Audiogram Interpretation

Audiogram

Graph used to plot audiometric

thresholds

• X-axis: frequency (Hz)

• Top or bottom

• Y-axis: intensity levels (dB HL)

• Puretone (PT): simple sound waves that have only one frequency of

vibration (an assessment of some sort, if they can hear a puretone)

Audiometry: assessment of a person’s responses to sounds

• Pure-tones, warble tones, speech, etc.

• Audiometric: pertaining to measures made with audiometry

Threshold (Θ): lowest level of a puretone that a person reliably

responds to at least 50% of the time (searchng fr threshhold make sure get true response (need to respond 2 times at same level) not an accident

Minimum number of responses needed to determine the threshold of hearing is

two responses out of three presentations at a single level (American National

Standards Institute, 2004a)

Conductive: outer ear + middle ear

Sensorineural portion: inner ear, 8th nerve, central system

Air conduction:

Mode of sound presentation

through earphones

  • stimulates entire auditory pathway

  • determines DEGREE of hearing loss (tell how severe)

  • talking normally

Bone conduction:

Mode of sound presentation through

bone oscillator

  • stimulates sensorineural portion

  • determines TYPE of hearing loss

  • Loud concert hear vibrations

Soundfield:

Centered on vertical lines of

appropriate frequency / intensity

• Used for pediatric / aided testing

• Cannot obtain ear specific

information

Puretone Audiogram

Three types of information conveyed:

1. Degree (amount) of hearing loss

2. Type of hearing loss

3. Shape (configuration) of hearing loss

Degree of hearing loss

  • adults -10-25 dB,

  • kids -10-15 dB (more spcific to make sure kids are not missing speech sounds so more strict threshold)

Type of Hearing Loss Considerations

Type of hearing loss should be

considered at each frequency

• Different type of loss in different

frequency areas

• Example: unilateral low frequency CHL

Shape of Hearing Loss: what shape (slopinh, flat, rising)

  • Describing the shape / configuration of a hearing

    loss provides a mental picture of how thresholds

    look / change across frequencies

    • “a bilateral sensorineural hearing loss, sloping from

    mild in the low frequencies”

  • HIGH FREQ SLOPING hearing loss most common (high frequencies go first)

The Speech Banana

vowels = power

  • high freq. hearing loss can still understnad speech with sloping hearing loss

consonants = clarity

  • (go across the board)

  • miss voiceless fricatives first, help with clarity of speech)

Cochlear implants make speech sounds sound different, need to reconfigure sounds in brain

Important for pre-lingual clients, helps to develop these sounds, not as useful for aduts that already know the sound

Audiogram Situations to Consider

Tactile Responses

  • Result in a patient feeling the sound rather than hearing (sound levels so loud you can feel it)

    • Occur mostly by BC for low frequencies

    • 25 – 40dB at 250Hz

    • 55 – 70dB at 500Hz

    • Falsely implies a significant ABG / conductive component to hearing

    loss

    • How to tell?

    • Ask the patient whether they are feeling the signal


No Response at Output Limits

  • Upper limits of audiometer reached, and patient does not respond

    • Appropriate AC / BC symbols plotted at max level with arrows

    attached

    • Output limits may vary depending on audiometer

    • AC: ~120dB HL

    • BC: ~80dB HL

Collapsed Canals

May occur in individuals with reduced elasticity in cartilaginous

portion of ear canal with the use of supra-aural headphones (hept in place with tention (stay in place so they don’t shuffle)

• Reduces intensity of AC signals (not BC)

• Result in ABG

• Effects usually seen in mid to high frequencies

• What to do if collapsed canal is suspected?

• Change transducer to insert earphones (ears don’t get bigger ear canal gets weaker can close ear canal on test from. pressure headphones)

Audiogram Basics

An audiogram is a graph used to plot audiometric thresholds.

  • X-axis: Frequency in Hertz (HzHz). This can be displayed at the top or bottom of the graph.

  • Y-axis: Intensity levels in decibels Hearing Level (dBHLdBHL). The higher the number, the louder the sound.

Key Terms and Definitions

  • Puretone (PT): Simple sound waves with only one frequency of vibration. These are used in assessments to determine if a person can hear specific frequencies.

  • Audiometry: The assessment of a person’s responses to various sounds, including pure-tones, warble tones, and speech.

  • Audiometric: Pertaining to measures made with audiometry.

