Audio Lecture Notes

School of Engineering

  • TEMASEK POLYTECHNIC

  • EBI3004 Audiometry & Hearing Devices

  • AY10/11

  • Topic 3: Pure Tone Audiometry

Objectives

  • Ability to conduct Pure Tone Audiometric tests for basic hearing assessment.

  • Familiarity with required questions for clinical history.

  • Clear instructions to clients and correct placement of headphones.

  • Proper threshold-seeking techniques for air and bone conduction thresholds.

  • Ability to explain results to clients.

Pure Tone Audiometry (PTA)

  • PTA measures a person's hearing sensitivity across various frequencies using a pure tone audiometer.

  • Results are plotted on a pure tone audiogram.

Audiometer Requirements

  • Properly calibrated audiometer covering frequencies from 250 to 8000 Hz.

  • Equipped with air and bone conduction testing facilities.

  • Calibrated headsets for accuracy.

Audiogram Overview

  • Records the softest sounds a client can hear across frequencies, indicating hearing threshold level.

  • Layout: Low frequencies (pitch) on the left; high frequencies on the right.

  • Audiogram displays potential hearing loss and shape of hearing profile.

Hearing Thresholds

  • 0 dB HL marks the softest sound a normal hearing person can detect.

  • Hearing thresholds plotted on the audiogram: normal hearing (up to 25 dB), mild (26-40 dB), moderate, severe.

Interpreting Audiograms

  • Red circles indicate right ear thresholds, blue crosses indicate left ear thresholds.

  • Hearing loss classification: normal hearing, mild, moderate, severe, profound.

Conducting Tests Without Masking

  • Start PTA testing at 1 kHz and 40 dB for normal hearing, adjust for suspected hearing loss.

  • Determine thresholds using a systematic presentation of tones.

Threshold Seeking Technique

  • Initial descent from starting loudness to find the threshold through UP5-DOWN10 methods.

  • Confirm thresholds with at least a 50% response rate.

Special Conditions for Testing

  • Alternate frequencies may be tested based on threshold differences or noise exposure history.

  • Monitor for collapsing canals or other physical conditions that may affect results.

Bone Conduction Testing

  • Determines the type of hearing loss by bypassing the outer ear.

  • Evaluates inner ear functionality versus conductive loss.

Audiometric Checks

  • Daily listening checks and calibration of audiometers to maintain testing accuracy.

  • Consistency in results verified through technique adherence and detailed record-keeping.

Summary Points

  • Conductive hearing loss originates from issues in outer/middle ear; sensorineural originates from inner ear.

  • Noise exposure regulations protect against occupational noise-induced hearing loss (NID).

  • Importance of proper device care, training, and compliance in hearing test environments.