SPEECH: Speech perception

Question 1

what does a spectrum show us?

Answer 1

how the energy is spread at different frequencies

Question 2

what does the auditory system show when speech or sound is produced?

Answer 2

the corresponding spectrum

Question 3

why can patients with a hearing loss confuse different vowels by thinking they sound the same?

Answer 3

-when you hear a vowel or any sound, your auditory system creates a spectrum that shows how energy is spread at different frequencies

-e.g. ‘a’ as in ‘father’ has a spectrum with a double peak at low frequency and a single peak at high frequency and ‘oo’ as in ‘pool’ has a similar double peak at low frequency but no peak at high so a patient with a high freq hearing loss is only gonna receive the first part of the spectrum and then the 2 vowels are gonna sound similar

Question 4

why might our auditory system have problems encoding physical features?

Answer 4

neurons responsible for either spectral or temporal processing is damaged for whatever reason, our auditory system will have issues encoding these physical features and the person will have issues with encoding

Question 5

what happens if someones auditory system is broken so their frequency analyser or basilar membrane is tron apart what happens?

Answer 5

the basilar membrane is the place where we have tonotopicity, we analyse frequency
then they might no be able to represent swift frequency changes efficiency or faithfully
AND
the person might have issues perceiving the sound

Question 6

explain the speech chain

Answer 6

1- The brain plans the articulatory gestures and contents (linguistic level) on the speaker’s side.

2 - Motor signals are sent to the speech production system (i.e., the respiratory, vocal folds, articulators, etc.) at the speaker’s physiological level.

3 - The speaker performs articulatory planning and execution (i.e., speech production).

4 - The articulated sound travels through air (acoustic levels) to be heard by both the speaker themselves and the listeners.

5 - The speaker and the listeners’ ASCENDING auditory systems process the acoustic features of the sound (the second physiological level at the listeners’ side), which is a bottom-up processing.

6 - The encoded sound information by the ascending auditory pathway is further interpreted at the cortical level, completing the goal of speech perception.

Question 7

how is speech perceived?

Answer 7

1) Speech production:
- At linguistic level: the speaker selects the words they are going to use.
- At the physiological & acoustic levels: they coordinate their muscles and articulators to generate and transmit a sound wave.

2) Speech perception
- The sound wave activates the hearing system in the ear and the brain where the listener then recognises what is being said

• And both are monitoring their own voices to make sure the sounds they produce are what they meant to produce

Question 8

what is bottom up processing?

Answer 8

Definition: Initial processing of incoming sounds, focusing on acoustic features.

Stages:
1) Sound: Creation of sound waves with acoustic information.

2) Hearing: Converting sound waves into neural signals.

3) Listening: Choosing relevant details with attention.

4) Comprehending: Understanding the meaning based on context and language.

5)Reacting: Storing in memory, reasoning, and generating responses.

In Ascending Auditory Pathway: Encoding of sound features for consistent perception.

Comparison: Usually less adaptable compared to higher-level cognitive processing

Question 9

what kind of analysis occurs with bottom up processing?

Answer 9

• In the auditory system, bottom-up processing involves analyzing both the timing and frequency of incoming sounds.

1) frequency analysis occurs through the tonotopic organization of the basilar membrane (BM). This analysis is then carried forward through various stages of the ascending central auditory pathway, including the auditory nerves, cochlear nucleus, inferior colliculus, and ultimately reaching the auditory cortex.

Question 10

whats the difference between a spectrogram and a cochleagram?

Answer 10

Spectrogram:
- Shows acoustic energy distribution over time and frequency.
- Utilizes Short-time Fourier transform (STFT).

Cochleagram:
- Depicts cochlear excitation patterns over time and frequency.
- Created using a model of the cochlea involving a gammatone filter bank, nonlinear compression, and half-wave rectification.

Question 11

what is the central auditory pathway?

Answer 11

Brainstem (CN, SOC, LL) → Midbrain (IC) → Thalamus (MGB) → Cortex (AC):

This sequence illustrates how auditory information travels from the brainstem through various nuclei to the cortex.

Question 12

what is the function and complexity of the central auditory pathway?

Answer 12

Function: Each nucleus specializes in processing different aspects of sound to ensure effective perception in various environments.

