1. SOUND PRESSURE LEVEL
82dB±3dB/1.0 w/0.1m at 800Hz,1000Hz,1200Hz,1500Hz average
2. IMPEDANCE:4±15% Ω(@1KHz 1.0V) .
3. MEASURING DIAGRAM: Shown in Fig.2
4. TYPICAL FREQUENCY RESPONSE CURVE: Shown in Fig.3.
5. RATED POWER:  0.5W
5-1.  MAXIMUM INPUT POWER:  1.0 W
6. RESONANCE FREQUENCY (F0): 180±20%Hz @ 1.0V.  Fig.4
7. DISTORTION: Less than 10% at 1KHz 1.0W（1.4V）.
8. BATTERY CAPACTIY: 250mA
9. TALKING TIME : ≥ 3.5H
10. STANDBY TIME: ≥ 12H