Types of Hearing Loss and Audiology Stuff Flashcards
Sensorineural Hearing Loss
is one resulting from dysfunction of the inner ear, the cochlea, the nerve that transmits the impulses from the cochlea to the hearing centre in the brain or damage in the brain. The most common reason for sensorineural hearing impairment is damage to the hair cells in the cochlea.
Conductive Hearing Loss
present when the sound is not reaching the inner ear, the cochlea. This can be due to external ear canal malformation, dysfunction of the eardrum or malfunction of the bones of the middle ear.
Mixed Hearing Loss
A combination of the two types discussed above. Chronic ear infection that is fairly common diagnosis could result in a defect ear drum and/or middle ear `ossicle damages.
Degrees of Hearing Loss
Normal –10 to 15 Slight 16 to 25 Mild 26 to 40 Moderate 41 to 55 Moderately severe 56 to 70 Severe 71 to 90 Profound 91+
Relationship of degree of long term hearing loss to psychosocial impact and functional needs - normal hearing (-10 to 15 db)
Children have better hearing sensitivity than the accepted normal range for adults. A child with hearing sensitivity in the -10 to 15 db will detect the complete speech signal even at soft conversation levels.
However, good hearing does not guarantee good ability to discriminate speech in the presence of background noise.
Relationship of degree of long term hearing loss to psychosocial impact and functional needs- slight (16 to 25 db)
May have difficulty hearing faint or distant speech. At 15 db student can miss up to 10% of speech signal when teacher is at a distance greater than 3 feet and when classroom is noisy, especially in the elementary grades when verbal instruction predominates.
Relationship of degree of long term hearing loss to psychosocial impact and functional needs - mild (26 to 40 db)
At 30 db can miss 25-40 % of speech signal. The degree of difficulty experienced in school will depend upon the noise level in classroom, distance from the teacher and the configuration of the hearing loss. Without amplification the child with 35-40 db loss may miss at least 50% of class discussions, especially when voices are faint or speaker is not in line of vision. Will miss consonants, especially when a high frequency hearing loss is present.
Relationship of degree of long term hearing loss to psychosocial impact and functional needs - moderate (41 to 55 db)
Understands conversational speech at a distance of 3 to 5 feet (face to face) only if structure and vocabulary controlled without amplification the amount of speech signal missed can be 50 % to 75% with 40 db loss and 80% to 100% with 50 db loss. Is
Iikely to have delayed or defective syntax, limited vocabulary, imperfect speech production and an atonal voice quality.
Relationship of degree of long term hearing loss to psychosocial impact and functional needs - moderate to serve (56 to 70 db)
Without amplification conversation must be very loud to be understood. A 55 db loss can cause the child to miss up to 100% of speech information. Will have marked difficulty in school situations requiring verbal communication in both one to one and group situations. Delayed language, syntax, reduced speech intelligibility, and atonal voice quality likely.
Relationship of degree of long term hearing loss to psychosocial impact and functional needs - severe ( 71 to 90 db)
Without amplification may hear loud voices about one foot from ear. When amplified optimally, children with hearing ability of 90 db or better should be able to identity environmental sounds and detect all sounds of speech. If loss is of prelingual onset, oral language and speech may not develop spontaneously or will be severely delayed. If hearing loss is of recent onset speech is likely to deteriorate with quality becoming atonal.
Relationship of degree of long term hearing loss to psychosocial impact and functional needs - profound (91 db or more)
Aware of vibrations more than tonal pattern. Many rely on vision rather than hearing as primary avenue for communication and learning. Detection of speech sounds dependent upon loss configuration and use of amplification. Speech and language will not develop spontaneously and is likely to deteriorate rapidly if hearing loss is of recent onset.
Relationship of degree of long term hearing loss to psychosocial impact and functional needs - unilateral (one normal hearing ear and one ear with at least a permanent mild hearing loss)
May have difficulty hearing faint or distant speech. Usually has difficulty localizing sounds and voices. Unilateral listener will have greater difficulty understanding speech when environment is noisy and/or reverberant. Difficulty detecting or understanding soft speech from side of bad ear, especially in a group discussion.
Pure Tone Testing
Provides information about the faintest tones a person hears at selected low to high pitch (frequencies).
Bilateral versus unilateral
Bilateral means hearing loss in both ears. Unilateral means hearing loss in one ear.
Symmetrical versus asymmetrical
Symmetrical means the degree and configuration of hearing loss are the same in each ear. Asymmetrical means degree and configuration of hearing loss are different in each ear.
