Lecture Week 3 Flashcards
1
Q
Auditory Sense of Self
A
- Sense of Sound contributes to our sense of self
- Playing sounds of a certain heart rate; if a person thinks that is their own heart rate then their own heart rate will change to match the recording.
2
Q
Physical Definition of Sound
A
- Pressure changes in the air or other medium
- Could also be pressure change in water, a gas or a solid
3
Q
Perceptual Definition of sound
A
- The experience we have when we hear.
4
Q
How is sound created?
A
- Sounds are created when objects vibrate
- Vibrations cause the surrounding air to change pressure
- The type of pressure change determines the type of sound wave
- The sound wave determines what we hear
5
Q
Amplitude Waves
A
- The Level of loudness of a sound
- Objects that vibrate a lot will be perceived as loud
- Measured in Decibels dB
6
Q
Frequency Waves
A
- The number of times per second that a sound wave repeats the pattern of pressure
- The number of times the waves go up and down per second
- Measured as Hz - Hertz
- Perceived as pitch; High frequency is high pitch and low frequency is low pitch
7
Q
High Risk and Pain Threshold in Human Hearing
A
- At around 115 dBs we begin to experience sound that may cause us damage.
- At around 135 dBs our nociceptors will begin to transduce and we will experience pain.
- This is about equivalent to the sound of a gun going off next to your ear.
8
Q
Hyperacusis
A
The hearing condition with lingering pain
9
Q
Psychological Interpretation of Sound - Loudness
A
- How we experience sound of a particular amplitude
- High amplitude is loud
- Low amplitude is quiet
10
Q
Psychological Interpretation of Sound - Pitch
A
- Our experience of sound related as a frequency
- High frequency, High pitch, High Hertz
- Low frequency, Low pitch, Low Hertz
11
Q
Psychological Interpretation of Sound - Timbre
A
- The ability to judge two sounds with the same amplitude and frequency as being different from one another
- Like the flavour of the music and not the taste
eg: the same note being played by a piano and a guitar
12
Q
Outer Ear
A
- Also called Pinnae are first point of contact of sound from the environment
- Only Mammals have outer ears
- Some mammals do not have pinnae such as seals and Walruses
- They funnel sound into the ear canal
13
Q
Ear Canal
A
- Insulates and protects the tympanic membrane
- Also funnels sound and serves to amplify some frequencies
14
Q
Tympanic Membrane
A
- Also called the Ear Drum
- A barrier between outer ear and middle ear
- It is made of thin skin so if it is damaged it will repair like any other peice skin
- Vibrates in response to fluctuations in air pressure
- When it vibrates it moves the bones in the inner ear
15
Q
Middle Ear
A
- Consists of three very small bone called ossicles
- Malleus
- Incus
- Stapes
- Two small muscles
- Tympanus Muscle
- Stapedius Muscle
16
Q
Ossicles
A
- Purpose of Ossicles is to amplify sounds
- Smallest Bones in the Human Body
- Malleus
- Incus
- Stapes
- Ossicle amplicifaction is essential for hearing faint sounds they amplify sound x18
17
Q
Malleus Ossicle
A
- Is connected to the Tympanic Membrane
- It moves when the Tympanic Membrane moves
- They move each other around in response to flucutations in air pressure
- They operate like levers
- Ossicle amplicifaction is essential for hearing faint sounds they amplify sound x18
18
Q
Tensor Tympanic Muscle & Stapedius muscle
A
- Decrease Ossicle vibration when tensed
- They protect our ears from loud noises
- When they tense they hold the ossicles stable so they dont amplify sound
- Fast responding by 1/5 of a second
19
Q
Inner Ear
A
- Transduces responses to air pressure changes into neural signals to be processed as sounds
20
Q
Cochlea
A
- Contains the vestibular organs
- Organ of Corti
- semi circular canals
- Otolithic Organs
- Filled with watery cochlear fluid in all the canals
- When the ossicles vibrate this causes the cochlear fluid to vibrate as well
- This movement affects the:
- Basilar Membrane
- Tectorial Membrane
21
Q
Organ of Corti
A
- Responsivbe for transducing changes in air pressure into neural activity
22
Q
Basilar Membrane
A
- Where the Stereocilia are located
- This is specifically where the hair cells begin the process of transduction
- Hair cells respond to the movement in the cochlear fluid
23
Q
Tectorial Membrane
A
- A gelatinous structure that extends into the midde canal of the ear
- It causes the hair cells to fluctuate and it depends on how the hair cells move on what type of signals get transduced
- This movement is called Tectorial Shearing.
24
Q
Pitch and the Basilar Membrane
A
- Different parts of the cochlear are sensitive to different types of ptch
- This is because the cochlear is wider at one end than the other
- This changes the way the hair cells can bend or change the amount of stimulation they need to bend
25
Cochlear Nucleus
* The first brain stems nucleus at which afferent auditory nerve fibres synapse
* Then sends neural activity to the Superior Olive
26
Superior Olive
* Region of the brain stem where auditory input is received
* The first place where inputs from both ears are received
* Intergrates information so we can quickly locate where a sound is coming from
27
Inferior Colliculus
* Also important for Binaural Integration
* In the midbrain nucleus
* Then sends information to the Medial Geniculate Nuclesu of the Thalamus
28
Binaural Integration
Integrate and process neural information from both ears
29
Medial Geniculate Nuclesu of the Thalamus
* Thalamus is the relay station for all of our senses
* MGN sends auditory signals to the temporal cortex
* MGN receives signals from auditory cortex
* Information from both ears are processed here on both sides
30
Primary Auditory Cortex (A1)
* In the temporal lobe
* Sends information on to the belt area and parabelt area
* Responsible for acoustic organisation
31
Belt Area
* A region of the A1 Cortex
* Directly adjacent to the A1
* where neurons respond to more complex characteristics of sounds
32
Parabelt Area
* Lateral and Adjacent to the Belt Area
* Where neurons respons to more complex sounds as well as inputs from other senses
33
Left-Right Localisation
* Interaural Time Differences
* Interaural Level Differences
34
Azimuth
* The angle of a sound source on the horizon relative to a point in the centre of the head
* Anything that happens 360O on the Horizon is called Azimuth
* To work out where things are on the Azimuth we can use our ITDs and ILD's
* We can also disambiguate using the shape of our Pinnae
35
Disambiguate in Hearing
* Remove uncertainty about sound using both ears to detect differences on the Azimuth
36
Interaural Time Differences
* The difference in time between a sound arriving in one ear over the other depends on which ear the sound is closest to.
