Vincent Cumberworth BSc FRCS Consultant Ear, Nose and Throat Surgeon
Clementine Churchill Hospital Sudbury Hill Harrow Middlesex HA1 3RX
Private Secretary: Tel: 020 8872 3866 Fax: 0208872 3861

Information is supplied only upon the condition that the viewer will make their own determination as to the suitability of the information for its purposes prior to use.  There will be no responsibility for information that is misused or misinterpreted and the information should not be used as a substitute for consultation with a health care professional.  It is not possible to answer questions regarding individual cases or to enter into individual correspondence.

The Investigation And Management Of Hearing Loss

Sound is transmitted through the middle ear into the cochlea; in the inner ear the sound waves are converted into electrical signals.  These then pass by nerves to the brain.  The commonest cause of hearing loss is due to damage to the hair cells in the cochlea and accounts around 80% of such problems.  In excess of 7½ million people in the United Kingdom have some degree of hearing loss with the common factors being age, infection or excessive noise exposure.

Types of Deafness

Conductive deafness involves a problem affecting sound passage either down the external ear canal or across the middle ear, such as excessive wax, fluid in the middle ear, perforation of the drum or damage to the sound conducting mechanism.  This type of hearing loss may be, although not always, correctable.

SensoriNeural Hearing Loss

Sensorineural hearing loss is due either to problems at the cochlea (“sensory”) or at the auditory nerve (“neural”).  This condition is most frequently helped by a hearing aid, although sometimes other treatments are possible. Middle ear implants for this problem are not widely used and often not appropriate as a first line treatment.

Certain types of sensorineural hearing losses do require urgent ENT review, particularly in cases where there is a sudden severe loss, or rapid deterioration over hours or days, and is there is any association with discharge from the ear, pain or dizziness.  Urgent medical treatment can sometimes benefit early onset cases of severe sensorineural hearing loss and the association with other symptoms can necessitate urgent investigation to exclude (or diagnose and treat) any potentially serious complications.  An acute sensorineural hearing loss, which may warrant urgent investigation and treatment, may masquerade as a conductive loss.

Analogue Hearing Aids

Hearing aids are able to help around 5 million people in the United Kingdom.  The initial referral from the general practitioner is generally to an ENT Surgeon or Audiologist and further hearing testing is likely to be arranged.  If there is any asymmetry in the hearing thresholds, a significant conductive component or any other associated symptoms, then review by an ENT Specialist will be necessary.

A hearing aid consists of a microphone to detect sound, an amplifier to increase it and a speaker to transmit the amplified sound down to the ear.  They cannot restore hearing to normal and the “mould” needs to be tight fitting to minimise feedback (producing whistling) and this can cause a mild discomfort when initially using an aid. If this is prolonged, or severe, then adjustment of the mould may be necessary.

Most analogue hearing aids compress the sound using “automatic gain control” (AGC) so that quiet sounds are amplified until they are loud enough but sounds that are already loud are amplified less to avoid uncomfortable loudness levels.

Digital Hearing Aids

These transcribe the signal from the microphone into “bits” of data which is then fed into a computer chip in the hearing aid to allow precise processing of sound and adjustment to individual needs.  Different settings are available for different listening conditions and such aids can adjust themselves automatically to different sound environments.

Often, they are able to reduce steady background noise to enhance listening, although it can still be difficult to pick up out a single voice from ambient sound in a way that a normally functioning ear is able to do.

It is possible that wearing bilateral aids or hearing aids with twin microphones may be beneficial in noisy situations, with the dual microphones enhancing awareness of sound all around.

Some digital hearing aids are able to use acoustic feedback suppression, or feedback cancellation, to reduce the background whistling, which can otherwise be a problem due to feedback.

Many digital hearing aids will have a wide dynamic range compression which can be individually programmed and can also be self-adjusting.  This often means that the initial fitting time is greater for such aids.  Digital aids, like analogue aids, are available as “behind the ear”, “in the ear” or “in the canal” models and are not necessarily smaller.

Digital and analogue aids both have a T setting which enable sound to be picked up from a loop system or inductive coupler, rather than relying on amplification of sound directly.  This can be useful in premises equipped with loop devices.  It does require a telecoil to be a part of the aid and may not be present in the very smallest types of aids.