The working principle of the Bluetooth headset can be roughly divided into four steps as shown in the figure:

1. The decoding chip in the mobile phone decodes the music file such as MP3, generates a digital signal and sends it to the Bluetooth headset through Bluetooth;

2. The Bluetooth headset receives the digital signal and converts it into an analog signal that the adult ear can understand through the digital-to-analog conversion chip inside the Bluetooth headset;

3. To amplify the analog signal, a signal amplification chip inside the earphone is needed;

4. The earphone unit receives the amplified signal and makes a sound, and the ear hears the music