Is speech intelligibility what speech intelligibility tests test?

Area of Science:

• Audiology
• Linguistics
• Speech-Language Pathology

Background:

• Natural speech conveys both symbolic (lexical, syntactic) and iconic information crucial for full comprehension.
• Traditional speech intelligibility tests, derived from written language, primarily assess symbolic information.
• These tests often neglect vital information from talkers, such as communicative intentions and cognitive states.

Purpose of the Study:

• To compare information sources in standard speech intelligibility tests versus spontaneous conversational speech.
• To highlight differences in signals and listener tasks between test conditions and natural communication.
• To examine the implications for interpreting and generalizing speech intelligibility test findings.

Main Methods:

• Descriptive comparison of information content in three common speech intelligibility tests.
• Analysis of spontaneous conversational speech elicited via a referential communication task.
• Evaluation of information sources available to listeners in each condition.

Main Results:

• Speech intelligibility tests provide a limited view, excluding most iconic information and talker-specific cues.
• Conversational speech offers a richer set of symbolic and iconic information sources.
• Listener tasks differ significantly between standardized tests and natural speech perception.

Conclusions:

• Current speech intelligibility tests measure only a fraction of the speech perception process.
• Findings from standard tests may not accurately reflect real-world speech understanding.
• Revising test methodologies is necessary to capture the full scope of speech perception and improve diagnostic accuracy.