Intelligibility of dysphonic speech in auralized classrooms.

Area of Science:

• Speech and Hearing Sciences
• Acoustic Phonetics
• Auditory Perception

Background:

• Voice disorders, such as dysphonia, can significantly impair speech intelligibility.
• Environmental factors like background noise and room acoustics (reverberation) are known to affect speech perception.

Purpose of the Study:

• To investigate the combined effects of voice quality (normal vs. dysphonia), background noise, and room reverberation on vowel intelligibility.
• To assess the impact of these factors on listening easiness and listener reaction time.

Main Methods:

• Nine American English vowels in /h/-V-/d/ format were recorded by speakers with normal voices and speakers with dysphonia.
• Recordings were processed with impulse responses from two classrooms differing in reverberation time (0.4s and 3.1s).
• Processed speech stimuli were presented to 29 college students in a forced-choice listening task.

Main Results:

• Vowel intelligibility and listening easiness were significantly better in quiet conditions compared to noisy conditions.
• Speech from speakers with normal voice quality was more intelligible and easier to understand than from speakers with dysphonia.
• Lower reverberation times (0.4s) resulted in higher intelligibility and listening easiness compared to higher reverberation times (3.1s).
• Listener reaction time increased in noisy conditions and with dysphonic voices.

Conclusions:

• Background noise, dysphonia, and high reverberation negatively impact speech intelligibility and listening ease.
• These factors also increase listener cognitive load, as indicated by longer reaction times.
• Optimizing acoustic environments and addressing voice disorders are crucial for improving speech communication.