W18- Speech Perception

What is the central argument of modern theories of speech perception?

Speech perception is an active process involving auditory, motor, cognitive and multisensory systems rather than passive hearing.

What is tonotopic organisation?

Systematic mapping of sound frequency across the auditory system.

What frequencies are represented at the base of the cochlea?

High frequencies.

What frequencies are represented at the apex of the cochlea?

Low frequencies.

What is the function of inner hair cells?

Convert mechanical vibrations into neural activity.

What is the function of outer hair cells?

Amplify and fine-tune cochlear responses.

Why is cochlear tonotopy important for speech perception?

It separates complex speech sounds into different frequencies for processing.

Where is primary auditory cortex located?

Heschl's gyrus (BA41/42).

What is preserved from cochlea to auditory cortex?

Tonotopic organisation.

According to Hickok & Poeppel (2007), is speech perception localised or distributed?

Distributed across temporal, frontal and motor regions.

What role does the superior temporal gyrus play in speech perception?

Processing speech sounds and auditory representations.

What role does the inferior frontal gyrus play in speech perception?

Higher-order linguistic processing and prediction.

What is sine-wave speech?

A degraded speech stimulus initially heard as whistles until listeners recognise it as speech.

Why is sine-wave speech important?

It demonstrates the role of top-down processing in perception.

What does sine-wave speech show about speech perception?

Perception depends on expectations and prior knowledge.

What is predictive coding?

A model proposing that perception results from interactions between sensory input and top-down predictions.

What is bottom-up processing?

Perception driven by incoming sensory information.

What is top-down processing?

Perception influenced by expectations, knowledge and predictions.

How does predictive coding explain understanding unfamiliar accents?

The brain learns patterns and generates increasingly accurate predictions.

What percentage of adults over 70 experience hearing loss?

Approximately 80%.

Why does age-related hearing loss affect speech perception?

Important speech frequencies become difficult to detect.

What happens when high-frequency speech information is lost?

The brain must infer missing information from context.

What is the Information Degradation Hypothesis?

Hearing loss increases listening effort, consuming cognitive resources.

What cognitive functions may be affected according to the Information Degradation Hypothesis?

Attention, working memory and executive function.

What is a strength of the Information Degradation Hypothesis?

It explains increased cognitive effort during listening.

What is a limitation of the Information Degradation Hypothesis?

It does not fully explain structural brain changes.

What is the Sensory Deprivation Hypothesis?

Reduced auditory stimulation causes neural underuse and atrophy.

How does the Sensory Deprivation Hypothesis explain cognitive decline?

Less auditory input leads to long-term changes in brain structure and function.

What additional factors may link hearing loss and dementia?

Loneliness, depression and social isolation.

Does hearing loss cause dementia?

Current evidence is correlational; causation remains unproven.

What is a key essay evaluation regarding hearing loss and dementia?

Both Information Degradation and Sensory Deprivation may contribute simultaneously.

What is multisensory integration?

The combination of information from multiple sensory modalities.

What is the Temporal Binding Window (TBW)?

The time period during which sensory events are likely to be integrated.

What is the McGurk Effect?

Audiovisual speech illusion where visual information alters perceived speech sounds.

Why is the McGurk Effect important?

It demonstrates that speech perception is fundamentally multisensory.

How does ageing affect the Temporal Binding Window?

Older adults have wider TBWs.

What is one benefit of wider TBWs in ageing?

Greater use of visual information to compensate for hearing loss.

What is one cost of wider TBWs in ageing?

Greater susceptibility to multisensory illusions.

Which brain region is considered a major hub for audiovisual speech integration?

Superior temporal sulcus (STS).

What is the strongest overall conclusion from Lecture 1?

Speech perception is an active, predictive and multisensory process supported by distributed neural systems.