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This paper focuses on transducers, which are the most important components of bone conduction implants. To improve vibration magnitude, we develop a coil vibration transducer in which the driver mass loading is reduced by about 3.25-fold compared to magnet vibration transducers. We use finite element analysis to derive and implement the maximum Lorentz force and frequency characteristics. We compare the effect of driver mass loading on the vibration magnitude to that of an older transducer. The new transducer vibrates about 4.4-fold more strongly. To compare force magnitude between the two transducers, output force is measured using an artificial mastoid. The force imparted by the new transducer is higher than that of the older transducer only below 1.4 kHz, and tends to be lower at high frequencies. Nevertheless, the improved force in the low-frequency region will improve conductive hearing loss.

The BAHA® Softband has been developed to provide a transcutaneous anchor for a BAHA® until a child is a surgical candidate for the percutaneous BAHA® implant. We tested the objective output force level of the BAHA® Classic 300 and Compact connected to a Softband on an artificial mastoid to determine: (1) the effects of direct contact force on output force levels (dB); and (2) the required volume control setting to ensure audibility of speech (assuming an average adult reference equivalent threshold force level). Direct contact force was varied from 2 to 5 N in 1 N steps. Output force level increased with increasing contact force. However, the average increase was 3 dB or lower, suggesting that the contact force is of minor importance. Volume control setting appears to be of much greater importance. It is suggested that the volume setting of either device be set to at least 2.5 to ensure audibility of conversational speech. Data from normal-hearing adults with simulated conductive hearing losses are presented to validate this conclusion. [ABSTRACT FROM AUTHOR]