Sophia Koh Chapter 15 ~ Communication & Sciences Disorders

Factors influencing impact of hearing loss:

• Individual

• Contextual 

• Technical 

Characteristics of Hearing Loss (HL):

• understanding covos, detecting subtle changes (variations in pitch), communicating in noisy environments

POTENTIAL:

• withdrawal from activities, avoidance of social interactions, loss of confidence 

Acquired hearing loss is possible at:

any age

Decibel (dB):

unit of sound pressure

Sound Pressure Level (SPL):

pressure level of sound (measured in dB)

Hearing Level (HL):

• standardized scale

• accounts for varying ear sensitivity across frequencies 

• Normal Hearing Range: -10 to 15 dB HL

• Hearing loss: > 15 dB HL 

Test battery components for hearing eval:

• comprehensive case history

• otoscopy 

• pure tone audiometry (?) & bone conduction 

• speech audiometry 

• immittance testing (alternations/fluctuations of TM & integrity of nervous system in response to stimuli)

Speech Recognition Threshold (SRT):

• measures the intensity at which speech is audible 50% of the time 

Procedure for SRT:

• Spondees presented (equally stressed 2-syllable words ~ ex. mushroom, baseball) 

• Patient repeats (determined when 50% of words correctly identified) 

• Should correlate w/ pure-tone average (PTA) of 500, 1000, & 2000 Hz 

Word Recognition Score (WRS):

• assesses speech understanding at comfortable loudness level 

Procedure for WRS: 

• Present phonemically balanced word lists 

• Patient repeats words: 

  • Score calculated as percentage of words 

  • Provides info on speech clarity perceptions 

  • Helps in determining amplification needs/rehabilitation strategies 

Pure-Tone Audiometry:

• (procedure we use to determine how sound is traveling through the outer, middle, and inner ear)

• preformed for each ear individually 

• uses audiometer 

• measures different frequencies in Hertz (Hz) 

• measures intensity in decibels (dB) 

• Transducers: 

  • Supra-aural headphones 

  • Insert earphones 

  • Speakers 

  • Bone conduction oscillator 

Pure-Tone Audiometry Procedure:

• conducted in sound-treated booth 

• subject/behavioral test 

• patient responds when tone is heard → hand raising, fairy wands, etc. 

• “masking” used for asymmetrical hearing (introducing noise to the non-test ear during a pure-tone audiogram) 

• air conduction (degree, how severe) 

• bone conduction (what TYPE) 

Bone Conduction Pathway

• alternative route for sound to reach inner ear 

• bypasses outer & middle ear 

• Process: 

  • Sound vibrates bones of the skull 

  • Bony labyrinth set into sympathetic vibration 

• Cochlea responds similarly to air conduction 

• Important for distinguishing types of hearing loss 

Audiometer Frequencies (octave intervals typically tested): 

• 125 Hz

• 250 Hz 

• 500 Hz 

• 1000 Hz 

• 2000 Hz 

• 4000 Hz 

• 8000 Hz 

Mid-octave frequencies often included: 

• 750 Hz 

• 1500 Hz 

• 3000 Hz 

• 6000 Hz 

Audiogram: 

graph displaying hearing sensitivity 

• inverted scale: 

  • vertical axis (dB HL) (lower dB # at top; higher dB # at bottom)

  • horizontal axis (frequencies Hz) (low frequencies on left; high frequencies on right) 

Symbols used for audiogram:

• Air Conduction

  • Right ear: red O

  • Left ear: blue X

• Bone conduction (mastoid):

  • Right ear: Red <

  • Left ear: Blue >

• (Different symbols used when masking is applied)

Threshold of Audibility: 

softest sound detectable 50% of the time (expressed in dB HL) 

• plotted on audiogram for each frequency & ear

Speech Audiometry:

• Assesses: how individuals hear speech stimuli 

• Complements pure-tone audiometry 

• 2 main components:

  • Speech Recognition Threshold (SRT)

  • Word Recognition Score (WRS) 

Importance of Comprehensive Hearing Eval:

