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14 July 2021

How we test headphones

Discover how our experts test headphones for sound quality and comfort. Only the very best earn our Best Buy award.
Oliver Trebilcock

What makes Best Buy headphones?

Which? examines everything that matters for headphones; including sound quality, comfort and how well they work in real life – so you'll know exactly what to expect. Our unique, comparative lab tests mean you can trust our Best Buy and Don't Buy verdicts and choose with confidence.

We put all the headphones through the same tests - providing consumers with impartial advice - which means that if a product isn't any good we'll say so, without fear of penalty. Which? works for you, providing trustworthy advice without a hidden agenda.

  • What's the sound quality like?
  • What's the comfort and fit like?
  • Do they suffer from sound leakage?
  • How durable are they?
  • Should I buy them?

Head straight to our headphone reviews - or read on to find out more about how we test to answer each of these questions.

What's the sound quality like?

To test sound quality we use a listening panel of five experts. They assess each pair of headphones using nine set audio tracks, covering a range of music and radio genres from pop and spoken word to classical and jazz.

What's the comfort and fit like?

How the headphones sound isn't our only consideration – we also assess them for comfort and how adjustable they are.

Our five lab experts rate these aspects, taking into account placing them in or on your ear, removing them from your ear, the potential of the headphones to accidentally fall out of your ear, and how restrictive the wire is. While doing these assessments, the ergonomists also consider how suitable the headphones are for left handed users as well as those with weak grip, poor sight, poor hearing and colour-blindness.

How do we test noise cancelling?

Headphones designed for travelling often have active noise cancelling technology that cancels out unwanted sounds like aircraft and railway noise so you can listen undisturbed. However, we've found noise cancelling so poor you'd barely notice it's working at all, so it's important to know the best pairs to choose, particularly since many noise cancelling headphones cost well over £100.

We test noise cancelling in two ways. Firstly, our lab uses a synthetic reference ear to test a headphone's noise cancelling under lab conditions. Secondly, our professional listening panel, with a range of ear sizes and ages, try out the noise cancelling themselves and assign an agreed rating on their performance and give their verdict. 

We test the noise cancelling using real-world recordings, including one of the London Underground on both trains and platforms, so you can be sure our Best Buy headphones really deliver.

How durable are they?

We rate the quality of the material used to construct the headphones and any areas of obvious concern.

The headphone cables are stress tested, to replicate getting them caught on arms or around your neck - to make sure they're strong enough, as well as assessing how tangled they get.

Do they suffer from sound leakage?

Our scientists use a calibrated reference ear to accurately test the headphones for how much sound leaks out to your surroundings while in use, to ensure you don't buy a pair that'll annoy those around you. Our expert listening panel also subjectively assess the headphones for sound leakage while in use, listening for any loud or irritating noises or tones.

How long does the battery last?

Bluetooth headphones, which allow you to connect to your devices wirelessly, have batteries built in. As do wireless dedicated TV headphones with a dock. Manufacturers make all sorts of battery life claims, but you shouldn’t always believe them – our real-life independent tests show they can be greatly different in reality.

In our tests, we set the headphones playing and time how long it takes the battery to run out, so you have figures tested in exactly the same way to compare from model to model across all the brands. We’ve even found headphones that will barely last an hour per charge, and some that’ll last 40 hours or more.

At Which? we wouldn’t usually award Best Buys to products that don’t have user-replaceable lithium ion batteries. However, there are currently very few wireless headphones that allow you to replace their batteries yourself, so this doesn’t affect our recommendations for headphones.

Should I buy them?

We give every pair of headphones a Which? test score so you can immediately see at a glance which are the best and worst, plus how each model compares in regards to features and specifications. The headphone score ignores price and is based on the following criteria:

  • 60% sound quality
  • 15% comfort & durability
  • 15% audio enhancements
  • 10% features

Headphones need 70% in our tests to earn our Best Buy recommendation. Headphones that score 45% or less are highlighted as Don't Buy models to avoid.

Will they last?

As well as our tough lab tests we also assess how reliable headphone brands are in our annual member survey. Each year we get data on over 50,000 devices - including more than 1,800 headphones - and use this to determine which products are built to last. If we find that headphones from a brand are unreliable and likely to experience a fault then we won't name them as Best Buys, no matter how well they did in our lab assessment.