Introduction 13 1 The processor is comprised of a microphone, amplifier, digital processor, and a transducer. Here, sound is converted into a digital signal which drives a floating mass transducer. This vibration energy is then transmitted to the skull by the proximity of the vibrating processor to bone. Over time the footprint of the processor has reduced (34mm to 26mm), as has the technological application and connectivity to other electronic devices such as smart phones and computers. The processor can be held in place on the mastoid bone by either non-surgical or surgical options and can be provided either unilaterally or bilaterally in the treatment of conductive hearing loss, mixed hearing loss or a single sided sensorineural deafness. Non-Surgical Hearing Systems Non-surgical mounts have been widely applied due to their simplicity, flexibility, and low cost. They are easily removable and replaceable based on the social or acoustic needs of the patient. The simplest solution uses a soft headband made from stretch fabric which is washable. An alternative to this is a hard headband mount which provides a greater contact pressure than the softband. It has been demonstrated that although a pressure of 2N is required to ensure an effective transmission of bone conducted sound [11] increasing the contact force provided limited (< 3dB) gain and that it is volume rather than contact force which is of greater importance [12]. Therefore, a softband is preferrable because of improved patient comfort and wearing time. Softband options are provided by Oticon TM supporting the Ponto processor, Cochlear TM Baha® Start, Alpha MPO ePlusTM and the contact mini-TM (BHM Austria). In the 1960’s technological improvements reducing the size and weight of the electronic component allowed the sound processor to be mounted to spectacles. This type of mount still exists today and can provide both unilateral and bilateral mounting options and is particularly useful if eye glasses interfere with standard behind the ear hearing aids. More recently the Sound Arc (Baha® Cochlear) was released, designed to be worn above the ears and behind the head. A semi rigid light-weight frame holds a connection disk in place to which the processor is mounted, and this again can be bilateral if required. This style of device has gained popularity in recreational sports where the application of bone conduction headphones (Shokz [13]) allow for an open ear canal. This is particularly useful where the user wishes to remain aware of their surroundings while undertaking a sporting activity such as running or cycling. Although audiologically effective, subjective feedback from patients demonstrates poor compliance with headbands due to concerns about the aesthetics. This can be a particular deterrent to many older children with self-perception issues and concerns about integrating
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