• combines objective & subjective measures 

• provides detailed info on:

  • degree & type of hearing loss 

  • impact on speech understanding 

  • potential benefit from amplification 

  • guides treatment & management decisions 

  • essential for developing personalized intervention plans

  • crucial for monitoring hearing changes overtime 

Types of hearing loss:

• conductive 

  • (outer, middle) 

• sensorineural 

  • (inner, auditory nerve) 

• mixed 

Conductive Hearing Loss:

• impairment in air conduction

• bone conduction is always w/ in norm. limits (WNL) 

Causes of conductive hearing loss: Outer Ear

• Occulsion of the external auditory canal:

  • Ear wax buildup 

  • Debris from infection

• Tumors, burns, congenital partial/complete closure

Causes of Conductive Hearing Loss: Middle Ear

• Otitis media (middle ear infection)

  • often in childhood

• Other causes:

  • fluid formation acting as a sound barrier, thickening/destruction of the tympanic membrane, damage to ossicular chain, tumors, trauma, Chronic Eustachian tube dysfunction

Treatment for Conductive Hearing Loss:

• Medical intervention

  • Myringotomy for Chronic Eustachian tube Dysfunction

  • Prompt treatment for otitis media

• Audiologic intervention:

  • Indicated for prolonged treatment of hearing loss 

  • Hearing aids 

Audiogram Interpretation for Conductive hearing loss:

• air conduction thresholds elevated

• bone conduction thresholds within normal range

• significant air-bone gap

• (suggests issues in outer or middle ear)

Sensorineural Hearing Loss:

damage to inner ear (cochlea) or auditory nerve

• Characteristics:

  • mild to total hearing loss 

  • No air-bone gap 

  • Poorer Word Recognition Thresholds (WRTs) 

Causes of sensorineural hearing loss (COCHLEAR): 

• Prenatal causes:

  • maternal alcohol/drug abuse 

• Perinatal causes 

  • birth complications (umbilical strangulations) 

• Postnatal causes

  • prolonged otitis media 

  • aging process

Causes of sensorineural hearing loss (AUDITORY NERVE): 

• Acoustic neuroma

  • tumor on vestibular branch of auditory nerve 

  • usually unilateral (affects 1 ear)

• Symptoms 

  • Tinnitus (ringing/roaring sounds)

  • progressive hearing loss 

Audiogram features for sensorineural hearing loss: 

• both air & bone conduction thresholds elevated 

• no significant air-bone gap 

• often shows sloping configuration 

• (indicates cochlear or auditory nerve damage)

Mixed Hearing Loss:

combination of conductive & sensorineural hearing loss 

Audiogram for mixed hearing loss:

• air & bone conduction thresholds outside normal limits (elevated) 

• air-bone gap present, but bone conduction also affected 

• (suggests combo of conductive & sensorineural issues)

Mixed hearing loss measurement & interpretation:

Measurement: 

• sensorineural component 

• air-bone gap (ABG) - difference between air & bone conduction thresholds 

Interpretation: 

• smaller ABG 

• larger ABG 

Audiogram Interpretation: Normal Hearing

• Thresholds below 15 dB HL at all frequencies

• No significant difference between air & bone conduction

• indicates optimal hearing sensitivity

Impact of Hearing Loss on Speech Discrimination:

• Word Recognition Thresholds (WRTs)

  • Normal: excellent

  • Conductive: generally good

  • Sensorineural: poorer, often correlated with degree of loss

• Implications:

  • Conductive: may benefit from amplification (signal just needs amplification)

  • Sensorineural: may have persistent speech discrimination difficulties even w/ amplification (signal itself is degraded)

Importance of early intervention:

• language development in children

• improves quality of life & communication in adults

Ex. of reading audiograms:

• “Within normal limits sloping to moderately-severe sensorineural hearing loss.” 

• “Mild conductive hearing loss.” 

Degree of Hearing Loss Chart:

• 0-15 normal 

• 16-25 slight 

• 26-40 mild 

• 41-55 moderate 

• 56-70 moderately-severe 

• 71-90 severe

• 91-120 profound