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Basic acoustic considerations of ear canal probe measurements
1UCLA School of Medicine, Division of Head and Neck Surgery, (Audiology).
Ear and Hearing
|October 1, 1987
Summary
Probe microphone measurements are significantly affected by probe location within the ear canal. Understanding acoustic properties like standing waves and eardrum impedance is crucial for accurate real-ear gain assessments.
Area of Science:
- Acoustics
- Audiology
- Bioacoustics
Background:
- Real-ear gain measurements are essential for hearing aid fitting.
- Probe microphone placement can influence measurement accuracy.
- Acoustic properties of the ear canal affect sound pressure levels.
Purpose of the Study:
- To review acoustic investigations on probe location effects in real-ear gain measurements.
- To demonstrate the impact of standing waves and eardrum impedance on probe measurements.
- To highlight the importance of standardized probe measurement procedures.
Main Methods:
- Review of theoretical models of human ear acoustics.
- Analysis of ear simulator studies.
- Sound field investigations using a KEMAR manikin and a commercial probe microphone system.
Main Results:
- Probe location critically affects absolute and relative ear canal measurements.
- Standing waves and eardrum impedance significantly influence probe measurements.
- Measurements in the KEMAR manikin confirmed location-dependent SPL and real-ear gain.
Conclusions:
- Probe location is a critical factor in ear canal acoustic measurements.
- Clinical procedures for probe measurements must be based on acoustic principles.
- Standardization is needed for reliable real-ear gain assessments.