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27 Cards in this Set
- Front
- Back
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Ultrasonic
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Sound frequency >20,000 Hz (we can't hear these, ie. dog whistle); doesn't travel in air but goes through liquids well
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Infrasonic
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Sound frequency less than 20 Hz
(generally below frequency of audible sound) fyi examples in nature volcanoes, earthquakes, avalanches, elephants (14 hz), rhinos. |
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Supersonic
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An object that moves faster than speed of sound (340 m/sec)
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Fundamental
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Lowest frequency
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Harmonic
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Integer multiple of fundamental; a wave's harmonic determines a note's tone quality
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Overtone
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a Higher frequency series; a generic term for some higher frequency than the fundamental
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Timbre
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tone quality; distinctive sound of a voice or instrument; frequency determined by the fundamental; tone quality determined by the wave shape
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Loudness
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proportional to the amplitude; INTENSITY
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Pitch
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proportional to the frequency; very slightly effected by loudness; what you hear
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Tone Quality
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Effected by the shape of the wave; what you hear; aka TIMBRE
I. tONE quality of a note is affected by the amplitude, frequency, number and timbre of its harmonics |
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Pressure
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Corresponds to the amplitude of the sound wave
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Intensity
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Corresponds to the power of the of the wave
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White Noise
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All frequencies present in equal amplitude, such that white light has all colors in it.
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Pink Noise
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Same energy in each octave; energy depends on the square of the amplitude; has larger component of low frequencies; is a calming, relaxing sound; used to mask unwanted sounds.
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Formant
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A specific frequency region wherein any harmonics are emphasized by the resonanat qualities of the instrument or vocal tract. Vocal resonance cabities; Larynx, mouth, nasal cavity.
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SPL
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Sound pressure level;
i. expressed in dB to indicate loudness. ii. 20 log(P/Po); Po= .0002 dynes/cm squared or 20 uPa |
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SIL
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Sound intensity level; Physical intensity of sound in air
i. 10log (I/Io);where Io = 1 E - 16W/cm squared at 1000 Hz |
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dB
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Decibel ; named after Alexander Graham Bell
i. decibel ii. 0 dB= 20 log(Po/Po) |
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Phon
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What people hear; comparison between power/heard power over a range of frequencies - all in reference to a 1000 Hz base (used with pure tones overall)
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dB HL
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Hearing Level is an individual's threshold of hearing (in dB) relative to a standard (typically the 0 phon level); Our hearing is impaired if HL is raised over 25 dB in the critical 500-2000 Hz region.
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Sones
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subjective judgment-what sounds "twice as loud"
i. Like the octave musical scale for frequency ii. Created to provide a linear scale for loudness iii. Taking the standard range for orchestral music is about 40 to 100 phons, if the lower end of that range is arbitrarily assigned a loudness of one sone, then 50 phons would have a loudness of 2 sones, 60 sones would be 40 sones, etc. iv. "How many times louder is this thing (than the 40 phon standard)." |
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Fourier analysis
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Identify harmonics from a screen display
a. Fourier Analysis refers to breaking down a complex wave into its harmonics b. Fourier's Theorem; Any Periodic wave shape can be constructed from an appropriate fundamental and its related harmonics. |
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How intensity varies with the distance from a source
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I=1/(d^2) example: If you move three times as far away from a loud sound source its intensity will be 1/9 as much as before. Example: You are sitting 5 feet away from a speak, you find the sound too loud so you move 20 feet away. How much less intense is the sound 20/5=4 4^2=16, so 16 times less intense than before.
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What determines the speed that a vibration (or a sound) travels?
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[The medium it's moving in; for a string, know the qualitative factors, I'll provide v in the string if needed].a. The speed of sound is variable and depends on the properties of the substance through which the wave is travelling. b. Velocity depends on the tension and the mass per unit length of the string.
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When are reflections inverted or not inverted?
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a. Fixed end: Inverts; walls pull down to hold end in place, generating a inverted reflection; stringed instruments
b. Free end: Reflects; No restraint, so end overshoots, generally a positive reflection; bull-whip or wind instrument. |
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How dB's change as identical sources are added or removed.
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a. 1 > 2 goes up +3 dB (ex: 60dB goes to 63 dB)
b. 1 > 3 goes up +5 dB(ex: 60 dBgoes to 65 dB) c. 1 > 4 goes up +6 dB(ex:60 dB goes to 66 dB) d. for something to be twice as loud, you have to add 10 dB which is ten times the original intensity |
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Know how to read a Fletcher-Munson graph
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dB to Phon, or Phon to dB at a specific frequency
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