Speech Audiometry

Introduction

• Speech Audiometry: Evaluates the patient's ability to hear and understand speech.
• Purpose: Primarily used for fitting hearing aids.
• Relevance: Important for ENT surgeons and audiologists; significant for NEET PG exams.

Key Concepts and Tests

1. Speech Reception Threshold (SRT)

   • Definition: Intensity at which the patient can hear and repeat back 50% of spoken words.
   • Procedure: Use of spondee words, increasing intensity by 5 dB until 50% of words are correctly repeated.
   • Use: Should be within 10 dB of Pure Tone Audiometry (PTA) average; deviations may indicate malingering.

2. Speech Discrimination Score (SDS)

   • Definition: Percentage of single-syllable words correctly repeated by the patient at a suprathreshold level.
   • Procedure: Phonetically balanced words given at 30 dB above SRT; calculates percentage of correct repetition.
   • Understanding: Normal/conductive hearing loss typically allows 90-100% repetition; lower scores indicate processing issues.

3. PB Max (Phonetically Balanced Max)

   • Definition: Maximum speech discrimination score across various intensities.
   • Procedure: Testing across decibels (0-100 dB) to find intensity with maximum correct word repetition.
   • Use: Differentiating cochlear from retrocochlear hearing loss.

Practical Applications

• Hearing Aid Fitting: Determines optimal intensity for hearing aid settings based on PB Max.
• Patient Understanding: Evaluates capability to comprehend speech in varying conditions, e.g., whispers with background noise.

Interpretation of Results

1. Normal and Conductive Hearing Loss

   • PB Max at lower intensities (e.g., 15 dB); follows S-shaped curve.
   • Conductive loss may reach 100% at higher intensities (e.g., 70 dB).

2. Cochlear Sensorineural Hearing Loss

   • PB Max reached at higher intensities (e.g., 70 dB) without reaching 100%.
   • Results in a plateau, indicating processing limitations.

3. Retrocochlear Hearing Loss

   • PB Max at even higher intensities (e.g., 80 dB); does not reach 100%.
   • Exhibits rollover phenomenon where PB score decreases with increasing intensity.

Conclusion

• Speech Audiometry: Critical for assessing hearing loss and fitting hearing aids appropriately.
• Uses: Differentiation between various types of hearing losses, detection of malingering, and optimal hearing aid settings.

Thank you for listening.