The Sound Pressure Level Signal Measurement Instruments Based On The Ears Canal

This paper involves a measurement instruments for medical hearing devices.Measurement instruments of medical hearing devices, including three parts:signal coupling, amplifiers, digital control system, in the simulated environment of the human ear canal, couples the sound pressure level signals into the circuit with a test microphone, we can evaluate the listening devices'performance by measuring sound pressure level signals.In the simulation ear sound pressure level signal is coupled into circuit board, and the simulation ear can be designed according to the International Electrotechnical Commission standards, couple cavity and the test microphone work closely together, meeting the sound pressure field environment of the sound pressure level measurement, which promote SPL signal coupling into circuit board fully.The amplifier amplify small signals and gives a frequency range for the measured signals: 20Hz - 20KHz, and the amplified signals must meet the LINEIN requirements of CODEC, this means the signal's voltage must be less than 1Vrms.Digital control system will control the amplifier gain, CODEC sampling and results showing.