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36 Cards in this Set
- Front
- Back
What is the function of hearing?
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Hearing has signaling function, also music and speech
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What did Hellen Keller say about being deaf
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she was both blind and deaf, but she felt that being deaf is worse than being blind, because blindness isolated her from things but deafness isolated her from people
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How can sound be defined?
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Sound can be defined as physical stimulus or a perceptual response
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When the tree falls in the forest, will there be a sound if there is no one to listen?
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if the sound is defined as physical stimulus (pressure changes in the air or other medium) then yes, because falling tree causes pressure changes. Perceptual definition is that sound is experience we have when we hear, then the answer is no, because if no one is on the forest, there would be no experience
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Pure tone
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simple kind of sound, in which pressure changes occur in a pattern described by mathematical function called a sine wave
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Amplitude in speaker
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distance diaphragm moves out of its rest position
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Frequency in speaker
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number of times per second that speaker diaphragm goes through cycle of moving out, back in, and then out again
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Hertz
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one cycle per second
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What are frequencies humans can hear in?
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20-20.000 Hz
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Decibel
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unit of sound
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Equation to convert sound pressure to decibels
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# of Db = 20 log p/p0
p- sound pressure of stim. p0- standard sound pressure (20 micropascals) |
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SPL
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standard pressure level, when 20 micropascals used
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Multiplying sound pressure by 10 adds _ dB
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20
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Fourier analysis
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any complex waveform can be broken down into series of sine waves
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Fourier frequency spectrum
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plot that indicates each harmonics frequency by line position on the horizontal axis and its amplitude by the height of the line
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Audibility curve
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indicates how sensitivity changes across the frequencies that we can hear by plotting threshold for hearing vs frequency
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Auditory response area
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area above audibility curve, because we can hear tones that fall within that area
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Loudness
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magnitude of auditory sensation
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How to determine loudness given frequency and dB
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Loudness is judged relative to a standard of 1000 Hz at 40 dB, which is assigned a value of 1
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Pitch
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quality of tone that we describe as high or low
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How is pitch related to frequency
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Low frequencies cause low pitches, high frequencies cause high pitches
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Tone height
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property of increasing pitch that accompanies increases in tones frequency
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Tone chroma
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notes with the same letter have same tone chroma
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Timbre
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if two tones have same loudness, pitch and duration but sound different, then difference is timbre (flute and bassoon playing same note)
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Outer ear
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pinna + auditory canal
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Functions of outer ear
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protective function and enhancing intensities of sounds by means of resonance
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Resonance
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sound waves that are reflected back from the closed end of auditory canal interact with sound waves that are entering auditory canal
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Name 3 ossicles
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1. malleus - set in vibration by tympanic membrane, to which it is attached
2.incus- gets vibrations from malleus 3.stapes |
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How do ossicles amplify vibrations
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1) concentrating vibrations of large tympanic membrane on smaller stapes
2) create lever action |
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Middle ear muscles
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smallest skeletal muscles in body, attached to ossicles, at very high intensities contract to dampen ossicles vibration, protecting inner ear
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cochlea
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main structure of inner ear filled with liquid, liquid is set into vibration by movement of stapes against oval window
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organ of corti
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large structure in cochlear partition, contains receptors(hair cells), sits on top of basilar membrane, covered on top by basilar membrane
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2 types of hair cells
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inner hair cells and outer hair cells
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what do cilia in hair cells do?
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bending of cilia transduces vibrations caused by sound in electrical signals
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place theory of hearing
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frequency of sound is indicated by the place along the organ of Corti at which nerve firing is highest,so it states that frequency is indicated by which fibers are firing
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Apex of cochlea responds best to _ frequencies, base responds best to _ frequencies
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low, high
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