* If a sound is straight ahead or straight behind the ITD will be 0
* If it is directly at either side it will be maximum ITD
* It is slightly easier to hear sounds from the front because the shape of our Pinnae
37
Medial Superior Olive
* Interaural Time Differences are processed here
* Happens from the first synapse to the Superior Olive to Thalamus
* Neurons from the left and right Olive work together to calculate time differences
* This assists in sound localisation
38
Interaural Level Difference
* Frequency levels will be different in one ear over the other.
* The Medial Superior Olive receives info from both ears and uses the differences to assist in localisation
* There will be different levels of frequency depending on how much the frequencies are blocked by our heads
* This works well for high frequencies
* Low frequencies are better at working around the head anyway.
* Excitatory Neural synapses from here lead to the Lateral Superior Olive from the ipsilateral ear.
* Inhibitiry Neural synapses from here lead to the Lateral Superior Olive from the contralateral ear.
39
Lateral Superior Olive
* A relay station that Calculates the frequency differences and ILDs from both ears to assist localisation
* Excitatory synapses come from the ipsalateral ear
* Inhibitory synapses come from the contralateral ear
40
Cone of confusion
* There are positions in space around the azimuth where the ITDs & ILDs are the same.
* In this case the Olives will tell us the location of two positions front and back are the same.
* These positions are situated at the same place at 180o in front and behind us.
Marco Polo Game as an example; these are the best places to stand and not get caught.
* Elevation adds another dimension to help distinguish this problem
* Turning our heads to disambiguate can help too.
41
Directional Transfer Function (DTF)
* How the shape of our pinnae, ear canal, head and torso can affect the intensity of sounds and frequencies arriving at each ear
* each person has a unique DTF to determine localisation based on the azimuth and elevation of that sound
42
Ventriloquism Effect
* Sound localisation can be influenced by visual stimulus.
* If the audio-visual stimulus is strong enough we can localise a sound as if it is coming from the visual space
eg: a ventriloquist dummy. The illusion still works even when we know it is happening,
43
Auditory Distance Perception
* The simplest cue is **relative intensity** of sound
* Sounds that are closer to us are louder than sounds that are far away.
* Works best when we are familiar with a sound and we know how loud or soft it should be
44
Relative Intensity of Sound
* Sounds that are closer to us are louder than sounds that are far away.
45
Inverse Square Law
* Relativity of Sound only works at distances of about 1 metre
* Decrease in intensity of a sound is equal to the Distance2 from the sound
* As an object moves away from us, its sound decreases faster.
* For this reason we can over and understimate the intensity of sounds as they move.
46
Auditory Scene Analysis
* The method to sort out multiple sources of sound in an environment
* Uses information from:
* visual stimulus
* Interaural Time Differences
* Interaural Level Differences
* Pitch
* Timbre
* Onset Time
47
Onset Time
* If two sounds start at different times it is likely they come from different sources
*
48
Continuity and Restoration Effect
* We can have auditory restoration and phonemic restoration
*
49
Restoration Effect
* Masking sounds and brain fills in gaps in sound so that it sounds continuous
* There has to be a masking sound other=wise the brain will not fill in the continuous sound
50
Articulation
* Converting the sounds made by the vocal tract into phonemes and speech
51
Formant
* Different parts of our articulation repeat at different frequencies
* This creates formants in the speech spectrum
52
Formants are listed by Number
* F1 tells about the height of the tongue in the mouth
* F2 tells about how forward or back the tongue is
* F3 is a combination of the above
* We can distinguish most sounds in the English language based on these three formants
53
Phonemes
* The sounds that make up words
* Almost like the letters but combinations such as th and ph are also phonemes
* The smallest unit of sound that has meaning
54
Classifying Speech sounds – Place of articulation
Based on the location in which the sound is made such as b, p, m are all lip sounds
55
Classifying Speech sounds – Manner of articulation
Depends on the manner and amount of air being obstructed to construct that sound
56
Categorical Perception
* Situation in which a speech stimulus is perceived in terms of its category membership
* Not in terms of its surface properties.
* We perceive an utterance as a specific syllable, word, or phrase.
57
Motor Theory of Speech Perception
* McGurk Effect – Vision plays a huge role in how we perceive sound,
58
Aphasia
* Inability to have language
* Wernicke
* Broca – speech production problems, stilted speech, simple sentence but have good comprehension and speech perception
* Wernicke – nonsensical sentences, clear words but without meaning, little comprehension and understanding of speech perception
59
Babies and Music
* Processing music is innate and babies who are very young can differenitate preffered tunes
* Babies prefer their mother's singing to other female voices
* consistently prefer consonant to dissonant melodies from as young as 4 months
