Burn-in: myth or real?

You read it all the time on forums and in reviews: new headphones sound harsh or boomy at first, and after a while they 'open up'. The numbers for how long that takes vary from a few hours to hundreds. Some people play pink noise through a new set for days before listening to it properly.

The idea isn't silly. A dynamic driver is a cone held by a flexible surround. New materials can be a little stiffer at first, like new shoes. The question is whether that changes enough to hear. You can measure that, and people have.

The best-known test comes from RTINGS. They took four new headphones with different drivers: the AKG Q701 and Beyerdynamic DT 1770 (dynamic), the Audeze LCD-2 Classic (planar) and the Etymotic HF5 (an in-ear with a balanced armature). Each one sat on a measurement head in a closed box and wasn't touched for 120 hours. They played a short sweep, then 50 minutes of pink noise at 90 dB, then 10 minutes of silence, over and over, and measured along the way. Their conclusion: no evidence of a break-in effect. What they did measure was too small to hear.

Earlier, Tyll Hertsens of InnerFidelity did something similar with a new AKG Q701. He measured it straight out of the box and then at set points up to 90 hours. He saw small changes around the driver's bass resonance and in distortion, mostly early on. His own conclusion was careful: this did not show that break-in exists, and if it does, it's a small effect.

RTINGS points out that four headphones don't make a law, and there are thousands of models. But the direction is clear. If a driver changes at all, it's by little, and mostly in the first hours.

Much of what people hear as burn-in isn't in the driver but in what holds it against your ear.

• Foam tips are stiff at first. After a few weeks they're softer, expand faster and seal differently. The seal decides much of how much bass you hear. After a few months they wear out, as our ear tip guide explains.
• Headphone ear pads compress. The driver ends up closer to your ear and the pads seal differently. That mainly shifts the bass, and sometimes the treble. On the Audio Science Review forum, Solderdude, who measures a lot of headphones himself, points to this as the explanation for many break-in stories.
• Silicone tips hardly change. If silicone tips sound different after a week, first check that they sit as deep as on day one.

The second explanation sits between your ears. Every headphone and IEM has its own tonal balance. On day one a treble peak or a thick bass stands out because you're used to something else. After a few days it's your new normal. Many listeners notice the reverse too: go back to your old set after a week and it sounds odd for a while.

That isn't imagination. You really do hear something different. The change is just in how you listen, not in the device. Your memory for small differences in sound is also short, so comparing an impression from last week with what you hear now is hard.

1. Get the fit right first. Try every tip size, per ear. A leaking tip costs more bass than any driver ever will.
2. Just listen to your own music at your normal volume. That breaks the set in by itself, as far as there is anything to break in.
3. Don't run pink noise at high volume. It achieves nothing normal listening doesn't, and it puts needless strain on the driver. If you do it anyway, keep it moderate and not in your ears.
4. Give your ears a week before you judge. You have 30 days to return with us, so that week fits easily.
5. Compare at matched volume and switch quickly. A slightly louder set easily sounds 'better', even when the difference is under 1 dB. Use short pieces of music you know well.