Speech Perception and Auditory Processing

Study Notes

Perception of Sounds

Frequency discrimination allows detection of differences in sound frequencies presented successively.
Temporal resolution enables recognition of two consecutive auditory events as separate.
Just-noticeable difference in sound intensity is about 5 dB, noticeable between specific vowel sounds like /i/ and /ɑ/.

Major Questions in Speech Perception

Understanding how humans comprehend speech in noisy environments involves several cognitive processes.
Key processes include identifying speech, recognizing meaningful units in acoustic signals, and translating these into meaning.

Acoustic Properties

Formants distinguish vowel sounds, while formant transitions help identify diphthongs and acoustic cues in stops.
Voice Onset Time (VOT) varies, with voiceless sounds having longer VOT than voiced counterparts.

Structure of the Auditory Pathway

Outer ear components (pinnae, external auditory meatus) collect and direct sound waves.
Middle ear includes ossicles and tympanic membrane, converting air vibrations into mechanical motion.
Inner ear (cochlea) processes frequency and intensity variations, aided by fluid wave motion.
Auditory pathway culminates in the central auditory nervous system (CANS), which facilitates sound discrimination, localization, and processing.

Speech Perception Cues

Visual cues combined with auditory cues enhance speech comprehension, influenced by individual knowledge (syntax, language familiarity).
Consistent cues in speech interpretations rely on memory spanning several segments, highlighting the importance of working memory.

Acoustic Variability and Co-articulation

Co-articulation leads to variations in acoustics, where the pronunciation of phonemes shifts based on surrounding sounds.
The acoustic signal shows high variability due to inter-speaker differences, intra-speaker inconsistencies, and contextual variations.

Categorical Perception

Categorical perception enables detection of distinctions between phonemes based solely on perceived categories (e.g., /p/ vs. /b/ at a VOT boundary).
Adults exhibit categorical perception tailored to the distinctions relevant in their native language.

Infant Speech Perception

Infants initially perceive a wide range of phonetic contrasts but gradually align their perception with their language environment by age one.
They begin to lose sensitivity toward contrasts unimportant in their primary language, emphasizing learning's role in perception refinement.

Conclusions on Speech and Categorical Perception

Individuals perceive phoneme categories rather than minute acoustic differences, reflecting a blend of auditory sensitivity and memory processes.
The interaction of speech and hearing evolution suggests that human auditory systems are specialized for processing speech sounds effectively.

Additional Considerations

Feature recognition informs phoneme understanding, with distinctiveness depending on the language.
Segmentation is vital in understanding continuous speech and involves the ability to interpret fluctuating acoustic information.
Challenges in segmentation arise from the lack of direct correspondence between phonemes and acoustic signals, highlighting the complexity of speech perception.

Key Points on Prosody

Speech prosody includes stress, intonation, and rhythm, which influence interpretation and emotional impact.
Effective processing of prosodic features aids in linguistically and emotionally interpreting spoken language.

Description

This quiz explores key concepts in speech perception and auditory processing, focusing on frequency discrimination, temporal resolution, and the understanding of speech in noisy environments. It examines the roles of formants and acoustic properties in distinguishing sounds and the structure of the auditory pathway.