- Auditory Neuropathy/Dys-synchrony (AN/AD); also known as Auditory Neuropathy (AN) and more recently Auditory Neuropathy Spectrum Disorder (ANSD). A distinguishing characteristic of AN/AD is the presence of auditory responses associated with normal function of the outer hair cells of the cochlea and poor neural synchrony of the auditory (VIIIth cranial) nerve. (Berlin, Hood and Rose, 2001).
Symptoms that characterize people with AN/AD:
People with AN/AD have great difficulty understanding simple sentences in competing noise-despite the fact that they can understand some words or sentences in quiet. Learning speech and language through the auditory channel exclusively is very difficult for patients with AN/AD. This is most likely due to difficulty in achieving a clear and consistent auditory signal in a dys-synchronous auditory system. Transmission of auditory information to the cortex depends on the synchronous (simultaneous) firing of many neurons to move the signal along the neural pathway.
- An Otoacoustic Emission (OAE) is a sound which is generated from within the inner ear. An OAE test measures an acoustic response that is produced by the inner ear (cochlea), which in essence bounces back out of the ear in response to a sound stimulus. The test is performed by placing a small probe that contains a microphone and speaker into the infant's ear. As the infant rests quietly, sounds are generated in the probe and responses that come back from the cochlea are recorded. Once the cochlea processes the sound, an electrical stimulus is sent to the brainstem. In addition, there is a second and separate sound that does not travel up the nerve, but comes back out into the infant's ear canal. This "byproduct" is the otoacoustic emission. The emission is then recorded with the microphone probe and represented pictorially on a computer screen. The audiologist can determine which sounds yielded a response/emission and the strength of those responses. If there is an emission present for those sounds that are critical to speech comprehension, then the infant has "passed" the hearing screen.
A newborn’s OAEs are measured during the newborn hearing screening, and typically an ABR is not used in the initial screen. AN/AD can go undiagnosed because of the presence of OAEs at birth. AN/AD is diagnosed via an OAE and ABR test since the common trend is present OAEs, but no response on the ABR. Eventually the OAEs tend to disappear in AN/AD patients.
- Auditory Brainstem Response (ABR) audiometry is a screening test to monitor for hearing loss or deafness. It is a method employed to assess the functions of the ears, cranial nerves, and various brain functions of the lower part of the auditory system, prior to the child developing to the point of describing a possible hearing problem.
A certified clinical audiologist will usually perform and interpret the auditory brainstem response test. The test is relatively simple—generally taking less than 30 minutes—and is non-invasive and painless. Auditory brainstem response is measured by attaching electrodes to the ear lobes and scalp.
During the test, a series of clicking noises are delivered to the ear through earphones, which stimulate the hearing nerves and brain. The brainstem emits waves, or brainstem auditory evoked potentials (BAEPs), in response to the clicks, and which are sensed by the electrodes. The BAEPs, and any changes that occur to them, are then recorded and graphed.
- Cortical Auditory evoked potentials (CAEP) can be used to objectively assess hearing sensitivity, central auditory processing, and neural encoding of speech sounds up to the level of the auditory cortex. Evoked potentials have been of interest to clinicians and researchers in the cochlear implant field for a long time because of their potential for objectively predicting cochlear implant outcomes, as well as improving candidacy determination, and implant programming. Neural response telemetry and intra-operative electrical auditory brainstem recording have been routinely performed by implant programs for many years. Recently, there has been great interest in potential clinical applications of cortical auditory evoked potentials in the implant field. Research and clinical applications are reviewed and case studies are presented that illustrate clinical applications of cortical evoked potentials in children before and after implantation.
- Cochlear Implant (CI) is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. The cochlear implant is often referred to as a bionic ear. Unlike hearing aids, the cochlear implant does not amplify sound, but works by directly stimulating any functioning auditory nerves inside the cochlea with electric field stimulated through an electric impulse. External components of the cochlear implant include a microphone, speech processor and an RF transmitter. Similarly an RF receiver is implanted beneath the skull’s skin. The transmitter has a piece of magnet by which it attaches to another magnet placed beside the receiver. When the receiver gets a signal, it will be transmitted to the implanted electrodes in the cochlea. The speech processor allows an individual to adjust the sound level of sensitivity.
An implant does not restore normal hearing. Instead, it can give a deaf person a useful representation of sounds in the environment and help him or her to understand speech.
- Auditory Oral Therapy - The auditory-oral approach is a method in which children learn to use whatever hearing they have, in combination with lipreading and contextual cues (speechreading) to understand and use spoken language. The goal is to give the deaf individual the necessary spoken language skills to be mainstreamed educationally and to function independently in the hearing world. This approach facilitates the development of reading and writing skills because proficiency in the English language is critical to developing good reading ability, and competence in reading is critical to learning in all academic areas. Small self-contained classrooms coupled with daily individualized instruction provide the intense early intervention needed in this approach. Teachers in these programs are highly trained and provide spoken language instruction throughout the day in all classroom activities. This is full-time therapy and education.
· Auditory Verbal (AV) Therapy is a method for teaching deaf children to listen and speak using their residual hearing in addition to the constant use of amplification devices such as hearing aids, FM devices, and cochlear implants. Auditory-verbal therapy emphasizes speech and listening, discouraging reliance on visual communication such as lip reading or Sign Languages (American Sign Language, British Sign Language, etc.).Auditory verbal therapy is used in the United States under the theory that it enables deaf and hearing impaired children to participate more fully in mainstream school and hearing society. Published research suggests its efficacy in enabling deaf children to learn to listen and talk, however such research has not yet included control groups or randomized controls, so it is not possible to conclude whether auditory-verbal therapy was the cause of the progress seen in these children (Goldberg & Felexer 2001, Rhoades & Chisholm 2001, Hogan et al. 2008)[2][3].
