Directionality is a proven way to improve signal-to-noise ratio and thereby speech understanding in noise for hearing instrument users. Unfortunately, directionality does not come without some drawbacks. Because of the relatively small microphone spacing on hearing instruments, long wavelength low frequency sounds tend to get cancelled regardless of which direction they come from. This means that directional microphone systems are less sensitive in the low frequencies and accounts for the well-known low frequency roll-off associated with directionality. If no compensation is made for this roll-off, audibility of low frequency sounds may suffer and the overall sound quality may seem tinny. If gain is boosted to compensate for the low frequency roll-off, the noise floor of the hearing instrument is overamplified - an effect which can be audible and annoying for the wearer.
The Surround Sound Processor is designed to promote good speech intelligibility and natural sound quality by preserving the acoustic characteristics of the open ear. In last month's column, we wrote about how the Surround Sound Processor contributes to better spatial hearing compared to traditional directionality or omnidirectionality with BTE microphone placement. Another great advantage of the Surround Sound Processor is that it provides directional benefit without compromise regarding audibility or sound quality. This unique system applies directional processing to high frequencies and omnidirectional processing to low frequencies. The frequency at which this split occurs is prescribed individually and can be adjusted in the Aventa fitting software. This processing strategy replicates directionality patterns of the unaided ear even for BTE microphone placement, contributing to natural perception of sound for the user.
>>Click the link to hear a demonstration of how the Surround Sound Processor maintains superior sound quality while providing directional benefit for the wearer.