Instrumentation Flashcards
Neurophysiologic Development
Infant auditory sensitivity seems to be especially tuned to sounds distinctive in human speech
During babbling, the infant demonstrates sensitivity to intonation patterns of other speakers by mimicking them
Whitaker theorizes that the connections between Wernicke’s area and Broca’s area are activated when babbling temporarily ceases.
When first words arrive at 1 year of age, the child has been sensitized to the particular language and dialect of a community
Critical Period for Language Development
Important in the neurophysiology of speech perception
Applies to both perception and production
Most researchers agree that the critical period extends to puberty
Easier to learn a language before puberty
Cerebral lateralization is thought to be complete by puberty
Language Lateralization
It is believed that dominance for speech in the left hemisphere is set at an early age – 4 yrs of age
Puberty is set as an outer limit
The younger the child, the more malleable the neural correlates of language learning
The neural flexibility during the youthful critical period allows children to compensate by establishing a linguistic center in an undamaged are of the brain
Adults have little flexibility to do this
Motor Theory of Speech Perception
This theory posts a link between speech perception and speech production
The listener must extract information about articulation from the acoustic signal
Auditory Theory of Speech Perception
Uses the hearing mechanism and perceptual processing used for any other type of sound
The listener identifies acoustic patterns or features and matches them directly to the learned and stored acoustic-phonetic features of the language
Computer as a Research Tool
Has become pervasive in speech research
Used for
Acoustic analysis
Transform any analog signal and put into graphic displays and measure
Air pressure
Articulator movement
Brain waves
Muscle contraction
They are used to:
Average data
Measure reaction times
Record frequencies of occurrence of observed events
Provide a permanent store of data and results
Acoustic Analysis of Speech Production
The essence of acoustic analysis of speech is the conversion of sound waves to visual representations that be inspected, measured in various ways, and related to the articulatory gestures that produced them
Waveform Analysis
Useful for making acoustic measurements and displaying and measuring the output physiologic devices (e.g.: variations in air pressure, movements of the articulators, brain waves, etc.)
Waveform analysis is an interference pattern
The sum of many frequencies with different amplitudes and phase relations
Difficult to specify component frequencies from a waveform alone – spectral analysis is used for this
Spectral Analysis
Spectrogram can depict the rapid variations in the acoustic signal that characterize speech
Spectrogram provides an analysis of the frequency components of the acoustic signal in terms of its harmonics or its peaks of resonance (formants).
Narrowband Spectrogram
used for representing the harmonics of the glottal source
Darker bands represent the harmonics closest to peaks of resonance in the vocal tract
Lighter bands represent harmonics whose frequencies are further from the resonance peaks
Good for assessing intonation
Each spectral snapshots are of sections about 20 ms
Wideband Spectrogram
used more when studying phonetics
See changes in the resonances of the vocal tract – formant frequencies
Each spectral snapshot are of sections about 3 ms in length
