PHYS-P 105 : FINAL EXAM
79 Cards in this Set
Front | Back |
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sound
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auditory sensation in the ear
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What is the study of sound?
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acoustics
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sound wave
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carries information or energy from one point to another
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sound wave
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carries information or energy from one point to another
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Two types of waves
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longitudinal and transverse
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longitudinal wave
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compressional wave, sound in air
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transverse
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direction of wave is perpendicular to the propagation of the wave
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Frequency (audible) range of a sound wave
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20 Hz to 20 KHz
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What happens to polarity if a wave pulse on a string is reflected from a fixed end? a free end?
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polarity is inverted; reflects the wave
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progressive/ traveling wave
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consists of a disturbance moving from source to surrounding place, transferring energy
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Standing Wave
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A wave pattern that results when two waves of the same frequency, wavelength, and amplitude travel in opposite directions and interfere
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superposition of a wave
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constructive/destructive, add or subtract amplitudes
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Wave Interference
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Two waves collide to create large or smaller wave
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wave propagation
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the way a wave travels
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Wave lengths and doppler effect:
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Longer wavelength: when the sound moves away from you- lower pitch
Shorter wave length- when sound moves towards you- higher pitch
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wave reflection
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wave hits barrier and reflects back with little energy loss
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wave refraction
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wave hits barrier and reflects back with energy loss
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diffraction
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low frequency waves diffract more than high frequency waves
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resonance
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the response of standing waves to others of the same frequency
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partial harmonics
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waves in sound that
are integer multiples of the fundamental frequency
are of decreasing energy as distance grows from the fundamental frequency
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Overtones/partial
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all of the tones over the fundamental frequency.
Partials: Includes fundamental frequencies, but overtones do not.
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acoustic impedance
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Opposition of flow of energy
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Sound pressure
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changes in air pressure due to the passage of sound energy
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Outer Ear
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- pinna
- external auditory canal
Ear Drum
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middle ear
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-Oval window
-eustachian tube
-auditory ossicles
Regulates ear pressure
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Inner ear
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-cochlea
functions in hearing and balance; filled with fluid
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place pitch theory of pitch perception:
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freq=distance traveled on basilar membrane
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critical bands
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frequency regions in cochlea need to recognize a separation in the brain btw frequencies
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a critical band for a given frequency is:
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-100 Hz below 500 Hz
-10%-20% of the frequency above 500 Hz
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Masking Sound
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when to separate sources of sound are perceived simultaneously, obscuring each other
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psychophysics
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the measure of stimulus strength and sensitivity to the stimulus
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Fourier analysis breaks up complex tones into 2 things:
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fundamental frequency
&
harmonics
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fourier synthesis
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adds amplitudes of waveforms
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pure tones with slightly different frequencies are:
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beats/rough tones
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when two pure tones are within 15 Hz of each other we hear:
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the difference in freq. btw the two and the average pitch
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when two pure tones are greater than 15 Hz but less than the limit of freq. discrimination:
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we hear a rough tone and the average freq.
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when two pure tones are greater than the limit of freq. discrimination:
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we hear them as individual tones
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combination tones
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when 2 loud tones are sounded together, a 3rd tone is heard thats not actually present in the audible sound
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Dissonance
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Uncomplimentary tones; disharmonious, builds tension
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consonance
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repetition of final consonant sounds
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all western scales use the:
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octave
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pythagorean scale
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based on intervals of fifths
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equal temperament
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12 pitches per octave
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What instruments are in the brass family?
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trumpet, cornet, trombone, tuba, French horn, etc.
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oscillations in a pipe
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variations of phase and amplitude
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which family has a mouthpiece and a bell?
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brass
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white noise
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all frequencies with each frequency having the same amplitude
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phoneme
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smallest unit of speech
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formants
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frequency regions of phonemes where harmonics have high amplitudes
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speech sounds can be analyzed using:
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spectrograms
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spectrogram
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graph of frequency (y-axis) as a function of time (x-axis)
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Direct current
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electrons flowing through a wire in a single direction
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volt
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unit of energy per unit charge
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basic unit of current
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Amp
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alternating current
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voltage that changes in a sinusoidal manner
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effective voltage
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the ac voltage that would have the same effect as a dc voltage
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dynamic loudspeaker
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has a cone and voice coil, current flows through coil which moves due to Faraday's law
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electrostatic speaker
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conductors on outside separated by an insulator, when voltage is applied it bends which moves air and creates sound
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shortcoming of a speaker
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sound from the back will interfere with sound from the front causing reduced response
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Three basic types of enclosures
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infinite baffle, acoustic suspension, tuned port/bass reflex system
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loudspeakers in general have limited ranges of:
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frequency response
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woofer
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a loudspeaker designed to produce a low-frequency sound
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Tweeter
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A loudspeaker designed to produce high frequency sounds
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how are electrical signals from the amplifier split up and how are they sent to the correct speaker?
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split up by frequency and sent to the correct speaker by a crossover circuit
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microphone
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converts sound pressure or sound velocity to a voltage
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what are the two ways in which microphones are classified?
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-type of transducer
-directionality
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electromagnetic microphone
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voltage generated by motion of conducting coil, voltage output is low and must be amplified
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piezoelectric microphone
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voltage generated by squeezing a crystal, has high output impedance
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Condenser Microphone
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high quality mic that can be very small and is generally powered by phantom power or a power supply
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bidirectional microphone
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most sensitive to the front and back
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unidirectional microphone
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most sensitive to front
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omnidirectional microphone
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equally sensitive in all directions, "perfect"
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analog to digital converter
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converts sound waves into digital signals
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digital to analog converter
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converts digital data into voltage/electric charge
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how many digits do binary numbers have? digital?
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2 (0 and 1); 10
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how many bits make a byte? a nibble?
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8; 4
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Lossy and lossless
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-Lossy: can't restore file to original state (usually media)
-Lossless: can restore file to original state (usually text files)
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what type of recording to compact disks use?
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16 bit recording
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Nyquist Criteria
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Minimum sampling rate (2*max frequency)
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