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How wireless headphones work
How music gets from your phone to your ears with no wire in between.
The short version
Your phone encodes the audio using a Bluetooth audio codec and sends the data to the headphones. A tiny computer decodes it, turns it into an electrical signal, amplifies it and drives a small speaker. Processing and buffering add a short delay. It builds on Bluetooth.
I always thought wireless headphones sent the music as sound.
They send numbers.
The sound only exists again inside your ear.
From file to ear
- The phone squeezes the music into a smaller amount of data, using a method called a codec.
- It sends that data by Bluetooth.
- A chip in the headphones unpacks it.
- A converter turns the numbers into a changing electrical signal.
- An amplifier makes the signal stronger.
- A tiny speaker, called a driver, moves back and forth and makes sound.
Why the delay, and the battery
Encoding, radio transmission, buffering and decoding can add a noticeable delay, which varies by device, codec and listening mode. Music is usually fine, but video or games can look out of step. Many video apps compensate by delaying the picture.
Each earbud also needs its own battery and radio, so they are small and last only hours between charges. The charging case is a second, larger battery.
Wired or wireless
A wired pair has no battery, no radio and no compression, so it is usually simpler and delays nothing. Wireless gives freedom of movement at the cost of a battery, a small delay and a codec. A better codec keeps more of the detail at the same data rate, but both your phone and your headphones must support it for it to be used.
Source: Bluetooth Core Specification
Note: the delay is usually small enough not to notice, but it matters for video calls and games, where a gap between sound and action is obvious.
Key takeaways
- Music is sent as compressed data, not as sound.
- The headphones rebuild the sound inside them.
- Each step adds a small delay.
- A tiny battery limits how long they last.
Now you know.
Music travels as numbers.
The earbuds turn them back into sound.
Every step adds a little delay.
Last reviewed 3 Nov 2026
