Voice Science Chapter 2: Nature of Sound
Terms
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- Frequency: doubling vs. raising by 50%
- 220Hz-440Hz = pitch raised by one octave; 220-330HZ = pitch raised by perfect fifth
- 1) harmonics; 2) partials
- 1) overtones that are whole number multiples of F0; 2) overtones that are not whole number multiples of F0.
- fundamental frequency
- lowest frequency in a complex sound wave; objective equivalent to musical pitch
- Sine wave graph: 1) apex, 2) nadir, 3) horizontal line
- 1) maximum compression pressure; 2) maximum rarefaction pressure; 3) point of equilibrium (0 pressure)
- 1) physical distance between cars; 2) number of cars; 3) time lapse between cars
- 1) wavelength, 2) frequency; 3) period
- amplitude (objective vs. subjective doubling)
- doubles acoustic pressure when adding 3dB (ex: 2 80dB sopranos = 83 dB); doubling in loudness = 3-10 dB
- 1) sound; 2) wave
- A series of compressions and rarefractions within a medium (for us, air); 2) transmission of sound
- frequency
- number of vibrations per second (Hz); time within sound (time delay between successive compression waves)
- wavelength
- The spatial separation between compressions or rarefactions (high frequency = short, straight waves- easily reflected; long wavelength = less directional)
- 4 components needed for musical sound
- Frequency, amplitude, spectral envelope, duration
- periodic sound
- A sound with pitch (periodicity distinguishes music from noise)
- spectral slope
- The rate at which HARMONICS decline in amplitude with increased frequency, expressed as a ratio through decibels per octave (sound in larynx before traveling through vocal tract) (exceeds 20dB for breathy voices- not enough to project; slope might be as low as 6 dB per octave for loud, dramatic voices- too harsh/strident)
- for a fundamental (F0) of 130 Hz, harmonics are present at ___, ___, ___
- 130 (F1), 260 (F2), 390 Hz
- period
- one cycle of vibration (compression and rarefaction)
- Process of sound reaching someone's ear:
- The sound source (folds) creates pressurization (compression) of air molecules followed immediately by depressurization (rarefaction). Individual molecule movement during compression starts chain reaction (each molecule bumps into its neighbor) and transfers compression wave along the line until it runs out of energy or impacts someone
- ear health
- amplitude rapidly dimishes as listener moves farther away; varies w/square of change in distance (4x way = amplitude decreases by 16; 2x as close = increase by 4). Normal hearing threshhold = 0-1dB; Sounds above 170 dB can be lethal.
- Order of harmonic series
- ddsdmstedrmfis (do-do-so-do-mi-so-te-do-re-mi-fi-so)
- amplitude
- The magnitude of compression/rarefaction (objective loudness)- dB
- overtone
- Additional frequency above the fundamental that is present in a complex tone.
- spectral envelope
- The relationship between F0 and overtones (objective timbre- subjective timbre can also be affected by aperiodic/inharmonic sounds like sliding guitar string and sighs)