earphone gain

例句：

1. 1.The engineer adjusted the earphone gain to improve sound quality.
   工程师调整了耳机增益以改善音质。
2. 2.The speaker system needs to have a proper earphone gain for optimal performance.
   扬声器系统需要适当的耳机增益以获得最佳性能。
3. 3.The music player has a built-in feature that adjusts the earphone gain based on the volume level.
   音乐播放器内置了一个功能，可以根据音量水平调整耳机增益。