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23 Cards in this Set
- Front
- Back
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Interference Patterns
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Air molecules vibrate in place, they can be responsive to many signals at one time.
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If the two signals of the same frequency are “in phase” ....
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Their pressure waves crest and trough at the same time.
Sum of the amplitudes of each wave. |
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If they are 90 degrees out of phase (one signal is ¼ cycle ahead of the other)..
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The amplitudes of each are simply added.
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If they are 180 degrees out of phase..
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The result is silence. Each particle has been subjected to equal forces acting in opposing directions.
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Pure tone
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A single periodic frequency-vibrating in Simple Harmonic Motion/ creates a sine wave
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Complex tones
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Many sine waves of different frequencies.
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Complex Periodic Sound Wave
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If the pattern of vibration, no matter how complex, repeats itself
(note on the piano, sing “ah”). |
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Complex Aperiodic Sound Wave
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If the vibration is random and has no repeatable pattern.
(Hiss through your teeth, drop a book). |
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The fundamental frequency
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Is based on the rate at which the sound source produces its vibratory cycle.
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Harmonic series
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Each of the tones created by such a complex vibration is called a “harmonic.” The whole set of tones
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Fourier Analysis or Spectral Analysis
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Indicates the frequency and amplitude of each harmonic in a complex periodic wave.
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Pure tone
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A simple periodic tone has one component frequency
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Complex tone
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A complex periodic tone has 2 or more component frequencies that are related harmonically
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Amplitude
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The extent of particle displacement, is an indication of the intensity or power of the sound.Measured in decibel (dB)
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Loudness
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Signal is directly related to its intensity, so as intensity increases, the sound is judged by listeners
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Frequency
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Number of vibratory cycles/sec= Hz
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100 to 5000 Hz. Range
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The important frequencies for comprehending the speech signal are within
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Pitch
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A sensation. It is the perception that is experienced by the listener when frequency changes
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Period
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The time it takes for one cycle to be completed. This is measured in milliseconds (ms).
P = 1/F |
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Velocity
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Speed in a certain direction.
When in normal atmospheric conditions, sound travels through air |
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Wavelength
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The length of a sound wave is the distance in space that one cycle occupies.
Equation: λ = c / f |
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Wavelength depends on two factors
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The frequency of the vibration and the velocity of the sound wave.
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The 3 Velocity formulas
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344 meters per second
1130 feet per second 758 miles per second |
