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Unformatted text preview: Chapter 11 Pure tones: Diaphragm moves out air molecules condensed LOCAL density increases → → → pressure increases. Travels through the air at 340 m/s travels though water at 1500 m/s This travelling wave causes AIR PATICLES to move UP AND DOWN ! AIR PRESSURE changes move forward/inward → AIR PART ICLES move up and down but stay in the SAME place. Pure tones = one sine wave function Tuning forks designed to produce pure tones DB= 20x(change in pressure) p o =20 micropascals 20 micropascals is the minimum PRESSURE threshold for human hearing VIMP: M ULT IPLY ING pressure by 10 ADDS 20 Human frequency Range from 20HZ 20Khz → Complex tones: Periodic tone: means that the function repeats Pu re tones : frequency Complex tones : fundamental frequency To create the complex tone you need M U LT I P LES of the fundamental frequency i.e. harmonics. VIMP: removing the fundamental frequency changes only the WAVEFORM. Waveform =timber Amplitude Frequency Waveform Loudness/ pressure Pitch Timber Decibels Ha rmonic structure To determine the loudness of a sound you need both the DB and the frequency !!!!! Tone height Periodicity tone Periodicity pitch Tone chroma= double of fundamental frequency to give a similar perceptual experience. Depends on number strength harmonics attack/dec ay VIMP: INCREASING the sound level by 10 DB nearly DOUBLES the loudness. TONE HEIGHT= increasing of pitch by increasing the FUNDAMENTAL FREQUENCY = perceptual experience. Tone chroma: notes with the same letter sound similar. Tones with the same tone chroma have fundamental frequencies that are DOUBLED= similar perceptual experience. VIMP: the pitch is determined not by the FUNDAMENTAL FREQUENCY but by the spacing and the repetition rate. VIMP: note the difference: • PERIODICITY TONE : means has the property of repeating • PERIODICITY P I TCH : means the pitch we hear in which some harmonics are removed. Example males voice in a telephone....
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This note was uploaded on 04/20/2011 for the course PSYC 212 taught by Professor Shahin during the Fall '11 term at McGill.
- Fall '11