Effects of intelligibility on working memory demand for speech perception.

Area of Science:

• Cognitive Psychology
• Speech Perception
• Auditory Neuroscience

Background:

• Perceiving low-intelligibility speech is cognitively demanding.
• Working memory (WM) capacity is crucial for processing challenging auditory information.
• Synthetic speech offers a controlled method to study speech perception and its cognitive load.

Purpose of the Study:

• To investigate how speech intelligibility affects working memory demands during synthetic speech perception.
• To examine the interplay between perceptual learning, speech quality, and working memory capacity.
• To determine if improved intelligibility leads to more efficient use of working memory resources.

Main Methods:

• Three experiments were conducted using a speeded word recognition task paired with a secondary working memory load task.
• Speech intelligibility was manipulated through listener training (Experiment 1) and by altering acoustic cue informativeness (Experiments 2 & 3).
• Working memory availability was varied to assess its impact on speech perception under different intelligibility conditions.

Main Results:

• Listener training significantly enhanced speech intelligibility and recognition speed, but these benefits were only apparent under low working memory load.
• Improvements in speech quality (higher intelligibility) without training increased recognition accuracy but did not enhance the efficiency of working memory use.
• Increased working memory load consistently impaired speech recognition, regardless of intelligibility improvements achieved through enhanced speech quality.

Conclusions:

• Perceptual learning, through training, can modify how cognitive resources are utilized for speech processing, potentially by prioritizing more informative acoustic features.
• While enhanced speech quality improves accuracy, it does not inherently lead to more efficient working memory utilization during perception.
• The findings suggest a complex interaction between learning, speech characteristics, and cognitive capacity in determining the effort required for understanding speech.