  • Threshold (ΘΘ): The lowest level of a puretone at which a person reliably responds at least 50% of the time. To ensure a true response and not an accident, the minimum number of responses needed to determine a hearing threshold is typically two responses out of three presentations at a single level (American National Standards Institute, 2004a).

  • Conductive Portion: Refers to the outer and middle ear.

  • Sensorineural Portion: Refers to the inner ear, the 8th cranial nerve, and the central auditory system.

Modes of Sound Presentation

  • Air Conduction (AC):

    • Sound is presented through earphones.

    • Stimulates the entire auditory pathway.

    • Determines the degree (severity) of hearing loss.

  • Bone Conduction (BC):

    • Sound is presented through a bone oscillator, placed on the mastoid or forehead.

    • Stimulates only the sensorineural portion of the auditory pathway.

    • Determines the type of hearing loss.

  • Soundfield:

    • Sound is presented through loudspeakers, often centered on vertical lines of appropriate frequency/intensity.

    • Used primarily for pediatric or aided testing (e.g., with hearing aids).

    • Cannot obtain ear-specific information as both ears receive the sound simultaneously.

Information Conveyed by a Puretone Audiogram

A puretone audiogram conveys three types of information:

  1. Degree (amount) of hearing loss: How severe the hearing loss is.

    • Adults: Normal hearing is typically considered between −10−10 to 25dBHL25dBHL.

    • Kids: Normal hearing thresholds are set more strictly, between −10−10 to 15dBHL15dBHL, to ensure they are not missing crucial speech sounds for development.

  2. Type of hearing loss: Whether it is conductive, sensorineural, or mixed.

    • The type of hearing loss should be considered at each frequency, as a person can have different types of loss in different frequency areas (e.g., unilateral low-frequency conductive hearing loss).

  3. Shape (configuration) of hearing loss: Describes how thresholds look or change across frequencies, providing a mental picture of the hearing loss.

    • Common shapes include sloping, flat, or rising.

    • A common configuration is a high-frequency sloping hearing loss, where high frequencies are affected first.

    • Example description: “a bilateral sensorineural hearing loss, sloping from mild in the low frequencies.”

The Speech Banana

The speech banana is an area on the audiogram that contains the frequencies and intensities of typical human speech sounds.

  • Vowels: Carry more power in speech. Individuals with high-frequency sloping hearing loss may still understand speech because the low-frequency vowel sounds are often better perceived.

  • Consonants: Carry more clarity in speech. Voiceless fricatives are often missed first in hearing loss, impacting speech clarity.

Cochlear Implants

Cochlear implants process speech sounds differently, requiring the brain to reconfigure how it interprets these sounds. They are particularly important for pre-lingual clients (those who haven't developed speech yet) to help develop sound perception, but they are generally less useful for adults who already possess developed sound recognition.

Audiogram Situations to Consider
Tactile Responses

  • Occur when a patient feels the sound rather than hearing it, especially at very loud sound levels.

  • Most common with bone conduction for low frequencies:

    • 25−40dBHL25−40dBHL at 250Hz250Hz

    • 55−70dBHL55−70dBHL at 500Hz500Hz

  • Can falsely imply a significant air-bone gap (ABG) or a conductive component to hearing loss.

  • How to tell: Ask the patient whether they are feeling the signal rather than hearing it.

No Response at Output Limits

  • This occurs when the upper intensity limits of the audiometer are reached, and the patient still does not respond.

  • Appropriate AC/BC symbols are plotted at the maximum level, with an arrow attached, indicating no response at maximum output.

  • Output limits can vary by audiometer, but typically:

    • Air Conduction (AC): ~$120 dB HL

    • Bone Conduction (BC): ~$80 dB HL

Collapsed Canals

  • May occur in individuals with reduced elasticity in the cartilaginous portion of the ear canal when using supra-aural headphones (headphones that rest on the outer ear).

  • The pressure from the headphones can cause the ear canal to collapse, reducing the intensity of air conduction signals (but not bone conduction).

  • Results in an air-bone gap (ABG) where none might exist.

  • Effects are usually seen in mid to high frequencies.

  • What to do if collapsed canals are suspected: Change the transducer to insert earphones, which do not apply pressure to the cartilaginous part of the ear canal and help keep it open. Ear canals do not get bigger, but their elasticity can weaken over time.