BONE CONDUCTION TRANSDUCER/RECEIVER

Typical Number in Hospital:

Cost Bands:

References: 8

Also known as a bone vibrator, this is an electromagnetic transducer which is normally positioned behind the ear on the mastoid bone and kept in position by a sprung headband. When fed with audio frequency signals it imparts a corresponding vibration to the skull and thence to both inner ears. It has two principal applications:

1. As an output device for an audiometer used in audiology departments. This can be used for testing patients' hearing as an adjunct to testing with conventional earphones (known as air conduction). Comparison of the results thus achieved enables the clinician to distinguish whether a hearing loss is attributable to the external or middle ear (a conductive loss) or inner ear (sensory loss).

2. Some patients who wear a hearing aid cannot wear an ear mould which is the normal mechanism for coupling the hearing aid to the patient's ear. Instead its output is routed via a bone vibrator. The main disadvantage of this transducer is its very high distortion, its limited output, and its relative discomfort and obtrusiveness.