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Perception > Problem 7 > Flashcards

Problem 7 Flashcards

1
Q

Physical definition of sound

A

Sound is pressure changes in the air

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2
Q

Perceptual definition of sound

A

Sound is the experience we have when we hear

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3
Q

Condensation

A

Causes an increase in the density of air molecules

–> increased air pressure

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4
Q

Rarefaction

A

Decreased density of air molecules

–> decreased air pressure

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5
Q

Pure tone

A

Occurs when changes in air pressure occur in a sine wave

  • -> fundamental building blocks of sound
  • -> rare in the environment
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6
Q

Frequency

A

The number of cycles per second that the pressure changes repeat

–> measured in hertz (Hz)

ex.: 1 Hz = 1 cycle/s

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7
Q

Amplitude

A

The size of the pressure change

–> difference in pressure between high + low peaks of the sound wave

(dB)

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8
Q

Complex tones

A

Consist of a number of pure tunes components added together

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9
Q

Harmonics

A

Refer to the components of complex tones

–> integer multiples of the fundamental

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10
Q

Fundamental/

First harmonic

A

The lowest frequency that is physically present in the sound

–> lowest tone of the harmonic series (longest WL)

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11
Q

Loudness

A

The perceptual quality, most closely related to amplitude, of an auditory stimulus

  • -> expressed in decibels
  • -> depends on amplitude + frequency
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12
Q

Audibility curve

A

Indicates the threshold for hearing vs frequency

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13
Q

Auditory response area

A

Area above the audibility curve

–> indicates where we can here sounds

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14
Q

Equal loudness curve

A

Indicates the sound levels that create the same perception of loudness at different frequencies

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15
Q

Pitch

A

The perceptual quality we describe as “high” or “low”

  • -> associated with music, speech + other natural sounds
  • -> can’t be measured in a physical way, but measured by how we perceive it

=> our sense of pitch is limited to those frequencies that create phase locking

(<5.000 Hz)

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16
Q

Tone height

A

The perceptual experience of increasing pitch that accompanies increases in a tones fundamental frequency

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17
Q

Tone chroma

A

Notes with the same letter

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18
Q

Effect of the missing fundamental

A

Describes the constancy of pitch even when the fundamental or other harmonies are removed

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19
Q

Timbre

A

Describes the quality between 2 tones that have the same

a) loudness
b) pitch
c) duration

but still sound different

ex.: flute + oboes may play the same note but sound different

20
Q

What influences the differences described in Timbre ?

A

a) attack

b) decay

21
Q

Attack

A

The buildup of sound at the beginning of the tone

–> “fade-in” time

22
Q

Decay

A

Decrease in sound at the end of the tone

–> “fade-out” time

23
Q

Pinnae

A

Structures that stick out from the sides of the head

24
Q

Outer ear

A

Consists of

a) pinnae
b) auditory canal

25
Q

Auditory canal

A

Tubelike structure

  • -> protects the structures of the middle ear
  • -> enhances the intensities of some sounds
26
Q

Middle ear

A

Small cavity that separates the outer + inner ears

–> contains the ossicles

27
Q

Ossicles

A

3 smallest bones in the body, that make up the middle ear

a) malleus
b) incus
c) stapes

28
Q

Tympanic membrane/

Eardrum

A

Located between the outer + middle ear

29
Q

Middle Ear muscles

A

Smallest skelletal muscles that are attached to the ossicles

–> at very high sound levels they contract to dampen the ossicles vibration

ex.: contract so that sounds from chewing won’t interfere with the perception of speech from other people

30
Q

Cochlea

A

Snail like structure

  • -> main structure of the inner ear
  • -> performs fourier analysis (Tonotopy)
31
Q

Scala vestibuli

A

Upper half of the cochlea

32
Q

Scala tympani

A

Lower half of the cochlea

33
Q

Cochlear partition

A

Separates the 2 scalas

34
Q

Organ of corti

A

Located between the 2 scalas of the cochlea

–> contains

a) basilar membrane
b) tectorial membrane
c) hair cells –> receptors for hearing

35
Q

Cilia

A

Thin processes extending from the tops of the hair cells

–> bend in response to pressure changes

36
Q

Phase locking

A

The property of firing at the same place in the sound stimulus

  • -> refractory period
  • -> only occurs at frequencies below 5.000 Hz
37
Q

Temporal coding

A

Groups of neurons of the auditory system respond to a sound by firing action potentials slightly out of phase with one another so that when combined, a greater frequency of sound can be encoded and sent to the brain to be analyzed

38
Q

Place theory of hearing

A

The frequency of a sound is indicated by the place along the cochlea at which nerve firing is highest

–> each place on the basil membrane is tuned to respond best to a different frequency

39
Q

Cochlear implant

A

Used to create hearing in people with deafness caused by damage to the hair cells in the chochlea

–> consists of

a) microphone
b) sound processor

c) transmitter
- -> sends signals to the electrodes implanted along the cochlea

40
Q

Cochlear amplifier

A

Outer hair cells expand + contract in response to the vibration of the basilar membrane

–> this action amplifies/sharpens vibration on the basilar membrane

–> basilar membrane vibrates to each harmonic

41
Q

How are pressure changes changed into electricity ?

A
  1. Sound waves reach the tympanic membrane + set it into vibration
  2. Consequently the following structures are set into vibration

a) Malleus
b) Incus
c) Stapes

  1. Stapes transmits the virbrations to inner ear by pushing on the membrane covering the oval window
  2. This movement of the stapes, sets cochlea into vibration
  3. Back + forth motion of oval window transmits the vibrations to the liquid inside of the cochlea
  4. Basil membrane is set into motion
  5. Organ of corti is set into an up + down motion
    - -> tectorial membrane is moved back and forth
  6. Cilia bend, because they are in contact with tectorial m.
  7. Cilias movement to the right causes the tip links to stretch which opens ion channels
  8. Na+ ions flow into cell
  9. Bending in other direction closes channels
    - -> back + forth bending causes alternating bursts od electrical signals
42
Q

Which density problem occurs in the ear ?

A

Inner ear contains a watery liquid

  • -> water is more dense
  • -> vibrations that would be directly passed from the air into liquid wouldn’t reach its destination
43
Q

How do the ossicles resolve the density problem ?

A

a) by being hinged
- -> lever action

b) by concentrating the vibration on stapes which increases the pressure

44
Q

Hearing range

A

–> one can hear sounds between 20 Hz - 20.000 Hz

–> one is most sensitive to sounds betw. 2.000 - 4.500 Hz (Speaking range)

45
Q

Fourier analysis

A

The analysis of a periodic function into its simple sinusoidal or harmonic components

46
Q

Auditory masking

A

Refers to one sound covering or masking another - making it virtually impossible to hear the sound being masked

–> effect is strongest for high frequencies

Perception (9 decks)

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