Perception Final
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117 terms
Terms | Definitions |
|---|---|
 Physical def of sound | pressure changes in the air or other medium |
| Perceptual definition of sound | the experience we have when we hear |
| condensation | when diaphragm of speaker moves out pushing air molecules together |
| rarefaction | when diaphragm of speaker moves in pushing air molecules apart |
| pressure regions | condensation / rarefaction cycle creates high and low pressure regions that travel through air |
| pure tone | created by sine wave |
| amplitude | size of pressure change |
| What is the perception of amplitude? | loudness |
| frequency | number of times per second that pressure changes repeat |
| what is the perception of frequency? | pitch |
| how is amplitude measured? | decibel (dB) |
| how is frequency measured? | hertz (Hz); 1 Hz is 1 cycle/sec |
| fundamental frequency | the repetition rate |
| the first harmonic | repetition rate |
| harmonics | pure tones that make up periodic complex tones |
| additive synthesis | process of adding harmonics to create complex sounds |
| frequency spectrum | display of harmonics of a complex sound |
| pitch | the quality of sound, ranging from low to high; closely associated with frequency of a tone |
| tone height | increasing pitch that accompanies increases in a tone's fundamental frequency |
| how are the same notes on musical scales related? | have same fundamental frequencies that are multiples of each other |
| tone chroma | perception as similar tones; ie. music notes on different octaves |
| periodicity pitch | constancy of pitch, even when the fundamental or other harmonics are removed |
| what happens when fundamental frequency is removed? | it does not change the tone's pitch |
| human hearing range | 20 - 20,000 Hz |
| Audibility curve | shows threshold of hearing in relation to frequency |
| Humans are most sensitive to what frequency range? | 2,000 - 4,000 Hz |
| How are equal loudness curves determined? | -using a standard 1,000 Hz tone -two dB levels used - 40 and 80 -participants matched perceived loudness of all other tones to the standard -dB as a function of frequency |
| how are different tones of different loudnesses perceived at 80 dB? | almost all perceived as equal loudness |
| how are different tones of different loudnesses perceived at 40 dB? | Softer for high and low frequencies than the rest of the tones in the range |
| Timbre | quality that distinguishes between two tones that have the same loudness, pitch and duration but still sound different |
| Timbre depends on | tone's attack- buildup of sound at the beginning of the tone tone's decay- the decrease in sound at the end of a tone |
| Outer ear | pinna and auditory canal |
| function of pinna | sound location |
| what is auditory canal? | tube-like 3cm long structure |
| auditory canal amplifies frequencies at what level range? | 1,000 - 5,000 Hz |
| Function of auditory canal | protects tympanic membrane (eardrum) at the end of the canal |
| What is the middle ear? | two cubic centimeter cavity separating inner from outer ear |
| middle ear is made up of what? | 3 ossicles: malleus, incus, stapes |
| function of malleus | aka hammer- moves due to vibration of eardrum |
| function of incus | aka anvil- transmits vibrations of malleus |
| function of stapes | aka stirrup- transmits vibrations of incus to the inner ear via the oval window of the cochlea |
| function of ossicles overall | outer and middle ear are filled with air, inner ear is filled with fluid, pressure changes in air transmit poorly into the denser fluid; ossicles act to amplify the vibration for better transmission to the fluid |
| how do middle ear muscles aid in ossicles's function? | dampen their vibrations to protect the inner ear from potentially damaging stimuli |
| main structure of middle ear | cochlea |
| what is cochlea? | fluid-filled snail-like structure (35mm long) set into vibration by stapes |
| What is organ of corti? | structure in the cochlea that contain inner and outer hair cell receptors for hearing |
| transduction takes place by: | -cilia bend in response to movement of organ of corti and the tectorial membrane -movement in one direction opens ion channels -movement in other directions closes channels |
| Bekesys's Place Theory | Frequency of sound is indicated by the place on the organ of corti that has the highest firing rate -observation in cadavers and model shows the vibrating motion of the membrane is a traveling wave |
| apex responds best to what frequencies? | low |
| base responds best to what frequencies? | high |
| Tonotopic map | cochlea shoes an orderly map of frequencies along its length |
| How does basilar membrane respond to complex tones? | There are peaks in the membrane's vibration that correspond to each harmonic in a complex tone |
| conductive hearing loss | blockage of sound from receptor cells |
| sensorineural hearing loss | damage to hair cells, auditory nerve, or brain |
| prebycusis | most common type of sensorineural hearing loss -greatest loss is high frequencies -males more severely than females -appears to be caused by exposure to damaging noises or drugs |
| pathway from cochlea to cortex | -cochlear nucleus -superior olivary nucleus (in brain stem) -inferior colliculus (in midbrain) -medial geniculate nucleus (in thalamus) -auditory receiving area (A1 in temporal lobe) |
| Pathway of hearing in cortex | -from core, then belt, then parabelt -simple sounds activate core -complex sounds activate belt and parabelt |
| cochlear implants | electrodes are inserted into the cochlea to electrically stimulate auditory nerve fibers |
| auditory space | surrounds an observer and exists wherever there is sound |
| azimuth coordinates | position left to right |
| elevation coordinates | position up and down |
| distance coordinates | position from observer |
| why must location for sounds be calculated? | because location cues are not contained in the receptor cells like on the retina in vision |
| Binaural cues | location cues based on the comparison of the signals received by the left and right ears |
| Interaural time difference | difference between the times sounds reach the two ears; when source is to the side of the observer, the times between each ear will differ |
