1.Headphone: 

a)Frequency response: 125Hz~8000 Hz, ±17 dB(0dB=20uPa)(input power =1mW) 

b)Impedance:32Ω±20%; 

c)Characteristics of sound pressure level(sensitivity):≥100dB/1mW (0dB=20uPa).                                                                                

2.Microphone:

a)Frequency response.  

b)Type: electret microphone;  

c)Free field sensitivity:-47±2 dB(0 dB=1V/Pa); d)Directional type; bidirectional.