into the ear canal, the level can reach the upper limit.
As headphones are farther from the ear canal, they deliver sound that
is as much as 9dB lower.
Noise-cancelling earphones or headphones allow listening at
softer volumes even in noisy environments like trains. For children,
special headsets allow volume to be limited.
Still, the volume and duration of sound exposure are important.
“Most guidelines recommend limiting sound exposure to 60 per cent
of maximum volume for up to 60 minutes a day. As a guide, while
on headphones, you should still be able to hear someone talking
to you at arm’s length,” said Dr Joyce Tang, Associate Consultant,
Department of Otorhinolaryngology – Head and Neck Surgery, SGH.
Much like eye breaks from computer work, it is important to
schedule regular audio breaks of at least 15 to 20 minutes. “This
helps the delicate cochlear hair cells
recover from the oxidative stress of
loud sounds, and reduces
the risk of hearing loss,”