PMC4060767_01
The Vibrant Soundbridge (VSB) implantable hearing device. The VSB system is comprised of two parts: the internal component is called the vibrating ossicular prosthesis (VORP) and the external component is an audio processor (AP). The VORP consists of a receiver coil, a magnet to hold the Amade audio processor over the implant, a demodulator, the conductor link, and the floating mass transducer (FMT). The receiver coil sends the sound signal from the audio processor to the demodulator or electronics package. The demodulator demodulates the signal so that it can be converted into signals that will drive the FMT. The conductor link just sends these signals to the FMT. Adapted from marketing materials on the VSB, with permission of MED-EL, Innsbruck, Austria.
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fig2
Y.H. was counseled regarding the risks and benefits of the VSB (Figure 2).
Unaided audiogram before surgery.
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fig3
The unaided audiogram for K.C. was indicated in Figure 3.
Unaided (U) and aided (A) soundfield audiogram obtained 3 months after the implantation of VSB in the right ear. Thresholds were measured with the warble tone signals presented from the poor ear (at 90 degree azimuths). The left (nonimplant) ear was plugged and muffed during testing.
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fig4
The results revealed no obvious change at any frequency.  Figure 4 presents unaided air and bone conduction thresholds before the surgery. With the VSB set at the most comfortable listening level, it was also shown that VSB offered functional gains of 5 to 20 dB across the frequencies from 500 Hz to 4 kHz, when compared with the unaided thresholds (Figure 4).
Speech reception thresholds (SRT) obtained in quiet using the Cantonese version of the Hearing In Noise Test (CHINT). SRTs were obtained unaided and aided at 3 months after activation of the VSB.
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fig5
With binaural hearing in quiet, there was a slight elevation of SRT (0.8 to 3.8 dB) when compared to the unaided conditions (Figure 5).
Speech reception thresholds (SRT) obtained in noise using the Cantonese version of the Hearing In Noise Test (CHINT). SRTs were obtained unaided and aided at 3 months after activation of the VSB.
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fig6
In noise, as shown in Figure 6, the use of the VSB implant did not improve binaural squelch in the noise front condition; that is, the SRT did not improve compared to unaided, probably because the gain of the implant was low and thus did not yield true binaural hearing.