1.Max Sound Output: 129dB ± 4dB
2.Max Sound Gain: 45dB ± 5dB
3.Harmonic Wave Distortion: ≤5%
4.Input Noise: ≤30dB
5.Frequency Range: 450HZ~3500HZ
6.Working Voltage: 1.5V
7.Working Current: ≤3.0mA
8.Battery: AG13 or A675
Special Function Key: N-H Adustement,USA Knowles speaker