PHYSICS 109: exam 3
23 Cards in this Set
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open pipe
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air pressure can't build up, pressure node at open end
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closed pipe
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stopper keeps air from moving, node at closed end, antinode at open end, only odd partials
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The Fourier Theorum
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-any periodic oscillation of period T can be represented as a sum of sine waves with appropriate frequencies, phases, and amplitudes
-only certain frequencies are necessary - multiples of fundamental
-there is only on combination of sinusoidal oscillations that produces the given comple…
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sound spectrum
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graph that represents the amplitude of the various partials of a complex tone vs. the frequency of the partial
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pure tone
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tuning fork, one line on graph
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the missing fundamental
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amplitude is 0, no fundamental present, pitch still sounds like fundamental pitch, the brain reinstates it
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formants
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regions of the sound spectrum, stronger groups, result of broad resonances in the throat and oral cavity
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end correction
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-at open end, air is moving out and in and airflow tends to continue beyond end of tube
-makes tube act slightly longer
-end correction l added to L for each open end
-l=.3d
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musical scale
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sequence of frequencies, most often arranged in ascending order, normally contained within an octave
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musical intervals
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characterized by the ratio of the 2 frequencies, intervals sound the same if they have the same ratio
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polyphonic
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compositions in which 2 or more sounds are played simultaneously
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roughness
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when 2 frequencies are near one another but not so close that one discerns the beats individually
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triad
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a set of 3 tones often played as a chord
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just major scale
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sequence of frequencies relative to the first tone of frequency 1
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diatonic scales
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scales using 2 kinds of intervals, using whole and half steps
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augmented fourth
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from F to B, has 3 whole tones/6 semitones instead of 5 semitones
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minor sixth
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from E to C, has 8 semitones instead of 9
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chromatic scale
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scale that assigns definite frequencies to all 12 semitones
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natural scale
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scale that is played on a "natural horn" without values or tone holes playing only multiples of the fundamental frequency
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resonator
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at the center of the instrument, oscillating system
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excitation device
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sets the oscillator/resonator into motion
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radiator
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required for energy supplied by energy source to oscillator given off as sound wave
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feedback between oscillator and excitation
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excitation (buzzing lips) is driving force on resonator, resonator in turn affects the driving force (lips) to keep it at its resonant frequency
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PHYSICS 109: exam 3