Hearing Measurement Lect.02Pure-Tone Audiometry

Hearing Measurement Lecture Notes

• The lecture covered pure-tone audiometry, focusing on why measuring thresholds is important.
• Measuring thresholds helps determine the extent of hearing loss.
• The strange nature of speech perception was discussed, noting that speech has a complex spectrum.
• Detailed and coarse speech spectra were presented, illuminating the frequency components of speech.
• The role of detail in speech perception was highlighted.
• The presentation questioned if measuring thresholds was too focused or too soft. 
• An image of a cochlea, with different parts labeled, supplemented the discussion.
• A graph related loudness, sones, phons, and loudness level.

Frequency-Specificity and Place-Specificity

• Place specificity is achievable only with frequency-specific tones at low sound levels.

Importance of Audiometry

• Audiometry is crucial for a variety of reasons, including assessing hearing function.
• Various methods and tools for performing audiometry, images of the equipment (headphones, audiogram, etc.) were shown.
• Types of audiometric data recorded were discussed, like air conduction, bone conduction, etc.

What Affects Performance in Real Life?

• Various factors in real-life, including social situations and distractions, may affect hearing.
• The importance of using appropriate and controlled test conditions.

The Audiogram

• This graph shows hearing thresholds on the vertical axis and frequency on the horizontal axis.
• Shows how audiometric data could appear on a visual graph.

Audiogram of Familiar Sounds

• This graph visualises the sound pressure levels of different everyday sounds at specific frequencies.

Role of Outer and Middle Ear in Hearing

• The outer and middle ear play essential roles in amplifying sound and channeling sound to the inner ear.

Human Hearing

• A graph showing the relationship between sound pressure level and loudness.
• Includes the normal binaural minimum audible field (MAF) and other important auditory thresholds.
• The graphic highlights the approximate pain threshold and loudness discomfort levels, alongside the conversational speech levels.

dB SPL to dB HL Transform

• This illustrates the transformation of sound pressure level (SPL) to hearing level (HL)
• A reference level for hearing is demonstrated.

What is a Threshold?

• Threshold is a hearing level at which a person can perceive a tone 50% of the time.
• Measurements should include hit and miss rates.

The Role of the Criterion

• The likelihood of a response is linked to the sensory input level.
• The criterion plays a role in the test results.

The Audiogram (Audiogram examples)

• Demonstrates an audiogram showing the hearing thresholds for both ears across different frequencies.

The Audiometer (Description)

• The different sections/components of a standard or advanced clinical audiometer system.
• Examples of specific audiometer models (e.g Madsen Astera, GSI AudioStar).
• Practical details on using the audiometer were not shown, the models displayed were not explained in the specifics.

GSI Audiostar

• A specific example of an audiometer, featuring a screen display.

Automated Testing

• Automated testing for hearing, an example shown.

The Screening Audiometer (Description)

• An example of a screening audiometer, highlighting its features.

First Things First: Control

• Importance of control conditions (sound booth) for accurate hearing tests.
• Examples of equipment used for controlling and monitoring audio conditions.

Ambient Noise

• This discusses the sound levels that are permitted for audiological testing.
• Tables show the maximum permissible ambient noise levels for both supra-aural and insert earphones, at different frequencies.

Air Conduction Audiometry (Description)

• Discussion on air conduction audiometry and the types of equipment used.

Transducer Choice: Pros and Cons

• Audiometry equipment options (types of headphones/inserts) were displayed and discussed.

Reference Equivalent Threshold Sound Pressure Levels

• Table showing the reference equivalent threshold sound pressure levels for a variety of audiometric situations.

dB SPL to dB HL Transform

• The notes include a diagram showing the conversion from one to the other.

Describing Hearing Loss: Percentages (AMA)

• Shows a graph demonstrating different categories of hearing loss at different percentages.

Describing Loss: The Pure Tone Average

• The average of the hearing levels of 500, 1000, and 2000 hertz is useful in evaluating overall hearing ability.
• The Fletcher average is a concept used for calculating hearing loss.

Degree of Hearing Loss

• The data shows a visual representation of the different severity degrees of hearing loss from mild to profound hearing loss.

Configurations of Hearing Loss (Rules of 20)

• Various configurations of hearing loss based on an audiogram of a test. Many examples of different forms were shown/discussed, the diagrams used to explain.

Audiometric Procedures

• Steps/principles associated with audiometric testing procedures

Audiogram Symbols

• Explains how audiograms are read and interpreted: the different symbols, their meanings in the context of the audiogram, including types of testing.

Drawing an Audiogram

• Example of how an audiogram is drawn to visualize hearing loss patterns. Specific symbols used to describe different aspects of the hearing assessment were also covered.

Arrangement: Screening and Diagnostic

• Diagrams illustrate different arrangements for conducting hearing tests in screening and diagnostic settings. 

Transducer Placement

• Highlights important considerations for who conducts the tests, and what instruments should be used in the different situations, e.g. Bone oscillator, inserts. 

The 'Button'

• Identifies a critical component of an audiometer.

Obtaining AC Audiogram ANSI S3.21 (1978)

• Procedures for obtaining air conduction (AC) audiograms. This section outlined the protocols to follow for a comprehensive assessment.

False Responses and Patient Responses

• Discussion of common errors, such as false responses.
• How these may occur and what to do to minimize issues or prevent inaccuracies in interpreting results, and how to correct for errors.

Examples of Audiograms

• Examples of audiograms, illustrating various degrees and types of hearing loss, and how to interpret them. 

Sensorineural Hearing Loss, Conductive Hearing Loss, Mixed Hearing Loss

• Visual representations of audiogram profiles for these categories.

Appendix (Notes)

• Supplementing notes or additional details on the topics covered in the main body of the lecture.

Onset

• Different type (e.g. congenital, acquired, adventitious).

Time Course

• Overviewing the various time-based classifications of loss (e.g. chronic, acute, gradual).

Tuning Fork Tests: Weber, Rinne, Bing

• Description, and procedures of the Tuning Fork tests.