Hearing Loss

Hearing fulfils several purposes: it is essential for verbal communication – not only do we hear words but also the nuances in tone which often determine the exact meaning – and for the acquisition of speech. Additionally, it is required for the perception of sound (e.g. music) and it is useful for orientation, as e.g. an approaching vehicle is often heard and located before it is actually seen.

Hearing impairment affects approximately 10% of the population. Although people of all ages can be affected by a hearing loss, the majority of people with impaired hearing are over 60 years old and their hearing loss is related to the aging process. As a rule the deterioration of hearing ability is not painful and is therefore often not taken seriously.

Figures indicate that one out of seven individuals does not have full hearing and one out of ten hears so poorly that a hearing instrument would help.

The degree of hearing loss varies from person to person

Between the two extremes of hearing well and hearing nothing, there are many degrees of impairment. The terms used to describe the degree of hearing loss are mild, moderate, severe and profound. Most hearing losses are mild to moderate.

What does the degree of hearing loss mean?

• Mild hearing loss: unable to hear soft sounds, difficulty understanding speech clearly in noisy environments.
• Moderate hearing loss: unable to hear soft and moderately loud sounds, considerable difficulty understanding speech, particularly with background noise.
• Severe hearing loss: some loud sounds are audible but communication without a hearing instrument is impossible.
• Profound hearing loss: some extremely loud sounds are audible but communication without a hearing instrument is impossible.

How We Hear

Our two ears act like radar antenna to register acoustic signals coming from multiple directions. The complex structures of each ear process the received signals and pass them to the brain where we interpret our acoustic environment.

Take, for example, the sound of an approaching truck: the nearest ear receives the sound slightly earlier than the other and a little louder. Using the finely processed acoustic information from each ear, the brain has the capacity to calculate the direction of the truck's approach and we also "know" approximately how close it is.
Some of the advantages of two properly functioning ears:

• Excellent sound localization skills
• Much easier speech understanding in noisy situations the richest sound quality
• An accurate judgement of loudness

Functions of the Ear

The ear is a very complex organ comprising three parts: the outer ear, the middle ear and the inner ear. From the inner ear the auditory nerve transmits information to the brain for processing.

The outer ear includes the auricle, the auditory canal and the eardrum. It funnels sounds from the surrounding environment into the hearing system. The auricle helps to gather the sound waves, and the auditory canal then directs them to the eardrum.

The middle ear is an air-filled cavity which contains the smallest bones in the human body - the malleus, incus and stapes. These are connected to the eardrum on one side, and on the other side to a thin membrane-covered opening on the wall of the inner ear. The middle ear is also connected to the throat via the Eustachian tube which keeps the air pressure in the middle ear equal to that of the surrounding environment.

In the inner ear the auditory input is processed by the cochlea, while information affecting balance is processed by the semicircular canals. Along the entire length of the fluid filled cochlea there are tiny hair cells. These hair cells are bent when the fluid is displaced by sound waves passed on by the middle ear bones. This triggers a chemical response which activates the corresponding nerve endings. These then transmit the message to the area of the brain in charge of interpreting auditory input.

Solutions

The right choice of hearing instrument type and technology is determined by the individual hearing loss and anatomical features of the ear. Hearingcare professionals and medical practitioners can advise you on the various possibilities available. The following explanations may be useful to you.

The basics of a hearing instrument

Every hearing instrument has one or more microphones which pick up sound from the environment. This acoustic signal is transformed to an electrical signal; it is amplified and adapted according to the individual hearing loss. The receiver (or "loudspeaker") then reconverts it to an acoustic signal which is directed down the ear canal.

Digital, digitally programmable or analog?

• Digital technology

  Thanks to increasingly small micro-processors, digital technology has been applied to hearing systems. Digital hearing instruments are programmed by a hearingcare professional via a PC. Within the hearing instruments, acoustic signals are transformed at high speed and with great precision into a binary code.This allows much more complex calculations and adjustment of the amplified signal than is possible with analog technology. It gives greater flexibility in providing individualized solutions to hearing loss, and allows the addition of features which give the instruments higher value across a greater number of listening situations.



• Programmable digital technology

  This technology is a combination of analog signal processing and digital programming of the hearing system via a PC. It can be used in various combinations to meet individual needs.



• Analog technology

  Hearing instruments with analog signal processing are not programmed via a PC but are adjusted manually by a hearingcare professional using a fine screwdriver. Individualized settings are only possible to a certain degree since innovations such as multi-microphones, the suppression of background noise and convenient remote control operation cannot be integrated into the solution.

• FM technology

  Noise, reverberation, and distance: Whenever even latest-generation hearing instruments approach the limits of their capabilities, FM technology, combined with hearing instruments, significantly enhances the ability of hearing-impaired people to communicate in the most difficult listening situations. Barriers to clear hearing can be successfully overcome because speech and sound are transmitted directly to the hearing-impaired person's ears, without interfering noise.

• Cochlear implant

  A cochlear implant is an electronic device which is surgically implanted in the inner ear of a person who is profoundly or completely deaf. Unlike hearing aids, the implant does not make sounds louder or clearer. Instead, it stimulates the hearing nerve directly. A cochlear implant will give the hearing-impaired person a sensation of hearing. It is important to understand that it only provides a reduced sense of hearing, not a fully restored hearing sense. Therefore, it takes time, practice and patience to learn how to use a cochlear implant.