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Audiology 101: an Introduction to Audiology for Nonaudiologists Terry Foust, Aud, FAAA, CC-SLP/A; & Jeff Hoffman, MS, CCC-A

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Audiology 101: an Introduction to Audiology for Nonaudiologists Terry Foust, Aud, FAAA, CC-SLP/A; & Jeff Hoffman, MS, CCC-A NATIONALA RESOURCE CENTER GUIDE FOR FOR EARLY HEARING HEARING ASSESSMENT DETECTION & & MANAGEMENT INTERVENTION Chapter 5 Audiology 101: An Introduction to Audiology for Nonaudiologists Terry Foust, AuD, FAAA, CC-SLP/A; & Jeff Hoffman, MS, CCC-A Parents of young Introduction What is an audiologist? children who are arents of young children who are An audiologist is a specialist in hearing identified as deaf or hard identified as deaf or hard of hearing and balance who typically works in of hearing (DHH) are P(DHH) are suddenly thrust into a either a medical, private practice, or an suddenly thrust into a world of new concepts and a bewildering educational setting. The primary roles of world of new concepts array of terms. What’s a decibel or hertz? an audiologist include the identification and a bewildering array What does sensorineural mean? Is a and assessment of hearing and balance moderate hearing loss one to be concerned problems, the habilitation or rehabilitation of terms. about, since it’s only moderate? What’s of hearing and balance problems, and the a tympanogram or a cochlear implant? prevention of hearing loss. When working These are just a few of the many questions with infants and young children, the that a parent whose child has been primary focus of audiology is hearing. identified as DHH may have. In addition to parents, questions also arise from Audiologists are licensed by the state in professionals and paraprofessionals who which they practice and may be members work in the field of early hearing detection of the American Speech-Language- and intervention (EHDI) and are not Hearing Association (ASHA), American audiologists. The purpose of this chapter Academy of Audiology (AAA), Academy is to provide basic answers to these and of Doctors of Audiology (ADA), or the other important questions about the field Educational Audiology Association of audiology. (EAA). Some audiologists hold the eBook Chapter 5 • An IntroductioneBook to Audiology Chapter for 5 • Nonaudiologists Audiology 101: • 5-1 A RESOURCE GUIDE FOR EARLY HEARING DETECTION & INTERVENTION American Board of Audiology’s Pediatric and fiber tissue. It is attached to the wall of Audiology Specialty Certification. Others the ear canal and also to one of the bones may hold the ASHA Certificate of Clinical of the middle ear. The eardrum seals the Competence in Audiology (CCC-A). middle ear from the environment. Sound vibrates the eardrum and is changed to Several online search tools are available to mechanical energy. find an audiologist: The middle ear is a hollow space that • Early Hearing Detection and is separated from the ear canal by the Intervention Pediatric Links to eardrum and contains the three smallest Services (EHDI-PALS) bones in the body. Sounds travel through • Early Hearing Detection and the outer ear and are transferred to the Intervention (EHDI) program, also inner ear by these bones (ossicles). The known as the Newborn Hearing three bones are the hammer (malleus), Screening Program, in each state anvil (incus), and stirrup (stapes). They • ASHA are connected by ligaments, and two of • AAA the bones have tiny muscles attached. The shape and arrangement of the ossicles What are the parts of the ear? increases the strength of the mechanical energy. When loud sounds are present, the tiny muscles contract and reduce the A basic understanding of the parts of strength of those sounds. This helps protect A basic understanding the auditory system and how they work the ear from damage due to loud sounds. of the parts of the is helpful to understanding the different auditory system and types of hearing loss. There are four main The Eustachian tube is also part of how they work is helpful parts of the auditory system: the middle ear system and connects the middle ear space to the back of to understanding • Outer ear the throat. The Eustachian tube is the different types of • Middle ear normally closed but opens periodically hearing loss. • Inner ear to keep the air pressure in the middle • Central auditory system ear space the same as the surrounding environment. An example of the Each part plays an important role in Eustachian tube working occurs when transferring and processing sound, so that a yawn or a swallow “unstuffs the ears” the brain can recognize and interpret what a particular sound means. The outer ear consists of three major parts: Figure 1 Anatomy of the Auditory • Pinna • Ear canal System • Eardrum (tympanic membrane) The pinna is the part of the ear that we see and contributes slightly to locating a sound. The ear canal, which is about an inch long and S-shaped, channels sound toward the eardrum. The ear canal produces earwax which helps to clean the ear canal