What is auditory perception?
- Gives us information of sounds
Where?
What type of sound? - Can seem a bit unreliable
What is sound?
Soundwaves in air, water or some other conducting medium
Frequency
- Gives perception of pitch
- Number of soundwaves/seconds
- Hertz
- Most sounds are in lower frequency
Amplitude
- Perception of loudness (heigh of soundwave)
- Decibels
Increase of 10 dB gives an increase of tenfold
Purity
- Perception of timbre
Quality, how we distinct different instrument from each others
Musical tones
Patterns and series of different frequencies
- Irregular frequencies gives noise
- Different sounds has different patterns
What are sine waves?
Can be seen as building blocks for more complex sounds
- Different intensity gives different qualities
- Each sound is composed of a fundamental frequency and harmonics at multiple fundamental frequency
Fourier’s theorem
With sufficient number of sine waves, any sound can be created
Fourier analysis
More complex sounds can be broken down into sine wave tones
Phonemes
The basic sounds that compose a language
- Same letter can have a different sounding phoneme - Different physical characteristics
k vs c
Phonology
The sounds of language and the rule system for combining them
Typology of phonemes
Consonants
1.Placement of articulation
2. Manner of articulation
3. Voicing
Vocals
1. Placement in the mouth
2. Tongue position
Speech perception
- Different language sounds differently
- We hear other languages as a long string of sounds, ours is more divided - called categorical perception
- Speech change constantly
Alot of factors affect speech
Coarticulation
More than one sound is articulated at the same time, not one phoneme at a time
Problem of invariance - Speech
Same sound can be different
- Still understand speech
Whispering
- Invariant=Never changing
Cool vs Keep
- Both processes involved
Motor theory of speech perception
Perceive language by comparing sounds to how you would pronounce it
- Estimating and expectations
Sound spectogram
Graphic representation of sounds
- To see how different syllabus can be diferent or similar
- Important for meaning to the words
How do we perceive sound?
Sound waves gets translated into nerve impulses and through the auditory nerve, both hemispheres gets the message
- Outer ear gather the sound waves, starts vibrating
- Middle ear starts to move due to vibrations
3- In the inner ear, fluids in the cochlea starts to move, sending nerve impulses to the brain
How does coding of intensity work?
- High amplitude sound waves cause the hair cells to bend more, resulting in higher firing rate within auditory nerve
- Some hair cells are specialized, only react to high amplitude sound waves
When is something too loud for humans?
At 85 dB, for longer periods of exposure
- Vaccum cleaner
- Proximity also matters
Conductive hearing loss
Damage to the mechanical system that conducts sound waves to the cochlea
- Outer and middle ear damages
- Capacity to transmit vibrations can be affected
Sensorimotor hearing loss
Damage to the chochlea’s receptor cells or the auditory nerve
- Inner ear damages
- Hearing aids cant help
- Due to illness, age, extended or repeated exposure to lound sounds
How does coding of pitch work?
There are 2 theories about that
- Frequency Theory (lower frequencies(
- Place Theory (higher frequencies)
Modern take is a combination of both of them
Frequency Theory
Perception of pitch depends on the rate of vibration of the basilar membrane
- Firing rate neurons matches the frequency of the sound wave
- Max of 4k Hz
- Neurons has a limited firing rate
