lecture 2 - phonological development Flashcards
why is development exciting?
- Theory, technology, computational modelling,
machine learning… - Not just about studying children
Language (development)
Why should you care?
– Fascinating
* Complexity of human development
– Important
* Practitioners (often difficulties in disorders)
* Impact beyond psychology (e.g., machine learning)
– Many of us are likely to be parents…
Language - linguistics
semantics - the study of meaning
syntax - the study of word order
phonology - the study of how sounds are used within a language
phonetics - the study of raw sounds
pragmatics - the study of language use
linguistics - morphology
the study of words and word formation
inflectional morphology - concerned with changes to a word that do not alter its underlying meaning
derivational morphology - concerned with changes to a word that alters it underlying meaning
Why language acquisition should be hard?
- Infants learn language from listening to
people speak
Problems: - Speech is continuous, not segmented into
words → SEGMENTATION problem - Different auditory signals should be perceived
as the same sound → LACK OF
INVARIANCE - Each speaker sounds a bit different →
SPEAKER VARIABILITY
Speech is sound
Sound = waves of increases and decreases in air pressure
ripples in the air
diagrams in the notes
Speech is a special kind of sound
- Not just one wave - speech composed
of waves of many different frequencies - Each wave has its own energy level - corresponds to sound loudness
- Ear decomposes the sound wave into
frequencies and energies
– Spectrogram
speech spectrogram is in notes
How do adult listeners
make sense of speech?
- Despite the fact that speech is continuous and
variable, listeners perceive it as composed of
discrete sounds. - Each language has a fixed inventory of these
discrete sounds, called phonemes. - We can demonstrate that listeners perceive
phonemes (despite the variability) using
phoneme identification tasks.
Phoneme identification
Sounds differ in Voice Onset Time (VOT)
Long VOT → /k/
Short VOT → /g/
Clear – 95 ms VOT - long VOT
…
Glear– 11 ms VOT - short VOT
diagram in notes
word bias - ganong 1980
phoneme identification helps adults make sense out of speech
GISS-KISS
GIVE-KIV
diagram In notes
adults are good at taking context into account
phoneme restoration
(Warren, 1970)
“It was found that the *eel was on the…
axle / table / fishing rod / orange.”
Perceive wheel, meal, reel, or peel
Which sound was missing?
When did the cough occur?
how do infants learn phonemes
- Before we can answer this question, we
need to answer another one… - How can we know what infants know
about phonemes? - After all, we cannot ask them to tell us
what they are hearing…
we use high amplitude sucking - diagram in notes
newborn language discrimination
mehler et al 1988
high amplitude sucking
if french changed rate of sucking when heard French then Russian but not English then Italian as not familiar with either language
if American changed rate of sucking when switched from English and Italian but not French to Russian as not familiar with either language
Prenatal language perception?
- 4 months before birth
- Low frequencies
- Rhythms and prosody
phoneme perception
korean-speaking adults vs Korean newborns
adults can tell the difference between da and ta not ra and la
newborns can tell the difference between both ra and la and da and ta
conditioned head turn
werker and Lalonde 1988
discrimination of alveolar /da/ and retroflex /Da/
if speak English can distinguish difference at age 7 months not 12 months or adult
if speak Hindi can distinguish at 7 months, 12 months and as an adult as its a meaningful contrast in their language
perception of phonemes
newborn/ young age - ability to describe non-native phonemes
as get older non-native language phonetic abilities decrease only know native phonetic contrasts it gets better with age
adults - non-native phonetic discrimination = very difficult
study graph in notes - kuhl et al 2006
turning into language
turning into the world around - perceptual narrowing
narrows from 6/9 months to adult
pascalis et al 2002
diagram in notes
neural plasticity
Humans are born particularly early in development
Allows for tuning and shaping of neural circuitry in interaction
with the environment
neural commitment
(Kuhl, 2004; Kuhl et al., 2008)
* Initial native language learning
– Neural commitment
* Brain across development
Specialized
Committed to their native language
graph in notes
summary
- Speech perception is hard because of
– Lack of segmentation
– Lack of invariance
– Speaker variability - Infants gradually tune in to the speech
sounds of the language(s) being spoken
around them. - Methods for studying language development
need to be age-appropriate
how to describe speech sounds
- Acoustics is the name of the study of the physical properties of sounds. Acoustic info about sounds can be depicted in a number of ways eg most commonly a sound spectrogram
sound spectrogram
shows the amount of energy present in a sound when frequency is plotted against time. The peaks of energy at particular frequencies are called formants which is an important characteristic of speech sounds. All vowels and some constants have formants but the patten of formants is particularly important in distinguishing vowels.
we can describe the sounds of speech at two levels
phonetics = acoustic detail of speech sounds (physical properties) and how they are articulated. study of phones
phonology = sound categories each language uses to divide up the space of possible sounds. study of phonemes