Amplitude variation in calibrated audiometer systems in clinical simulations

Area of Science:

• Audiology
• Occupational Health
• Acoustics

Background:

• Manual pure tone audiometry is the established standard for hearing threshold assessment.
• Increased legislative demands for hearing loss monitoring and screening heighten reliance on audiometry.
• Concerns exist regarding the accuracy of pure tone audiometry in field conditions compared to laboratory settings.

Purpose of the Study:

• To analyze the sound pressure level output accuracy of commercial audiometers under simulated clinical conditions.
• To quantify test-retest variability in pure tone audiometry screening.
• To identify factors contributing to potential errors in hearing screening.

Main Methods:

• Four commercial audiometers with TDH39 headphones were tested using a Head and Torso simulator.
• A trained audiometrist simulated clinical conditions, replacing headphones for each test.
• Measurements were taken at multiple presentation levels and frequencies (250 Hz to 6 kHz).

Main Results:

• High test-retest variability was observed across different audiometers and within the same device.
• Maximum sound pressure level variation reached 21 decibels, with notable inconsistency at 6 kHz.
• Audiometers with attenuating cups showed significantly higher variation than those with supra-aural headphones.

Conclusions:

• Screening pure tone audiometry may have higher potential error rates than commonly assumed.
• Results, particularly at the 6 kHz frequency, require careful interpretation alongside other methods like speech audiometry.
• The study highlights the need for improved accuracy and validation of audiometric screening tools in occupational settings.