Audiology Chapter 3: Human Ear, Hearing Loss, and Pure-Tone Hearing Tests

Vocabulary flashcards covering key terms from Chapter 3, including ear anatomy, types of hearing loss, test procedures, calibration, and audiometric concepts.

Outer Ear

The portion of the auditory system consisting of the pinna and ear canal; gathers sound waves toward the tympanic membrane.

Middle Ear

Air-filled cavity containing the tympanic membrane and ossicular chain that converts acoustic energy into mechanical vibrations.

Inner Ear

Fluid-filled cochlea and vestibular organs where mechanical energy becomes hydromechanical and then electrical nerve impulses.

Conductive Mechanism

The outer and middle ears, responsible for conducting sound to the inner ear.

Sensory/Neural Mechanism

The inner ear, auditory nerve, and central pathways that transduce and transmit electrical signals to the brain.

Tympanic Membrane (TM)

The eardrum; vibrates in response to sound and initiates mechanical energy transfer through the ossicles.

Ossicular Chain

The three middle-ear bones (malleus, incus, stapes) that transmit vibrations from the TM to the cochlea.

Cochlea

Spiral inner-ear structure where fluid motion stimulates hair cells, creating neural impulses.

Conductive Hearing Loss

Hearing loss due to outer or middle ear pathology; abnormal air-conduction thresholds with normal bone-conduction thresholds.

Sensorineural Hearing Loss

Loss caused by inner-ear or auditory-nerve damage; air- and bone-conduction thresholds are equal and abnormal.

Mixed Hearing Loss

Combination of conductive and sensorineural components, producing both elevated AC and BC thresholds with an air-bone gap.

Central Hearing Loss

Reduced auditory comprehension from central auditory processing deficits despite normal peripheral thresholds.

Nonorganic Hearing Loss

Behavioral test results suggest hearing loss, but no physiological evidence supports it.

Malingering

Deliberate feigning of hearing loss for personal gain.

Psychogenic Hearing Loss

Apparent hearing deficit linked to psychological factors rather than organic ear pathology.

Attenuation

A decrease in sound intensity (loudness).

Case History

Detailed patient interview collecting medical and auditory information prior to testing.

Otoscopy

Visual inspection of the ear canal and eardrum using an otoscope.

Tuning Fork Test

Diagnostic use of vibrating forks to differentiate conductive vs. sensorineural loss pre-audiometer era.

Weber Test

Midline bone-conduction test for sound lateralization; tone lateralizes to better ear in SNHL and to poorer ear in conductive loss.

Rinne Test

Compares perception of air- versus bone-conduction; louder by air in normal/SNHL, louder by bone in conductive loss.

Pure-Tone Audiometry

Measurement of hearing thresholds for single-frequency tones via air and bone conduction.

Threshold (Audiology)

Lowest intensity level at which a tone is heard 50% of the time.

Air Conduction (AC)

Testing pathway using earphones that assesses outer, middle, inner, and central auditory systems.

Bone Conduction (BC)

Testing pathway using a skull vibrator that bypasses the outer/middle ear to evaluate inner ear and beyond.

Speech Audiometry

Tests determining speech detection and recognition abilities.

Audiogram

Graph plotting hearing thresholds (dB HL) across frequencies (Hz) for each ear.

Air-Bone Gap (ABG)

Difference between AC and BC thresholds; indicates conductive component when ≥15 dB.

Electroacoustic Calibration

Annual electronic verification of audiometer output levels, distortion, and linearity with sound-level meter and couplers.

Bioacoustic Calibration

Daily listening check comparing clinician’s thresholds to previous results for equipment integrity.

Sound Booth

Prefabricated, sound-treated room used to attenuate ambient noise during testing.

Insert Earphones

Disposable foam-tip transducers inserted into the ear canal; improve comfort, hygiene, and reduce need for masking.

Supra-Aural Headphones

Standard ear-cushion transducers that rest on the pinna; require careful placement to avoid ear-canal collapse.

Ascending Technique (Hughson-Westlake)

Threshold search method: down 10 dB after response, up 5 dB after no response until two of three responses at a level.

Sweep-Up Method

Familiarization approach gradually increasing intensity from soft to loud to demonstrate test tone to patient.

Occlusion Effect

Artificial improvement of BC thresholds at low frequencies when the test ear is covered, necessitating uncovered ears in BC testing.

Pure-Tone Average (PTA)

Mean of selected AC thresholds used to predict speech threshold and gauge communication impact.

Three-Frequency PTA

Average of 500, 1000, and 2000 Hz thresholds.

Two-Frequency PTA

Average of the two best thresholds among 500, 1000, 2000 Hz—useful for steeply sloping losses.

Variable PTA

Average of the three poorest thresholds at 500, 1000, 2000, and 4000 Hz to reflect communication difficulty.

Scale of Impairment

Categorization of hearing loss degree: none (−10–15 dB), slight (16–25), mild (26–40), moderate (41–55), moderately severe (56–70), severe (71–90), profound (91+).

Compression Bone Conduction

Skull vibration mode where cochlear shell expansion and contraction stimulate the basilar membrane.

Masking (Audiology)

Introduction of noise to the non-test ear to obtain ear-specific thresholds.

Cross Hearing

When sound presented to one ear is heard by the opposite ear via skull vibration, potentially contaminating results.

Automatic Audiometry

Computer-controlled pure-tone testing that reduces clinician time while allowing oversight for instruction and interpretation.