Problem 9 Flashcards
Acoustic signal
Refers to the patterns of pressure changes in the air
–> created by air that is pushed from the lungs past vocal cords and into the vocal tract
Articulators
Structures including the
a) tongue
b) lips
c) teeth
d) jaw
e) soft palate
–> movement of theses structures alters the shape of the vocal tract
Vowels
Vowels are produced by the vibration of the vocal cords
- -> some vowels have more than one pronunciation
- -> there are more vowel sounds than letters !
ex.: “e” sounds different in “head” and “heed”
Formants
Frequency peaks due to resonance of the vocal tract
- -> our voice produces an infinite number of formants
- -> formants 1+2 are responsible for vowel sounds
- -> each vowel sound has a characteristic series of formants
Sound spectrogram
Indicates the pattern of frequencies and intensities over time that make up the acoustic signal
How are consonants produced ?
Consonants are produced by a constriction or closing of the vocal tract
Formant transitions
Refer tp rapid shifts in frequency preceding or following formants
–> associated with consonants
ex: “read”
Phoneme
Refers to the shortest segment of speech that, if changed, would change the meaning of a word
–> are defined in therms of the sounds that are used to create words in a specific language
Coarticulation
The fact that the pronunciation of a sound in a word is affected by the sounds before and after it
ex.: “boot” vs “bat”
–> even though “b” is the same in both words, one articulates each differently
Why is coarticulation an example for perceptual constancy ?
Because be perceive the sound of a phoneme as the same even though the acoustic signal is changed by coarticulation
Why might different speakers have different acoustic signals for the same phoneme or word ?
a) slow or fast speech
b) high or low pitched voice
c) sloppy pronunciation
- -> all of these variabilities are reflected in spectrograms
- -> listeners must transform this info into familiar words
Categorical perception
Occurs when stimuli that exist along a continuum are perceived as divided into discrete categories
Voice onset time
VOT
Refers to the time delay between when a sound begins and when the vocal cords begin vibrating
–> property that helps us divide phonemes into discrete categories
Phonetic boundary
The point along the continuum in which the perception of speech sound changes from one category to another.
–> ex.: change form “da” to “ta”
Why is phonetic boundary an example of perceptual constancy ?
Because all the stimuli on the same side of the phonetic boundary are perceived as the same category
–> this simplifies our perception of phonemes
Why is our speech perception “multimodal” ?
Because it can be influenced by information from a number of different senses
McGurk effect/
Audiovisual speech perception
Although auditory information is the major source of information for speech perception, visual information can also exert a strong influence on what we hear
Which cortical areas are activated when perceiving speech ?
Auditory cortex: lipreading
Superior temporal sulcus: Speech perception
Phonemic restoration effect
Under certain conditions, sounds actually missing from a speech signal can be restored by the brain and may appear to be heard
- -> meaningfulness makes it easier to perceive words
- -> knowledge of grammar enhances effect
Speech segmentation
Perception of individual words in a conversation
–> meaning + prior knowledge are responsible for organizing sounds
Transitional probabilities
Describe the chances that one sound will follow another sound
Statistical learning
The process of learning about transitional probabilities + about other characteristics of language
Indexical Characteristics
Taking in characteristics of the speakers voice
–> carries information about the speakers
a) gender
b) age
c) place of origin
d) emotional state
e) being sarcastic or serious
Aphasia
Inability (or impaired ability) to understand or produce speech, as a result of brain damage
Brocas aphasia
Labored + stilted speech
–> only able to speak in short sentences
BUT: still capable of comprehension
Wernickes aphasia
- Extremely disorganized + meaningless speech
- Difficulty understanding what others say
BUT: fluent speech
Motor theory of speech perception
- Hearing a particular speech sound activates motor mechanisms controlling the movement of the articulators
- Activation of these motor mechanisms activates additional mechanisms that enable us to perceive the sound
Dual streams model
We use the ventral + dorsal pathways to perceive sounds
ventral –> gives a sound a meaning
dorsal –> sounds into movement
