Sensitivity and fidelity of a novel piezoelectric middle ear transducer.
OBJECTIVE
A novel implantable piezoelectric transducer has been developed in this laboratory. The transfer functions of the transducer were assessed in anesthetized acutely implanted cats, and were compared with the microphone of a cochlear implant's speech processor.


METHODS
The piezoelectric transducer was fixed to the head of the malleus of the cat. Pure tone signals of 97 dB SPL ranging from 250 to 8,000 Hz delivered from a loudspeaker placed beside the auricle of the cat were used to vibrate the tympanic membrane. The frequency response of the transducer was measured by monitoring the output signal of the transducer with an oscilloscope. The transfer functions of the transducer were then compared with the standard external microphone receiving the same tonal stimulus.


RESULTS
The average sensitivity of the implantable piezoelectric transducer was -38.7 dB re 1 V/Pa at 1,000 Hz. The frequency-response curve of the transducer mirrored that of the external microphone, even with high-frequency stimuli.


CONCLUSIONS
The implantable piezoelectric transducer developed in this laboratory transmits tonal stimuli with high fidelity.
Chi
Fang-Lu
FL
Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, PR China. chifanglu@yahoo.com.cn
Wu
Yongzhen
Y
Yan
Qin-Bo
QB
Shen
Yi-Hu
YH
Jiang
Ye
Y
Fan
Bao-Hua
BH
D000818:Animals; D001309:Auditory Threshold; D002415:Cats; D003054:Cochlear Implants; D004432:Ear, Middle / Q000601:surgery*; D004560:Electricity; D005583:Fourier Analysis; D008307:Malleus / Q000601:surgery; D011474:Prosthesis Design; D013018:Sound Spectrography; D014159:Transducers; D014732:Vibration