| Interaural level difference | difference in sound pressure level reaching the two ears; Reduction in intensity occurs for high frequency sounds for the far ear; no effect for low frequency sounds |
| cone of confusion | where the interaural time difference and interaural level difference are the same |
| auditory scene analysis | process by which sound sources in the auditory scene are separated into individual perceptions; this does not happen at the cochlea since simultaneous sounds are together in the pattern of vibration of the basilar membrane |
| how onset time helps to perceptually organize stimuli | sounds that start at different times are likely to come from different sources |
| how location helps to perceptually organize stimuli | a single sound source tends to come from one location and to move continuously |
| how similarity of timbre and pitch helps to perceptually organize stimuli | similar sounds are grouped together |
| how proximity in time helps to perceptually organize stimuli | sounds that occur in rapid succession usually come from the same source |
| how auditor continuity helps to perceptually organize stimuli | sounds that stay constant or change smoothly are usually from the same source |
| direct sound | sound that reaches the listener's ears straight from the source |
| indirect sound | sound that is reflected off of environmental surfaces and then to the listener |
| Factors that affect perception in concert halls | -reverberation time - best is 2 sec -intimacy time - best is 20 ms -bass ratio - high are best -spaciousness factor - high are best |
| reverberation time | time it takes sound to decrease by 1/1000th of its original pressure |
| intimacy time | time between when sound leaves its source and when the first reflection arrives |
| bass ratio | ratio of low to middle frequencies reflected from surfaces |
| spaciousness factor | fraction of all the sound received by listener that is indirect |
| Ideal reverberation time for classrooms | .4 to .6 seconds |
| Visual capture or the ventriloquist effect | an observer perceives the sound as coming from the visual location rather than the source for the sound |
| shape of vocal tract is altered by what? | moving articulators |
| how are vowels produced? | by vibration of the vocal cords and changes in the shape of the vocal tract by moving the articulators |
| how are consonants produced? | by a constriction of the vocal tract |
| formant | specific frequencies where peaks of pressure occur due to change in shape of the moving articulators |
| first formant's frequency | first is lowest, and gets higher as numbers go up |
| Sound spectrograms | show the changes in frequency and intensity for speech |
| Formant transitions | rapid changes in frequency preceding or following consonants |
| Phoneme | smallest unit of speech that changes meaning of a word; 47 in english |
| The variability problem | there is no simple correspondence between the acoustic signal and individual phonemes; Variability comes from a phoneme's context |
| coarticulation | overlap between articulation of neighboring phonemes also causes variation |
| Categorical Perception | Occurs when a wide range of acoustic cues results in the perception of a limited number of sound categories |
| Voice Onset Time | Time delay between when a sound starts and when vocal cords begins vibrating |
| Phonemic Restoration Effect | Used to show that speech perception is determined both by the nature of the acoustic signal and by context that produces expectations in the listener |
| The segmentation problem | there are no physical breaks in the continuous acoustic signal, but breaks between words are still perceived |
| Transitional probabilities | the chance that one sound will follow another in a language |
| Statistical learning | the process of learning transitional probabilities and other language characteristics; infants as young as 8 months show this |
| Indexical characteristics | characteristics of the speaker's voice such as age, gender, emotional state, level of seriousness, etc. |
| Is speech perception a top-down or bottom-up process? | It's both. Knowledge/meaning + acoustic signal leads to speech perception |
| Broca's aphasia | damage in frontal lobe Labored and stilted speech, can only speak in short sentences Capable of comprehending what others are saying |
| Wernicke's aphasia | damage in Wernicke's area in temporal lobe Speak fluently but the content is disorganized and not meaningful They also have difficulty understanding others and word deafness may occur in extreme cases. |
| where is voice area in brain? | superior temporal sulcus |
| dual stream model of speech perception | ventral stream for recognizing speech and a dorsal stream that links the acoustic signal to movements for producing speech |
| how does damage to parietal lobe impact speech perception? | difficulty discriminating between syllables but can still understand words |
| Experience Dependent Speech Plasticity | The brain becomes "tuned" to respond best to speech sounds that are in the environment |
| somatosensory system | cutaneous senses, proprioception, kinesthesis |
| Cutaneous senses | perception of touch and pain from stimulation of the skin |
| proprioception | ability to sense position of the body and limbs |
| kinesthesis | ability to sense movement of body and limbs |
| where are mechanoreceptors located? | in the dermis of the skin |
| Merkel receptor | fires continuously while stimulus is present; Responsible for sensing fine details |
| Meissner corpuscle | fires only when a stimulus is first applied and when it is removed; Responsible for controlling hand-grip |
| Ruffini cylinder | fires continuously to stimulation; Associated with perceiving stretching of the skin |
| Pacinian corpuscle | fires only when a stimulus is first applied and when it is removed; Associated with sensing rapid vibrations and fine texture |
| Medial lemniscal pathway consists of | large fibers that carry proprioceptive and touch information |
| Spinothalamic pathway consists of | smaller fibers that carry temperature and pain information |
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