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. CONCLUSION: The implantable piezoelectric transducer developed in this laboratory transmits tonal stimuli with high fidelity. 2009 S. Karger AG, Basel
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. CONCLUSION: The implantable piezoelectric transducer developed in this laboratory transmits tonal stimuli with high fidelity. 2009 S. Karger AG, Basel