| The study is funded by the subject which is named "Piezoelectric-driven bone conduction hearing device mechanism and key technology research"(20070538). The subject is one of technology development projects in Jilin Province. The study combines the principle of bone conduction with the inverse piezoelectric effect of piezoelectric materials to design of piezoelectric bone-conduction hearing device supported by circular-leaf spring. We will study the following by the prototype theoretical analysis and experimental testing, such as supporting component, support column, rubber ring, base, roof. The main content of this article is as follows:1.The application and research condition of the bone conductionBone-conduction hearing device is currently divided into two categories, such as electromagnetic bone-conduction hearing device and piezoelectric bone-conduction hearing device. The piezoelectric bone conduction hearing device is a new bone conduction hearing device which has a compact structure, low power consuming and non-magnetic radiation, etc. The piezoelectric bone conduction hearing device has a very good future because of its advantages. However, the piezoelectric bone-conduction has its infancy. The device has not yet reached loudness requirements.2.The theoretical research of the piezoelectric bone-conduction hearing deviceDescribe the basic theory of hearing that include the construction of the human ear, production and characteristics of sound, and the valve of listening and other aspects of knowledge. Detail description of the piezoelectric effect, the vibration mode of piezoelectric ceramic chip, the resonant characteristics of piezoelectric vibrator, piezoelectric performance parameters, the equivalent circuit of piezoelectric vibrator and the typical supporting mode of piezoelectric.3.Study of the supporting form of sound elements and the choice of sound elementsUse Ansys to do static analysis and modal analysis of the different supporting form of piezoelectric. Discovering the piezoelectric vibrator using spring supporting form is Second-order system with two natural frequencies, and the spring supporting form can improve the loudness. Choose diameter of piezoelectric vibrator basis of the spring supporting form. The piezoelectric vibrator's piezoelectric ceramic has the same diameter as substrate.4.Design of the structure of each component of hearing deviceAccording to characteristics of supporting form and piezoelectric vibrator we design every components of the device through the method of theoretical analysis and experimental test, such as supporting component, supporting column, rubber ring, base, roof, circular sheet spring, determination methods of the spring elastic coefficient, ect. Manufacture piezoelectric bone-conduction hearing device prototype supported by circular-leaf.5.Performance testing of the deviceThrough theoretical analysis and experimental test a combination of device pitch, loudness, timbre, noise, analog performance and related testing of baking characteristics. Thus confirming the piezoelectric bone-conduction hearing device using the circular leaf springs supporting form is a second order system and has two natural frequencies; Piezoelectric bone-conduction hearing device's natural frequency is variability in the presence of a static force; Rubber ring can adjust the damping of hearing devices in order to reduce the effect of the natural frequency; The hearing device for receiving voice signals has good fidelity and deliveries the signal timeliness; Through the Noise test the device is not only respect of the use of hearing request, but also not cause damage to human health; Recommended under PRC Ministry of Electronics Industry Standards For Measurement methods of bone- conduction hearing aid provision, the hearing device input sound pressure level of 90dB frequency response of the output power level and full files of the frequency response test, so we can study the output power and sound-force sensitivity of the hearing device.
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