28- Speech Production & Perception - Part II (10.31.25)

Speech production & perception

10.31.25

Ch. 12 - Speech & Music

Announcements

• Exam 2
• Wed 11/5
• covers Ch. 9-12
• Attention + everything auditory
• To review

• Emma's recordings & slides
• Vignettes from each chapter

Challenges to Interpreting Speech

• Not a simple one-to-one mapping between specific sounds and phonemes:
• Individual differences across people
• Different dialects (Boston, New York, Louisiana)
• Changes in manner of speech (whispering, shouting, has a cold)
• How phonemes are modulated by the demands of producing neighboring phonemes
• Parsing phonemes into units of meaning

Coarticulation and Perceptual Constancy

The frequencies with which a phoneme is uttered will vary with the demands of producing the preceding and upcoming phoneme We tend to perceive the phoneme the same way in spite of this variation (perceptual constancy, much like color constancy)

Categorical Perception in Speech Processing

We tend to parse speech into distinct phonemic units, with abrupt transitions These boundaries are much sharper than they are in reality, potentially reflecting detectors tuned to a particular range

Integrating Vision and Audition in Speech

Visual information informs speech perception, even in people who are not trained lip readers McGurk effect: when visual and auditory components of speech conflict, the perception tends to be some compromise of the two

The Role of Knowledge in Speech Perception

Our perception of speech is informed by expectations that we generate online given what we have experienced in the past (knowledge) grammatical rules

The Role of Knowledge in Speech Perception

Our perception of speech is informed by expectations that we generate online given what we have experienced in the past (knowledge) probability of specific sequences of phonemes (phoneme transition probabilities)

The Role of Knowledge in Speech Perception

Our perception of speech is informed by expectations that we generate online given what we have experienced in the past (knowledge) probability of specific sequences of phonemes (phoneme transition probabilities)

• Part (a): Eight-month-old infants first listened to 2 minutes of a familiarization stimulus that consisted of four three-syllable “words” presented in random order, with no pauses between the words. The words were constructed so that the transition probabilities between syllables were the only cues to word segmentation.
• (b) In the test phase, the infants listened to two words from the familiarization phase and two new words (made up of the same syllables but in a novel order) until they lost interest. Infants spent more time listening to the new words, indicating that they had learned to identify the old words based on the transition probabilities.

The Role of Knowledge in Speech Perception

Our perception of speech is informed by expectations that we generate online given what we have experienced in the past (knowledge) probability of specific sequences of phonemes (phoneme transition probabilities)

Neural correlates of the probability of phoneme transitions in auditory cortex

The Role of Knowledge in Speech Perception

• Our perception of speech is informed by expectations that we generate online given what we have experienced in the past (knowledge)
• words that are expected in a particular situation
• termed phonemic restoration, we tend to perceive phonemes that are masked by noise (e.g., a cough) and in fact never uttered, but not phonemes that are actually missing (i.e., replaced with a brief moment of silence)
• similar to auditory perceptual completion, only driven by meaning
• modulated by visual information

This concludes the speech on speech

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