CC3 - Types and Degrees of Hearing Loss

Type of Hearing Loss

Determined by comparing air conduction thresholds to bone conduction thresholds for each ear independently

Four types of hearing loss

• Conductive

• Sensorineural

• Mixed

• Auditory processing disorders

Sudden HL

Rapid onset

Gradual HL

Hearing loss occurs in small degrees

Temporary HL

Short duration/reversible

Permanent HL

Not reversible

Progressive HL

Hearing loss will advance in degrees

AU

Both ears

AS

Left ear

AD

Right ear

Monaurally

1 ear

Binaural

Both ears

Flat

Less than a 5dB rise/fall per octave

Gradually sloping

5-12 dB decrease per octave

Sharply sloping

13 or more dB decrease per octave

Rising

Low frequency are poorer than high frequency

Noice notch

normal haring until 4000 Hz then a decrease

Cookie Bite Audiogram

L Corner Audiogram

Hearing loss is described in terms of

• type

• degree

• symmetry

• configuration

• time of onset (time course)

Normal Audiogram

Conductive hearing loss (CHL)

• Involves obstruction of outer and middle ear mechanisms

• Characterized by bone conduction thresholds within normal range (0-20 dB HL) with higher air conduction thresholds (greater than 20 dB HL)

• Can cause occlusion effect = person usually speaks in a quieter voice than normal because they perceive it louder than what it actually is

  • Opposite of Lombard effect

• Audiogram is characterized by flat configuration of low frequency loss and patient may have occasional tinnitus

CHL

Loss can be overcome if the signal is loud enough because there is no problem with the cochlea

• If amplified = speech discrimination is not impaired

Paracusis Willisii

Ability to hear better in noisy environments

Unilateral Conductive Hearing Loss

Bilateral Conductive

Sensorineural Hearing Loss (SNHL)

• Involves the pathology of the inner ear

• Two types

  • Sensory hearing loss = result of damage to the cochlea

  • Neural loss = damage to 8th nerve

• Audiogram = sloping air conduction and bone conduction thresholds are essentially equal (i.e., within 10 dB)

• All thresholds outside the normal range

• Continued reduction of speech recognition ability even with adequate amplification

• May have tinnitus, especially with Meniere’s

• Recruitment = cochlear phenomenon where there is a nonlinear increase in loudness growth, wherein loudness grows rapidly at intensity levels just above thresholds but may grow normally at higher levels

  • Indication of retrocochlear pathology

• May have diplacusis = where one tone sounds like 2 different pitches in two ears, and is an indication of retrocochlear disease

• Patient will speak excessively loudly since the patient can’t monitor himself

Sensory Hearing Loss

Damage of cochlea

Someone who has sensory hearing loss (SNHL) presents with

• Recruitment

• Reduction in frequency resolution (impacts speech understanding)

• Reduced dynamic range

• Word recognition ability is reduced

Neural Hearing Loss

Damage of VN 8 (vestibulocochlear)

Someone who has neural hearing loss (SNHL) presents with

• Word recognition ability is poorer than expected based on hearing loss severity

• Speech recognition declines with increases in intensity (rollover phenomenon)

• Auditory adaptation occurs

Unilateral Sensorineural Hearing Loss

Unilateral SNHL - Meniere’s

Mixed Hearing Loss

• Result of both OE/ME and IE pathologies

• Combination of both CHL and SNHL

• Characterized by bone conduction thresholds outside normal hearing range, with air conduction thresholds poorer than bone conduction thresholds

• The difference between air and bone conduction thresholds is known as the air-bone gap (ABG)

• Reflects degree of conductive component contributing to overall hearing loss

Bilateral Mixed

Degree of Hearing Loss

• Adults range from mild to severe-profound

• Children range from slight to profound

• Normal = -10 to 15 dB

  • Patient hears almost everything well, but may struggle in less than ideal situations (i.e., noise)

• Slight = 16 to 25 dB (only in children)

• Mild = 26 to 40 dB

  • Patient may have difficulty understanding speech if it is faint or distant

  • #1 problem in schools

• Moderate = 41 to 55 dB

  • Listening is strain and he/she often asks for repetition

• Moderately-severe = 56 to 70 dB

• Severe = 71 to 90 dB

  • Patient may hear loud voice about 1 foot away from ear

• Profound = 91 dB+

  • Patients will not rely on hearing as primary use of communication

Normal HL

-10 to 15 dB

Slight HL

16 to 25 dB

Mild

26 to 40 dB

Moderate

41 to 55 dB

Moderatley Severe

56 to 70 dB

Severe

71 to 90 dB

Profound

91+ dB

Symmetry

How much right and left ears mirror one another

Configuration

Pattern that describes relationship of low-frequency hearing to high frequency hearing

Asymmetrical Loss

When one hear has loss and other is normal or one ear is much more severe than other

Noise Exposure

Sensorineural notch at 3000 or 4000 Hz

ME Effusions (fluid in ME space)

Rising conductive loss reflects stiffness tilt

Ossicular discontinuity, ME tumor and thickened TM

Sloping conductive loss reflects mass tilt

Otosclerosis

Hardening at footplate of the stapes – Carhart notch

Presbycusis

Age related high frequency hearing loss

Noise Induced

Rising Conductive Loss

Ossicular Discontinuity

Otosclerosis

Carhart’s Notch

Presbycusis

Time of Onset (time course)

