Effects of temporal smearing on temporal resolution, frequency selectivity, and speech intelligibility

Area of Science:

• Auditory perception
• Speech processing
• Signal processing

Background:

• Temporal smearing is a technique used to alter the temporal envelope of speech signals.
• Understanding its effect on speech intelligibility is crucial for auditory research and hearing aid development.

Purpose of the Study:

• To investigate the impact of temporal smearing magnitude on speech intelligibility in normal-hearing listeners.
• To analyze how different temporal window durations affect consonant recognition based on articulatory features.

Main Methods:

• Speech signals were processed using temporal smearing across 23 frequency channels.
• Normal-hearing listeners completed speech recognition tasks with smeared speech under low- and high-pass filter conditions.
• Speech intelligibility was measured using overall scores and consonant recognition scores grouped by articulatory features.

Main Results:

• Temporal smearing with a narrow temporal window did not significantly degrade speech intelligibility.
• Increased equivalent rectangular durations (ERDs) of the resultant temporal window (RTW) led to a small but significant reduction in speech intelligibility, especially in the low-pass condition.
• While significant differences were observed for RTWs > 16 ms compared to 7.7 ms in the high-pass condition, the effect was small and consistent across articulatory features.

Conclusions:

• The auditory system exhibits robust temporal resolution, tolerating moderate levels of temporal smearing without substantial loss of speech intelligibility.
• Speech intelligibility is sensitive to temporal smearing, particularly under low-pass filtering, with larger temporal smearing causing a slight decline.
• Articulatory features of consonants are largely preserved in intelligibility despite temporal smearing, indicating resilience in phonetic perception.