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A choice of therapy is only valid when it is correctly implemented. Therefore selecting a therapy should take into account the proposed method, acceptance by the patient and their family, the care put into place by the medical team (doctor, ENT, speech and language therapist...). One of the main criteria for successful auditory rehabilitation is early intervention.
In infants and children, partial or profound hearing loss has systematic repercussions on at least one constituent of spoken language. Healthy auditory function is required for the development of speech. Immersion into the world of sound allows infants to develop phonological, lexical and syntaxic abilities as well as accessing one or more spoken languages.
In adults, in the general case of a progressive hearing loss (such as presbycusis), it is important not to wait too long before treatment. The period preceding the accentuation of the hearing loss should be used to reduce the ongoing effects as much as possible. When it cannot be cured, a deficit can be compensated for. This chapter will therefore focus on two main points: substitution of sound via external and implanted hearing devices, and functional substitution carried out by speech and language therapists.
Indications and medical prescriptions
Depending on the etiology of the hearing loss and its repercussions, the specialized medical team can select conventional hearing aids (air conduction) or those that are implanted into the skull (bone conduction), the middle ear (mechanical amplification) or the cochlea (electrical stimulation).
Ear, Nose and Throat specialist (ENT)
A diagnosis of hearing loss is carried out by an ENT specialist and no other doctor, after a general examination and more specific examinations of the middle ear, with at least one audiogram. From there, a prescription for hearing aids is only valid, in theory, when delivered by an ENT specialist as his colleagues are not trained to do so. Once the diagnosis of hearing loss has been determined, the etiology must be found. The examination and the audiogram can lead to further tests (such as an MRI). Once the clinical picture has been well defined, the best solution for the patient is suggested and can be either surgical, medical or via the use of hearing devices. The choice of therapy is undertaken with the patient after outlining the pros and cons of each option.
In the case of conventional hearing aids, after receiving a script from the ENT specialist, the hearing impaired patient sees an audiologist. In a first visit, hearing loss is evaluated using specific tests relevant to hearing aid fitting (see the section "Audiometry"). After these initial tests, a hearing aid is selected and fit to each individual patient. The audiologist is required to test and control the benefit bestowed by the hearing aid and actively participates in rehabilitation using the device. Trialling the hearing aid is essential before it is adopted in the long term. Finally, the audiologist ensures the patient follow-up, controls the hearing aids and checks the patient's hearing ability in combination with the prescribing doctor and, if required, the speech and language therapist.
Speech and language therapy
Speech and language therapists provide a hearing impaired listener with the required elements for good speech comprehension. Hearing is not enough: understanding the sound signal can be difficult for listeners who have lacked certain acoustic information for a long period of time. The sound that is provided by the hearing aids does not always enable the listener to understand what is being said. In fact, the new sound can sometimes be classified as 'noise' and ignored. Language is made up of linguistic signals which link concepts to acoustic images. Speech and language therapy aims to work on these points to help a hearing impaired listener make sense of the auditory world. In some cases, speech or lip reading can be used to reinforce the message.
The auditory system can not be returned to perfect function via a hearing aid. At best, the aim is to optimise the functionality of a sound to residual hearing. Hearing aids are less efficient when no residual hearing is present. Additionally, despite the existance of directional microphones and complicated algorithms for sound processing, understanding speech in noise remains limited.