Speech Perception

Phoneme - a basic unit of a speech sound that distinguishes one word from another

Phonemes do not have meaning on their own but they distinguish one word from another and combine to form syllables and words.

For example, the initial phoneme in the word 'bat' distinguishes it from the word 'pat'.

Speech spectrogram - a display that shows the amount of energy present at different frequencies during the time course of a speech stimulus.

Formants - concentrated acoustic energy - characteristic of vowels - change with changes in mouth posture and airflow pattern

The first two formants for a series of vowel sounds made by an adult male voice and one sound made by a child

Consonants are generally indicated by changes in formants over short intervals of time called formant transitions

Changes in the formant transition causes a systematic change in the consonantal sound heard for the same vowel

The rate of change in formant transition is also important in the perception of phonemes

The same consonant can be heard despite the fact that the formant transition in the second formant changes from a rise to a drop depending on the vowel

Voice onset time (VOT) - time between the release burst and the onset of periodic pulsing of the vocal folds or voicing (articulatory definition)

Two aspects of categorical perception

1) categorization (we perceive stimuli in categories)

2) discrimination (we can readily discriminate stimuli between categories but not within)

McGurk Effect

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