• Time of onset or time course deals with how long the patient has been experiencing problems

  • Describe hearing loss as progressive versus stable

  • Describe it as acute, sudden, or gradual

Malingering

• May report functional hearing loss

• Also referred to as non-organic hearing loss (NOHL), pseudohypacusis, or psychogenic hearing loss

• Intra- and intertest discrepancies that cannot be accounted for

• EX: Poor SRT-PTA agreement

• Should not exceed 6dB

• Patient may only repeat half of the spondee

• Absence of shadow curve (greater than 60 dB difference between right and left ears for unmasked air conduction thresholds)

• Bone conduction thresholds will be poorer than air conduction thresholds

• Most common in boys who are young school age

• Malinger to gain attention or to compensate for poor academic performance

• Difficult to explain to the parent, so it may be important to ask if anything else was going on when the loss was first noticed

  • Divorce, a new baby, or a major move

• Adults = secondary financial gain

• Objective physiologic levels = Stenger test

• Two pure tones of equal intensity are presented bilaterally; whichever ear sounds louder, that is the one that responds, and the other ear acts dead.

Pseudohypacusis

Inconsistency in audiometric data

• Mainly seen in children

Psychogenic hearing loss

Seen suddenly in girls between the ages of 8 and 12

• Loss does not affect school ability or vocal quality

Impact of hearing loss on communication depends on

• Degree of sensitivity loss

• Audiometric configuration

• Type of hearing loss

• Degree and nature of speech perception deficits

Auditory Perception

• Communication depends on the quality of auditory perception of

• Segmentals

• Suprasegmentals

• Begins before birth

• After birth, the process of selective listening extends to speech stimuli within a few weeks

Segmentals

• Intensity

• Frequency

• Duration

Suprasegmentals

• rate

• rhythm

• intonation

Sound class and relative power in speech

Suprasegmentals

Convey important information, primarily in low frequencies through cues associated with fundamental frequency (e.g., pitch falls or rises at end of utterance)

True or False: Every sound is composed of its own specific acoustical energy (due to the resonance of the vocal tract)

True

True or False: Every sound also has its own relative power (energy, intensity)

True

True or False: Voicing, nasality, duration, and place of articulation are NOT key distinctive features found in speech

False

Perception implies understanding and comprehension NOT

Just reception of speech

Detection

Do you hear the sound, yes or no?

Discrimination

Do the 2 sounds sound the same or different?

Identification

What is that sound?

Attention

Degree/ quality of listener’s attention matters

Memory

Ability to retain or store verbal information

Closure

Bringing speech elements together into a meaningful whole

Comprehension

What does that mean?

Example of Perception with HL

Speech Banana

True or False: Do not assume a slight loss will not impact their speech/ language skills, particularly in academic setting

True

Slight Loss (16-25 dB)

• Perceived as if index fingers are in ears

• Difficulty hearing faint or distant speech

• Child can miss up to 10% of the speech signal at a distance of greater than 3 feet

• This is amplified in background noise (imagine a classroom)

  • Preferential seating

  • FM System

Mild Loss (26-40 dB)

• Greater listening difficulties than “plugged-ear” hearing loss

  • Can hear but misses parts of speech

  • Leads to a misunderstanding of the message

30 dB Loss

Child can miss up to 25-40% of speech signal

40 dB Loss

A child misses up to 50% of the speech signal

• Will frequently have difficulty learning early reading skills

  • Sound/letter association

Moderate (41-55 dB) HL

Associated with frequent misunderstanding of signal

50 dB HL

A child may miss up to 80% of the speech signal

• Without early amplification, a child will likely be language delayed with impaired syntax, limited vocabulary, disordered speech sound production, and flat vocal quality

• Even with proper amplification, but with sufficient background noise = child will miss much of what is being said, as the signal-to-noise ratio is corrupted

Perception with Severe HL

• Perception of sound is very limited

• Earlier child wears amplification consistently with parents/caregivers providing language models in activities of daily living and/or intensive language intervention (verbal or sign or both) increases chances that speech, language, and learning will develop at a relatively normal rate

• The ability of the brain to interpret sounds as meaningful input is determined by the patient’s individual ability and intensive intervention prior to 6 months of age

• Hearing loss greater than 70 dB = candidates for cochlear implant (CI)

• 90 dB+ hearing loss = won’t perceive most speech sounds with a traditional hearing aid

Importance of Modeling

• Modeling language will be crucial for language development since children imitate what they hear

  • Amount this is done will affect how much and how well the child speaks

True or False: Not Important for a child to look at the parent who is talking to learn how to begin to read lips as a compensatory strategy

False

True or False: You should control distance between speaker and listener by being no more than 5 feet away, especially important in young children

True

Suggestions for parents

• Talk slightly louder than normal

• Minimize the background noise

• Use language stimulation strategies:

  • Parallel and self talk during activities

  • Expansions of what child says

  • Expatiations by adding new information

  • Use new words

  • Provide adult speech model for speech sound development

• Read aloud together

  • Should begin when the child is less than a year old

  • Can help promote bonding and language growth

• Work with an SLP