Stimulus and transducer effects on threshold.

Area of Science:

• Audiology
• Hearing Science
• Biomedical Engineering

Background:

• Traditional audiometric testing often relies on supra-aural earphones like the Telephonics TDH-39P.
• Advancements in headphone technology, such as circumaural designs like the Sennheiser HDA200, warrant investigation for their impact on audiological assessments.
• Understanding the reliability of different stimuli (pure tone, noise bands) with new equipment is crucial for accurate hearing evaluations.

Purpose of the Study:

• To compare the reliability of hearing thresholds obtained with Sennheiser HDA200 circumaural earphones against Telephonics TDH-39P supra-aural earphones.
• To evaluate the performance of pure tone, equivalent rectangular noise bands (ERBs), and 1/3 octave noise bands with the HDA200 earphones.
• To assess the impact of stimulus bandwidth on the reliability and frequency-specificity of audiometric measurements.

Main Methods:

• Audiometric thresholds were measured six times within 10 days for 49 adults with varying threshold reliability.
• Testing involved Sennheiser HDA200 and Telephonics TDH-39P earphones using pure tones and different noise band stimuli.
• Data were analyzed to compare the reliability and consistency of thresholds across different earphone types and stimulus conditions.

Main Results:

• Sennheiser HDA200 earphones demonstrated equal or superior reliability for pure-tone thresholds compared to TDH-39P earphones.
• Noise band thresholds showed improved reliability with broader bandwidths, outperforming pure-tone thresholds in some cases.
• Frequency-specificity decreased with stimulus bandwidths exceeding one ERB, potentially hindering the detection of narrow-frequency hearing changes.

Conclusions:

• Circumaural earphones, specifically the HDA200, offer enhanced reliability for audiometric testing over TDH-39P earphones.
• Noise bands, particularly ERB noises, are recommended as effective stimuli for reliable audiometric monitoring.
• Careful consideration of stimulus bandwidth is necessary to balance reliability and frequency specificity in hearing assessments.