Rollover measurements with Auditec NU-6 word lists

Area of Science:

• Audiology
• Neuroscience
• Speech-Language Pathology

Background:

• Auditory function assessment relies on understanding how word recognition changes with sound intensity.
• Differentiating cochlear (inner ear) from retrocochlear (auditory nerve/brain) hearing loss is crucial for appropriate treatment.
• Performance-intensity functions for phonetically balanced words (PI-PB) are a key tool in audiological diagnostics.

Purpose of the Study:

• To evaluate the utility of the rollover index derived from PI-PB functions in distinguishing between cochlear and retrocochlear hearing loss.
• To analyze PI-PB functions in individuals with normal hearing, cochlear disorders, and retrocochlear lesions.
• To identify potential factors influencing PI-PB test results and diagnostic accuracy.

Main Methods:

• Utilized Auditec cassette recordings of NU-6 word lists to generate PI-PB functions.
• Tested 25 normal-hearing subjects, 19 with presumed cochlear disorders, and 9 with confirmed retrocochlear lesions.
• Calculated the rollover index for each subject.

Main Results:

• A rollover index exceeding 0.35 effectively differentiated most retrocochlear from cochlear hearing loss.
• Some subjects with confirmed retrocochlear lesions exhibited rollover indices below 0.35.
• Variability in PI-PB functions was observed across diagnostic groups.

Conclusions:

• The rollover index is a valuable, though not infallible, indicator for differentiating cochlear and retrocochlear hearing loss.
• Further research is needed to understand the factors contributing to variability in PI-PB rollover indices.
• Clinical interpretation of PI-PB functions should consider individual patient factors and potential diagnostic ambiguities.