Puretone Audiometry

Sound Booth

• Specially designed sound-attenuating room.

• Increases sound absorption and reduces sound reflection.

• Patient positioning may vary; avoid inadvertent cues (hand, head, eye movements, facial expressions, visible reflections).

  • For pediatric patients, face them to maintain their attention.

Audiometer

• Electronic or computer-based instrument used for behavioral audiometric evaluations.

Transducers

• Instruments that convert energy from one type to another for presenting sound via air or bone conduction.

• Color-coded for each ear.

1Insert Earphones

• Placement: Outer edge just within the first bend of the ear canal, held in place by a foam cuff (compress prior to insertion).

• Cons: Single use; replace for each patient.

• Pros: Reduces background noise, reduces the need for masking.

Supra-Aural Earphones

• Sit on top of the pinna.

• Placement: Align center of earphones with the opening of the ear canal, held by a headband designed to maintain tension.

• Cleaned between each patient.

• Cons: Can be uncomfortable.

• Pros: Suitable for testing those with atresia or profound hearing loss (with ENT approval for active ear drainage).

Circumaural Earphones (Extended High Frequency (EHF) Earphones)

• Sit around the pinna, covering the entire ear.

• Designed to test frequencies (>8000extHz)

• Pros: EHF testing, ototoxic monitoring, noise-induced hearing loss monitoring.

Soundfield Speakers

• Tests air conduction.

• Used for: Patients who will not tolerate head/earphones (e.g., pediatric patients), patients wearing hearing aids/cochlear implants, aided testing.

• Limitation: Both ears receive the sound; not possible to get ear-specific information.

Bone Conduction Vibrator (Oscillator)

• Tests bone conduction threshold.

• Plastic casing vibrates by puretone, delivering it mechanically to the skull to stimulate the inner ear.

• Placement: On the mastoid bone (behind the ear) or forehead, held in place with a tension headband.

• Should NOT touch the pinna.

• Placed under hair (hair between device and bone can interfere with results).

Air Conduction

• Mode of sound presentation through earphones (supra-aural, inserts, circumaural) or soundfield speakers.

• Stimulates the entire auditory pathway (outer, middle, and inner ear).

• Determines the DEGREE of hearing loss.

Bone Conduction

• Mode of sound presentation through a bone oscillator.

• Stimulates the sensorineural portion only, bypassing the conductive (outer and middle ear) portion.

• Determines the TYPE of hearing loss.

Procedure Steps

1. Introduce yourself and wash/sanitize hands.

2. Perform otoscopy first (look in ears for pre-existing conditions like infection or blockage).

3. Provide clear instructions for PT testing:

   • Instruct the patient to respond to the faintest level of sound.

   • Specify the mode of response (e.g., raise hand, press button, say “yes”). Encourage response even if unsure.

4. Typically, test Air Conduction (AC) before Bone Conduction (BC).

Puretone Presentation

• Present tone by pressing and releasing the presentation button.

• Types: Steady tone, Pulsed tone, Warble tone.

• Presentations should be (1−2)seconds in duration.

• Use variable pauses (1−4) seconds between presentations.

Modified Hughson-Westlake Procedure (”down-10-up-5” bracketing procedure)

• tart at 30

• If no response, increase by 20 until the patient responds (familiarization).

• Once the patient responds, decrease by 10 until there is no response.

• Increase tone by 5extdB5extdB until the patient responds.

• Continue using the “down 10 and up 5” method until the threshold is obtained.

• Threshold: Defined as two responses out of three presentations at a single level.

Interoctave Frequencies

• Tested if there is a (≥20dB0 difference between adjacent frequencies.

Hearing Screen

• Selects a number of frequencies presented at one level.

• Results in a "Pass" (hears it) or "Refer" (does not hear it).

• Used to identify individuals who need follow-up testing; ideal for ruling out concerns in a large population.

• SLPs can conduct hearing screenings; audiologists conduct speech screenings.

Hearing Threshold

• Detects the softest sound that can be heard by an individual (searching for the lowest level of sounds).

• Provides more diagnostic information overall.

Test-Retest Reliability:

• Difference in threshold responses on different occasions.

• (±5dB) is acceptable and expected.

• Thresholds are behavioral, based on responses the patient is able/willing to provide. Document if reliability is questionable.

Variable Responses: False Negative

• Patient does not respond to a signal that was heard.

  • Instruction: “Listen carefully and push the button even for the faintest sound.”

Variable Responses: False Positive

• Patient responds when no signal is presented.

  • Instruction: “Make sure you only push the button when you hear a tone.”

• It is important to vary pauses between presentations.

Variable Responses: “Partial” Responses

• Patient cocks their head, shows a facial expression conveying they heard a tone, or holds up a hand partway/hovers thumb over the button.

  • Instruction: “Go ahead and raise your hand all the way up (or push the button) even if you think you hear the sound.”

  • CAUTION: This may lead to more false positives.

Pediatric and Difficult-to-Test Populations

Alternative Stimuli (instead of puretones)

• Warble tones

• Narrow-band noises

Alternative Audiometry (instead of conventional audiometry)

• Conditioned-Play Audiometry (CPA):

  • Ages (2−4) years.

  • Conditions the child to a response (gamified test).

• Visual Reinforcement Audiometry (VRA):

  • Ages (6months–2years) (requires control of neck muscles).

  • Uses a loud speaker/headphones; observes for a head turn with reinforcement of a cartoon.