Safe listening levels for headphones are lower than you might think. In fact, the NHS warns that listening to headphones too loudly is 'one of the biggest dangers to hearing'.
Many smartphones come with safe-listening-level indicators when using headphones. But as some models can be much louder than others, it's only a guide. Noise-induced hearing loss can be irreversible and although hearing aids can help, they won't restore hearing to normal.
Keep reading to learn more about the dangers, plus how you can keep your ears healthy with the right techniques and headphones.
In the UK, hearing loss affects one in six adults, according to an NHS report. And last year, the World Health Organization (WHO) warned that more than one billion people worldwide are at risk due to unsafe listening.
The NHS recommends that you listen at no more than 60% of the maximum volume on your device, and to not use earphones or headphones continuously for more than an hour at a time, taking a break of at least five minutes every hour.
But we spoke with audio design expert Dr Lorenzo Picinali, from Imperial College London, who warns that 60% could already be too much.
WHO recommends a safe daily limit from all sources of sound of 85 decibels (dB) - equivalent to the noise of a food blender or heavy traffic - for a maximum of eight hours. But, according to WHO, personal audio devices can output sound as loud as 136dB.
The fact that decibels don't rise in a linear way makes this more worrying. An 88dB sound is twice as intense as a 85dB one, so you could only listen to this safely for four hours. At 136dB, just seconds of exposure can cause irreparable damage. Since high-pitched sounds are affected first with hearing loss, you might not notice immediately - and could easily make the damage worse before you realise.
Excess noise causes fatigue to the ear's sensory cells and can cause temporary hearing loss or tinnitus (ringing in your ears linked to hearing loss).
Prolonged listening can raise the risks, too, as the sensory cells in your ears can only take a certain 'dosage' of sound - so it's both the loudness and duration that count. When exposure is particularly bad or lengthy, it can result in irreversible hearing loss.
To find out how to keep your ears safe, Which? video reporter Reya El-Salahi visits audiologist and social media star Neel Raithatha aka The Wax Whisperer.
Better habits for headphone listening doesn't need to mean giving up music. Choosing headphones with better sound clarity means you're less likely to raise the volume by too much to hear everything well.
If you choose a pair that form a good acoustic seal around your ears (such as in-ear headphones with flexible eartips rather than earbuds), or a pair with active noise cancelling, you may not raise the volume as much.
Dr Picinali warns to be mindful when raising the volume to compensate, as your hearing adapts to the new volume. And the volume can change between audio sources as well, for example between podcasts and music. So if the background noise stops or you notice the sound from your headphones becomes louder, make sure you turn down the volume.
Our lab tests noise cancelling using a synthetic reference ear and expert listeners, simulating noisy places, such as the London Underground.
If you use your headphones in noisy places, such as on the train or while exercising, consider ones with active noise-cancelling. We've selected some models to consider below.
These active noise-cancelling headphones have microphones that listen to background sounds and generate opposite sounds to cancel these out. A foldable design means you can tuck them into your bag if you're on the move.
Built-in touch controls on the headphones will save you from reaching for your smartphone. These let you quickly play and pause music, adjust the volume or skip tracks.
Apple's noise-cancelling 'Pro' headphones might be on your shortlist if you're shopping for a wireless, in-ear option. These buds are water-resistant, which means they will survive a trip to the gym or a walk in the rain.
Like the regular AirPods, these headphones use pressure-sensitive sensors to give you hands-free control over your tunes. A single press will pause a song, while a longer press will activate or deactivate the noise-cancelling effect.
Noise-cancelling technology doesn't always come cheap, but JBL has created an attractive package here. The JBL Live headphones, which support Amazon Alexa, Apple Siri and Google Assistant, are an option if you're on a budget.
These headphones arrive with an on/off toggle for the noise cancellation, although it's worth noting that you can't adjust the strength of the effect.
Sony has managed to bring its noise-cancelling technology to a particularly small pair of headphones. If you don't like the bulk of over-ear models, this in-ear pair might catch your eye.
The WF-1000XM3 headphones support Alexa, Google Assistant and Siri. With built-in near-field communication (NFC), you can pair them with a smartphone simply by tapping the two gadgets together.
These wired headphones don't have noise cancelling, but they do form an acoustic seal. This aims to block out background noise, so you won't need to raise the volume so high.
You get small earcups on these headphones, which means they sit on the ear for most people, rather than surrounding it.
Volume limiters on phones should only be used as a guide. They usually work by limiting the output driving headphones.
But since some headphones are more efficient than others, certain models sound louder than others at the same device volume. This means you could still damage your hearing, even if you've set the volume below the limiter.
Instead, you need to be aware of the need to raise the volume to a comfortable level for you and no higher.
Since in-ear headphones are so close to your ear drum, you hear the sound up to 9dB louder than with over-ear headphones at the same device volume.
In-ear headphones with flexible eartips are better than earbuds as they block outside sounds, so you don't need the volume so high. But these types of headphones can also prevent earwax from leaving the ear canal naturally, so avoid using them for long periods; the warm and moist conditions can provide the perfect breeding ground for nasties, including bacteria, warns audiology expert Dr Robert C MacKinnon.
Apps are available to enable you to monitor your listening 'dosage', helping you to decide when your ears should have a rest.
On Apple devices, there's a Headphone Audio Levels feature in Apple's Health app. And on Android phones, Sound Amplifier works with wired headphones, which should make audio clearer and easier to hear.