Preparation for Pure-Tone Testing

Preparation for Pure-Tone Testing

Settings for Audiologists

  • Audiologists may establish practices in a variety of settings including:

    • Private practice

    • University clinics

    • Medical schools

    • Hospitals

    • Medical offices

    • School district diagnostic centers

  • All of these settings facilitate pure-tone testing, which serves as a fundamental aspect of comprehensive audiologic evaluation.

  • Services offered may depend on the type of clinic and the audiologist's area of expertise.

Considerations for Clinical Space Development

  • Factors to consider in developing a hearing clinic include:

    • Acquisition of state-of-the-art equipment

    • Establishment of offered services

    • Determination of accepted third-party payments

    • Assurance of patient accessibility and comfort

    • Maximization of referral sources

    • Marketing of services.

Equipment for Pure-Tone Testing

Sound-Treated Booths

  • Pure-tone tests are conducted in sound-treated booths or suites to minimize environmental noise.

  • Booths:

    • Come in various sizes; larger booths may be necessary for pediatric testing or hearing aid evaluations.

    • Must adhere to ANSI (2004) specifications regarding ambient noise levels measured in one-third octave frequency bands.

  • Audiologists often work in a quiet area to minimize electrical and acoustic interference.

  • The setup generally includes:

    • Direct sightlines between the patient inside the booth and the audiologist outside.

    • Some clinics may use side-by-side booths for simultaneous testing sessions.

Types of Audiometers

  • Five main audiometer types are specified by ANSI (2004) ranging from Type 1 (most sophisticated) to Type 5 (basic).

  • Most clinics utilize Type 1 diagnostic audiometers.

  • Audiometer capabilities:

    • Pure-tone testing

    • Speech audiometry

    • Narrow band and speech noise emission for clinical masking.

  • Portable audiometers are useful in non-traditional settings such as schools, senior centers, or bedside evaluations.

  • Various specialized audiometers are available for different audiometric applications, such as automatic audiometry and ultrahigh-frequency testing.

Audiometer Controls

  • Major controls of audiometers include:

    • Frequency Dial:

      • Emits signals from at least 125 Hz through 8 kHz, with ultrahigh-frequency units going up to 20 kHz.

      • Includes major discrete audiometric and mid-octave frequencies.

      • May have a speech setting for live voice stimuli presentations.

      • Important for determining discrepancies in speech and pure-tone test results that could indicate central auditory processing issues.

    • Intensity (Attenuator) Dial:

      • Capable of generating intensities ranging from -10 dB HL to 110 dB HL (extended range up to 125 dB HL).

      • Marks in 5 dB increments, with some audiometers allowing for 1 dB steps.

      • Audiologist determines signal delivery to the right ear, left ear, or both.

      • Signals are delivered through various transducers including earphones, bone conduction oscillators, and loudspeakers.

      • Interruptor Switch used to control the tone's presentation duration.

Transducers

  • Transducers convert energy forms necessary for stimulus delivery during testing.

  • Types of transducers include:

    • Earphones

      • Marked red for right ear, blue for left ear.

      • Requires calibration for specific audiometers.

    • Supra-aural Earphones: Common types include Telephonics Dynamic Headphones (TDH).

    • Circumaural Earphones: Used in noisy environments or for higher frequencies.

    • Insert Earphones: Popular for minimizing collapsing ear canal artifacts; should be properly sized and inserted. Common examples include the ER-3A.

    • Loudspeakers: Used for sound field testing, typically with pediatric testing.

Bone Conduction Testing

  • Delivered through a bone conduction vibrator, stimulating the cochlea directly by bypassing outer and often middle ear structures.

  • Placement requires careful attention to avoid interference and ensure accurate stimulus delivery.

  • BC testing limitations include restricted frequency range and periodic adjustments needed for positional effects.

Calibration and ANSI Standards

Importance of Calibration

  • Calibration ensures accurate audiometric equipment performance, necessary for consistent patient testing across time and settings.

  • Scheduling regular calibration checks is crucial for maintaining audiometer readiness.

  • Calibration must include:

    • Regular checks of both intensity outputs and frequencies using appropriate calibration tools like sound pressure level meters and specific couplers.

    • Utilizing ANSI specifications ensures that results are reliable and inter-comparable across different clinics.

Daily Listening Check

  • Audiologists must conduct daily checks to verify functionality before patient testing.

  • Essential checklist items include:

    • Proper equipment connection

    • Transducer functionality

    • Response verification to various frequencies.

Patient Preparation for Testing

Case History Development

  • Establishing rapport and thorough case history is essential for effective patient assessment.

  • Key areas to explore include:

    • Patient medical history

    • Previous audiologic evaluations

    • Any relevant surgeries or treatments.

Otoscopic Examination

  • Critical for identifying any potential occlusions or abnormalities in the ear canal or tympanic membrane.

  • Identifies presence of cerumen or any abnormalities that need to be addressed prior to testing.

Procedures Preceding Testing

  • Clear instructions should be provided regarding testing procedures.

  • Items such as jewelry, hats, other obstructive materials should be removed prior to placement of transducers.

  • Establish quiet and controlled environment to minimize noise during testing.

Infection Control in Audiology

  • Implementing strict infection control protocols is pivotal for patient safety and to prevent cross-contamination in clinical settings.

  • Hand hygiene, disinfection of equipment, and limiting physical touch with potentially infectious items are necessary practices.

Threshold Methods of Ascertaining and Recording

Definition of Threshold

  • Defined as the softest level of a specified signal that is audible to the listener.

  • Related to the non-linear sensitivity across frequencies in hearing physiology.

Psychophysical Methods for Threshold Determination

  • Method of Adjustment: Patients adjust the stimulus intensity to a point of perceptible sound.

    • Method of Constant Stimuli: Various stimulus presentations allow patients to respond to each signal to determine hearing levels.

    • Method of Limits: Controlled by clinicians, changing stimuli based on patient responses.

    • Modified Hughson-Westlake Procedure: Combines ascending and descending techniques to arrive at threshold levels efficiently.

Audiogram Interpretation

Critical Parameters

Magnitude

  • Classifies hearing loss severity through recorded thresholds, measured across the frequency range.

  • Severity categories assist with clinical referrals and recommendations for further evaluations or interventions.

Type

  • Conductive: Disorders in the outer/middle ear, affecting conductive hearing.

  • Sensorineural: Disorders in the inner ear or central auditory pathways affecting perception of sound.

  • Mixed: Simultaneous conductive issues with underlying sensorineural components.

Symmetry

  • Symmetry compares right and left ear thresholds, informing treatment options and indicating potential central pathology.

Configuration

  • Describes the shape of hearing loss across frequency ranges, affecting diagnosis and rehabilitation recommendations.

Masking

Concept of Masking

  • Masking is interference with the perception of a signal due to the presence of another sound.

  • Different types of noise, such as white noise, speech noise, and narrow-band noise can be utilized in clinical settings to achieve accurate testing conditions.

    • A comprehensive understanding of each outlined topic is vital for effective audiology practice, from preparation for pure-tone testing to interpretation of results and patient counseling. These notes serve as an in-depth resource to support learning and comprehension of complex audiological processes.