Immittance audiometry. Normative data at 220 and 660 Hz

Area of Science:

• Audiology
• Otology
• Medical Physics

Background:

• Accurate immittance audiometry relies on normative data for normal ears.
• Understanding tympanometric shapes, like W-shaped tympanograms, is crucial for interpreting middle ear function.

Purpose of the Study:

• To establish normative immittance data for normal ears at 220 and 660 Hz probe tone frequencies.
• To investigate the occurrence and characteristics of W-shaped tympanograms in healthy individuals.

Main Methods:

• Collected normative immittance data (susceptance, conductance) from normal ears at 220 and 660 Hz.
• Utilized an experimental setup for converting data to resistance, reactance, admittance, and phase angle tympanograms.
• Implemented precise subtraction of ear canal admittance and controlled pump speed.

Main Results:

• W-shaped tympanograms were observed in 43.2% of healthy ears at 660 Hz probe tone.
• The occurrence of W-shaped tympanograms was not influenced by age, sex, or pump direction.
• Normative data for the central extremum were reported only for immittance components without W-notching due to wide population variance.

Conclusions:

• W-shaped tympanograms are a common finding in healthy ears at 660 Hz.
• Population-wide normative subcategories are not feasible due to measurement variance.
• Intra-individual variation is minimal; using the contralateral healthy ear as a reference is recommended for immittance audiometry.