Complexity: While the specific functions of each nucleus are intricate, understanding them enhances comprehension of sensory and neural systems.

Question 13

what is top down processing?

Answer 13

Function: Top-down processing involves selecting, interpreting, and reacting to sensory information based on cognitive factors such as attention, memory, and reasoning.

1 - REACTING: It starts with reacting to sensory input based on stored memory and reasoning.

2 - COMPREHENDING: and interpreting the information using contextual, linguistic, and grammatical cues.

3 - LISTENING: attention and effort are directed towards selectively listening to specific information relevant to the task or context.

4 - HEARING: the acoustic signal is transduced into neural information for further processing.

Question 14

when the auditory system performs analysis and comparison, what kind of decisions does it make?

Answer 14

• Whether the phonemes are same or different (auditory discrimination)
• What phoneme did I hear (auditory identification)
• What is the sequence of appearance of these phonemes (form syllables, words, phrases, and sentences) (auditory comprehension)
• What is the speech if there is ambiguity in the incoming speech (bottom-up analysis plus or against top-down analysis)

Question 15

what is the auditory skill hierarchy for children?
*(In context of speech perception)

Answer 15

1- Auditory detection
Whether there is a sound
*Whether I can hear the speech

2- Auditory discrimination
Whether the two sounds are identical
*Whether two speech tokens are identical

3 - Auditory identification
Label the sound
*Which phoneme, syllable, word, etc. do I hear

4 - Auditory comprehension
What does the sound mean
*What is the meaning of the speech

Question 16

what is one important bottom-up auditory processing skill?

Answer 16

discrimination and identification of phonemic minimal pairs

Question 17

what is the motor theory of speech perception?

Answer 17

• According to the motor theory of speech perception, your brain doesn’t just process the sounds you hear.
• Instead, it interprets those sounds by mentally simulating the movements needed to produce them.
• So, when you hear a word like “hello,” your brain doesn’t just recognize the sound “h-e-l-l-o.”
• It also imagines the specific movements the speaker’s tongue, lips, and vocal cords make to produce those sounds.
• This theory suggests that we understand speech not only through what we hear but also by mentally simulating the physical actions involved in producing speech.

Question 18

what is the McGurk effect?

Answer 18

The McGurk effect is an auditory illusion where perception of speech sounds is influenced by visual information. Despite hearing one sound, when paired with seeing a different mouth movement, people often perceive a third sound. This highlights how our brain integrates information from multiple senses to understand the world.

Question 19

what is General auditory (GA) and learning approaches?

Answer 19

The General Auditory (GA) and learning approaches suggest that the brain doesn’t necessarily rely on recovering specific motor or articulatory gestures to perceive speech. Instead, it’s proposed that listeners use various acoustic cues to categorize speech sounds, even if those cues are imperfect. This implies that listeners are adept at interpreting speech based on overall patterns in sound, rather than precise articulatory details

Question 20

what is categorical perception?

Answer 20

Definition: The categorization of speech sounds into distinct groups with clear boundaries.

Key Features:
Clear Boundaries: Listeners sharply distinguish between different speech sounds, with distinct boundaries separating one sound from another.
Discrimination Accuracy: Listeners accurately differentiate between sounds on opposite sides of boundaries but struggle within the same category.

Examples: Changes in vowel formants or consonant timing demonstrate this phenomenon

Question 21

what is the picket fence effect in speech?

Answer 21

• Definition: Also called ‘dip-listening’, it’s recognizing speech by using gaps in fluctuating noise.
• Explanation: Listeners catch speech snippets during low-noise moments to understand the overall content.
• Significance: Demonstrates reliance on linguistic cues and context for understanding in noisy environments.

Question 22

what is temporal resolution?

Answer 22

ability to precisely encode, represent, or perceive the amplitude fluctuations of sound over time.

Question 23

how can amplitude fluctuation over time be viewed?

Answer 23

• Temporal resolution
• Rapid fluctuation: called ‘(temporal) fine structures’
• Slow, overall fluctuation: called ‘(temporal) envelopes’

Question 24

What does the auditory perception of spectral features entail?

Answer 24

It involves how the auditory system interprets characteristics like amplitude peaks, peak width, troughs, harmonic separation, and spectral contrast in sounds.