Matt Thomas, an animator and motion graphics designer in London, is a convert. He discovered he could use the silencing feature on its own one day by accident, when his music cut out on the tube: “I thought, wait a minute, there’s this really nice peace and quiet. It was like that moment in a film where the sound cuts out and everything goes into slow motion.”
Heavy traffic generates noise levels of up to 85 decibels (dB), which the UK's Health and Safety Executive deems sufficient to cause permanent hearing damage if we’re exposed to it for several hours every day. Underground trains can pass the 100dB mark when roaring around a loud corner.
Thomas often puts his headphones on silent when on public transport (he no longer does this in the street after nearly getting run over), but prefers music for work. For Johanna Vogel, an economist in Vienna, Austria, it’s the opposite: she plays music on the bus but works in silence. Vogel bought her noise-cancelling headphones hoping they would help her concentrate in an open-plan office. “It’s so relaxing,” she says. “At first I was doubtful it would make a big difference, but now couldn’t live without them. In noisy environments I really need some way to create quiet for myself.”
Noise damages more just our ears. Research studies have found links between long-term noise exposure and increased risk of heart attack and stroke, as well as low mood and difficulties with sleeping and concentrating. Adverse effects on mental and physical health can start at just 65dB, a level that seems moderate: a refrigerator hums steadily at 40dB, and an open plan office buzzes at around 60dB.
Josi Livingston, a developer at a technology startup in London, often uses the silencing feature to block out office chatter while she’s coding, but likes how she can still hear if someone talks to her. “I’m trying to minimise distraction. I need to focus, and any kind of extra stimuli will detract from that,” she says. “I think of it as engineering my environment to be the most comfortable.”
Unwanted noise can cause irritation and anger if it feels like an invasion of privacy, says Stephen Stansfeld, a Professor of Psychiatry at Queen Mary University of London who focuses on noise and health. “Having a lot of background noise when you’re doing something is tiring. Without noticing, you’re putting in a lot more effort in order to block out the noise. So when you shut it out, there’s a sense of relief.”
Getting worked up about noise can raise stress levels and leads to ill health. “But there’s no doubt that even if you’re not focused on the noise, it can still have an effect. If you’re asleep you may not wake up, but your body is still responding if you hear a loud sound,” says Stansfeld. “The body responds to noise as a stressor.”
Bethany Temple, an attorney in Raleigh, North Carolina, sometimes uses her headphones to avoid having to hear the TV when she’s at home with her husband. Temple says the silencing feature helps her feel more centred in herself: “When you realise just how much ambient noise there is everywhere: the refrigerator is running, the dishwasher, the washing machine and air conditioner, cars are going by outside. When that goes away, and you have the ability to be silent with your thoughts – once you realise that exists in the world, you start craving more.”
Noise-cancelling headphones were originally created for airplane pilots to improve their comfort on long flights, and the first consumer versions were also intended for travellers.
The technology, known as active noise-cancellation (ANC), works by using microphones to pick up low-frequency noise and neutralise it before it reaches the ear. The headset generates a sound that’s phase-inverted by 180 degrees to the unwanted noise, resulting in the two sounds cancelling each other out.
ANC headphones turn down the volume of the world by about 30dB, says Brian Brorsbøl, Director of Product Management at Sennheiser Communications – the reduction ranges between 20dB and 45dB, as the technology is more efficient against low-frequency sounds. “Using noise-cancelling technology on its own is something we’ve heard some people are doing,” he says.