Lecture 23

Question 1

Describe formants and sound spectrograms

Answer 1

• The formant with the lowest frequency is
  called the first formant (F1), the second
  formant (F2) is the next highest, etc.
• These can be visualized using sound
  spectrograms

Question 2

Describe consonants

Answer 2

Consonants are produced by
constrictions of the vocal tract

Question 3

Describe formant transitions

Answer 3

rapid changes
in frequency preceding or following
consonants

Question 4

Describe phonemes

Answer 4

any of the perceptually distinct units of sound in a specified
language that distinguish one word from another, for example p, b, d, and t in
the English words pad, pat, bad, and bat.

Question 5

Describe morphemes

Answer 5

a meaningful morphological unit of a language that cannot be
further divided (e.g. the word ‘dog’ cannot be broken down any more than it
already is)

Question 6

Describe lack of invariance

Answer 6

While words are ‘built’ by putting together phonemes in different
combinations, the acoustic signal produced for any given phoneme is variable

Question 7

Why is the lack of invariance important?

Answer 7

perceptual constancies (e.g.
colour constancy, size constancy, etc.), our perceptual systems can still
recognize differing acoustic signals as representing the same phoneme

Question 8

Describe coarticulation

Answer 8

• The sounds produced by a single phoneme can be different depending on what phoneme
  comes before and after it

Question 9

Describe categorical perception

Answer 9

• Categorical perception occurs
  with speech, given that a wide
  range of acoustic cues results in
  the perception of a limited
  number of sound categories

Question 10

Describe voice onset time

Answer 10

the delay between
when a speech sound begins and when the vocal cords start vibrating

Question 11

Describe the McGurk effect

Answer 11

speech perception can be influenced
by multimodal integration

• Visual information provided is one
  such influence (and can be referred
  to as ‘audiovisual speech
  perception’)
• The McGurk Effect was introduced
  in our very first lecture and involves
  visual input changing speech
  perception

Question 12

Describe Kriegstein et. al study

Answer 12

• Kriegstein (2005) presented participants with
  stimuli using both familiar and unfamiliar voices,
  while using fMRI
• The superior temporal sulcus (STS) was found
  to be activated for all speech stimuli (consistent
  with prior work associating it with speech
  perception), though familiar (but not unfamiliar)
  voices also activated the fusiform face area
  (FFA)
• Provides a physiological basis for a link between
  speech perception and facial processing

Question 13

Describe phoneme perception

Answer 13

• Phonemes are more easily perceived when
  they appear in a meaningful context
• Represents an influence of top-down
  perception
• Rubin et al. (1976): Participants recognized
  phonemes more quickly when presented as
  part of real words, as compared to ‘nonsense’
  words (e.g. bat vs. baf)

Question 14

Describe the phonemic restoration effect

Answer 14

• Missing phonemes can also be ‘filled in’ based on expectations (the
  phonemic restoration effect)
• Warren (1970): embedded a cough in a recording of a sentence and asked
  participants to report: 1: where in the sentence the cough occurred, and 2:
  where any phonemes were missing
• Participants could not accurately place where the cough occurred, nor
  recognize the missing phoneme that was removed

Question 15

Describe the Millard and Isard study

Answer 15

• Miller and Isard (1963) asked participants to ‘shadow’ (listen with
  headphones and repeat aloud what is heard) three kinds of sentences:
  1. Grammatically correct sentences
  e.g. gadgets simplify work around the house
  2. Anomalous sentences that correctly follow grammatical rules but do not
  make sense
  e.g. gadgets kill passengers from the eyes
  3. Ungrammatical strings of words
  e.g. between gadgets highways passengers the steal

Question 16

Describe the segmentation problem

Answer 16

• The segmentation problem refers to the fact that, because there are no physical
  breaks in the continuous acoustic signal, speech segmentation (perceiving
  individual words) can be a challenge

Question 17

Describe transitional probability

Answer 17

The chance that one sound will follow another in a language

Question 18

How do we learn a language?

Answer 18

• A (very) general example of this would be that English speakers expect at
  least one vowel to occur after every few consonants or so
• We learn these associations implicitly, through statistical learning

Question 19

Describe the Davis study

Answer 19

• Davis et al. (2005) used noice-vocoded speech (a
  method to add noise to an acoustic signal) and asked
  participants to identity the words they were perceiving in
  each sentence
• Accuracy was close to 0% for the first sentence and
  gradually increases across sentence number
• Additional information provided by the preceding
  sentences provides some context and can lead to pop-
  out effects, in which related words in later sentences are
  easier to identify
• Speaks to the role of top-down processing in perceiving
  language

Question 20

Describe motor theory

Answer 20

• Although it has largely fallen ‘out of fashion’, Liberman et al. (1963, 1967) proposed a motor
  theory of speech perception
• This was partly developed as a response to the lack of invariance (or, in simpler terms, the
  presence of variability!) associated with phonemes contained with the acoustic signal
• Remember that mouth movements involve changing the configuration of your articulators
  (e.g. tongues, lips, etc.), which modify the shape of the vocal tract and therefore change its
  resonance properties (which affect frequencies, etc.), which accomplishes the task of
  producing different sounds of speech when air is pushed through it

Question 21

What is important about model networks?

Answer 21

• Note that some models consider networks supporting production and
  comprehension as separate (diagram on the left), others as a unified
  network (diagram on the right) (Schomers & Pulvermuller, 2016)

Question 22

Describe Broca’s aphasia

Answer 22

Broca’s aphasia results from damage to Broca’s area (in the frontal lobe)

Question 23

Describe Wernicke’s aphasia

Answer 23

results from damage in Wernicke’s area (in the temporal lobe)

Question 24

What is word deafness?

Answer 24

(inability to recognize
words)

Question 25

Describe the voice area

Answer 25

A ‘voice area’ in the superior temporal sulcus (STS) has been identified that
is activated more strongly by voices than other sounds

Question 26

Describe voice cells

Answer 26

‘Voice cells’ in the temporal lobe of monkeys have also been found which
respond more strongly to recordings of monkey calls than to calls of other
animals (Perrodin et al., 2011)

Question 27

Describe phonetic features

Answer 27

• Some of the neurons identified in Mesgarani et al. (2014)
  also seem tuned to selectively respond to more general
  phonetic features, such as:
• Manner of articulation: what you actually do with your articulators (how you move your tongue, lips, etc. when pronouncing certain phonemes)
• Place of articulation: where in your mouth the
  articulators are manipulated (back of the throat, front of mouth close to teeth, etc.)

Question 28

Describe the dual stream model of speech perception

Answer 28

• The dual stream model of speech perception proposes that the ventral and
  dorsal pathways are involved with identifying sounds of speech and
  representing movements associated with sounds of sounds, respectively

Question 29

Describe Eimas study

Answer 29

• Eimas et al. (1971): tested habituation
  with different VOT’s using suckling
  (rather than looking) time
• After habituating to a baseline
  phoneme, the infants dishabituate to
  one kind of change (that adults would
  perceive as being a different
  phoneme) but not another (that
  adults would not perceive as being a
  different phoneme)

Question 30

Describe the social gating hypothesis

Answer 30

The social gating hypothesis proposes that
our brain ‘gates’ specific mechanisms that are
important/required for speaking particular
languages