Templates
- Outdated
Language dont sound the same
There are dialects
Problem of invariance - Matching with mental templates
Use of pre-existing knowledge and memory
Feature detection
- Succesful
Problem of neglecting context
Conceptual Driven processing
2 examples on why context matters
- Words at a part vs isolation
- Speech where one letter in a word is missing
What happens when there is multiple, concurrent sounds?
- What should we focus on?
Cocktail party problem - Segregating different sounds into a meaning
Auditory stream segregation
A perceptual process by which the human auditory system groups sounds from different sources into perceptually meaningful elements
- Galloping sound
- Increased sound rate you start hearing two sounds
Auditory scene analysis
Our ability to segregate and intergrate individual sounds relative to their sources
- Gestalt-like baic principles of grouping
When hearing sounds we tend to group acoustic components that
*similar across time
*are harmonically related
Auditory Scene analysis - Problems
- Which frequencies are present in the sound signal and come from the same source?
- Sound stream
A source producing discrete sounds over time (footsteps) - Very bottom-up process
Context gives familiarity with certain sounds
Bistable sound illusions
Analogue to reversibility figures in vision, hearing something in two different ways
- Galloping sound
Perception can change for the same melody
- Rapid sequence of repeated syllables or words
How can locate sounds?
Often from binaural hearing
We use both of our ears, sounds rarely comes directly in front of us
Often listen to the pitch to figure out where the source is from
- Survival insticts
Interaural time difference*
Sounds arrive first at ear closest to the sound
- Low Hz
Interaural intensity difference*
Sounds are loudest at ear closest to the sound
- High Hz
How do we recognize sounds?
- Often by pitch
Subtle changes - Different languages has different pitches
How do we recognize speech sounds?
Phoneme categories
Dialetcts, certain phonemes overlap
- Categorical perception
- Invariance problem
- Context matters
State of the person changes perception as well
What can some spectrograms illustrate?
That two phonemes can be categorized as the same despite physical differences
Mismatch Negativity
- Violation of expectations in a sequence of sounds
One sound deviates from the rest
Brain loves expectations
The interaural level difference
Difference in loudness and frequency distribution between the two ears
