Development and evaluation of the listening in spatialized noise test

Area of Science:

• Audiology
• Psychoacoustics
• Speech Perception

Background:

• Assessing speech understanding in noise is crucial for audiological evaluations.
• Existing tests often struggle with listener variability (e.g., attention, language skills).
• Ecologically valid tests simulating real-world listening conditions are needed.

Purpose of the Study:

• To design and validate the Listening in Spatialized Noise Test (LISN) for measuring speech understanding in background noise.
• To minimize listener-specific variations in performance.
• To assess LISN's ability to simulate free-field conditions and examine learning effects.

Main Methods:

• A three-alternative forced choice adaptive procedure was used with 20 normal-hearing adults.
• Target speech was presented at 0 degrees azimuth with distracter sentences at 0 degrees or +/-90 degrees azimuth.
• Distracter speaker conditions included same female, different female, and male voices.

Main Results:

• Listeners demonstrated significantly better speech understanding with spatially separated distracters (+/-90 degrees) compared to co-located distracters (0 degrees).
• The spatial separation advantage (SSA) decreased as vocal differences between target and distracter speakers increased.
• SSA in varied voice conditions approximated free-field measurements; test-retest scores showed stability.

Conclusions:

• Binaural cues (e.g., interaural time differences) facilitate speech comprehension when distracters are spatially separated.
• Reduced reliance on spatial cues occurs when vocal characteristics clearly distinguish target from masker.
• LISN offers a stable, ecologically valid tool for assessing auditory processing, minimizing listener variability.