S&H: lecture III-Exam 1
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11 terms
Terms | Definitions |
|---|---|
 3 CHARACTERISTICS OF SOUND (how we perceive them) | FREQUENCY (pitch) INTENSITY (loudness) PERIODICITY/SPECTRUM (quality) |
| 1) What is FREQUENCY? 2) FREQUENCY and its relationship to PITCH: | 1) The number of complete cycles of vibration occurring in a second. 2) Not linear; At higher frequencies, it takes more frequency change to get an equivalent pitch change. --From middle C to C sharp; less frequency change than from High C to C sharp. |
| FREQUENCY / PITCH expanded: | Rougher sounds are perceived as lower pitch than clearer sounds: its frequency Lowest to highest frequency the human ear can detect: 20 to 20K Hz. Usable range (what we use day to day): 100 Hz - 5K Hz. Speech: 80 Hz - 500 Hz; Noises for consonants: 80 - 500 Hz |
| We measure Frequency with Hz, and we measure Pitch with: | PERIOD; a 100 hz tone is 1/100th sec (low pitch) --Most pitch perception: periodic complexes, or pure tones --You can have perception of pitch for nonperiodic complex tones; |
| 1) What is INTENSITY? 2)INTENSITY (loudness) is directly related to: | 1) Magnitude of sound expressed in power or pressure; --The underlying physical (acoustic) characteristic of a sound that leads to our perception of a sounds' loudness. 2) amplitude (distance away from point of rest) |
| How do we measure Intensity? | In POWER: Watt/cm squared (a watt is a flow of electricity) In PRESSURE (force over surface area)--how we measure Intensity in speech: dynes/ cm squared. |
| The dB scale: | --A logarithmic ratio scale comparing one sound to another; the scale converts a large range of sounds the ear is sensitive to into manageable numbers; smaller value scale, in which each dB is equivalent into a just noticeable difference. |
| The dB scale formula, and what it means: | dB SPL = 20 log 10 P1/P2 --Logarithm is how many times a number must be multiplied by itself to give you another number; in this case, log to the base 10. For ex: 20 log 10 100/1 = 20 * 2 = 40 Answer = 40 dB SLP --So when you've got a sound whose pressure is 100 time greater than another sound, the solution = 2, b/c 10 squared = 100. So 20 * 2 = 40 db SPL. Another ex: : 20 log 10 1000/1 = 20 * 3 = 60. Answer = 60 db SPL. |
| 1) SPECTRUM (quality) a) what is the lowest spectrum of sound? | 1) what frequencies comprise any sound; how we distinguish between sounds (for ex, flute & piano have different spectrum.) a) a single frequency |
| b) PERIODICITY (paired with Spectrum) | 2) whether or not the pattern or oscillation of the sound-wave repeats, or how it is repeating --pure tones are only tones whose periodicity is same cycle to cycle |
| Oscillation | --synonymous with vibration --when my voice oscillates, the medium (air molecules) around me oscillates. |
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