of debris. The last part of the outer ear is the eardrum which is the boundary between the outer and the middle ears. The eardrum is a very thin membrane, consisting of layers of skin eBook Chapter 5 • Audiology 101: • 5-2 NATIONAL CENTER FOR HEARING ASSESSMENT & MANAGEMENT when flying in an airplane. Sometimes What are the types of If a child is born with a the tissues of the Eustachian tube significant malformation become swollen from a cold or hearing loss? of the outer and/or upper respiratory infection, and it middle ear that prevents doesn’t open and close well—causing Hearing losses can be categorized by when problems in the middle ear. It’s they occur. A hearing loss that is present at or reduces the sounds possible for infection to spread from birth is called a congenital hearing loss. But being conducted to the the nose and throat area through the hearing loss can and does occur at any time inner ear, surgery may Eustachian tube to the middle ear, and can be called later-onset or acquired. If be possible. The child’s which is one of the causes of middle a hearing loss continues to get worse, it is hearing ability may or ear infections. called a progressive hearing loss. may not improve after The third part of the auditory system is the One of the ways that an audiologist surgical treatment. inner ear. The inner ear has two sections: describes a hearing loss is by how many one that is responsible for balance and ears are involved. If a hearing loss is only the other for hearing. The hearing part of in one ear, the loss is called a unilateral the inner ear is the cochlea. The cochlea (one-sided) hearing loss. If there is hearing is a snail-shaped space in the skull that loss in both ears, it is described as a contains very tiny structures that convert bilateral (two-sided) hearing loss. mechanical energy into electrical impulses needed for the nervous or central auditory The different types of hearing loss are system. The cochlea is divided by tissue primarily based on what part of the ear is structures into three channels, each of preventing a sound from being transferred which is filled with fluid. There are many and processed effectively. thousands of tiny hair cells (stereocilia) that are embedded in the tissue that Conductive Hearing Loss divides the three sections. The hair cells bend slightly in response to different kinds A conductive hearing loss occurs because of sounds, depending on where they are problems in the outer and/or middle ear located in the cochlea. When bent, the keep the sound from being “conducted” hair cells create electrical signals that are well. Conductive hearing losses can be then sent to the central auditory nervous either temporary (transient) or permanent. system. Medical treatment of the underlying cause of the temporary conductive hearing loss The last part of the auditory system may result in the hearing returning to consists of the auditory nerve and the normal or near normal. For example, if central auditory system in the brain. The the ear canal is plugged with earwax or an electrical nerve impulses produced in the object of some sort, some hearing loss will cochlea by the hair cells are transmitted occur until the blockage is removed. The and processed along the auditory nerve amount of hearing loss would be similar to that consists of about 25,000 nerve fibers. having an earplug in your ear canal. The signal continues through the brain stem to the auditory cortex of the brain. It At least 80% of children have three or more is in the cortex that sounds are interpreted episodes of ear infections (otitis media) based on experience and association and before 3 years of age (Roberts & Hunter, that meaning is assigned to sounds that 2002). These ear infections can be painful, travel through the outer, middle, and inner and if the middle ear space fills with fluid, ears. a temporary conductive hearing loss can occur. Middle ear infections left untreated Auditory Transduction by Brandon Pletsch can cause some other middle ear problems is an excellent 7-minute animation on that may result in a permanent loss. YouTube about the different structures of the auditory system, how they work, and If a child is born with a significant how each contributes to hearing. malformation of the outer and/or middle eBook Chapter 5 • An Introduction to Audiology for Nonaudiologists • 5-3 A RESOURCE GUIDE FOR EARLY HEARING DETECTION & INTERVENTION ear that prevents or reduces the sounds How often does hearing loss being conducted to the inner ear, surgery may be possible. The child’s hearing ability occur in young children? may or may not improve after surgical treatment. Many children have a temporary conductive hearing loss due to ear Sensorineural (or Sensory) Hearing Loss infections, but how many have a permanent hearing loss? Each year, state A sensorineural (or sensory) hearing loss EHDI programs send the results of their from problems in the cochlea or inner newborn hearing screening program ear is almost always permanent.
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