07:700:135 Lecture 4: 13912-MusDigAud-2016-09-22
Document Summary
Changes in air pressure wave: compression (high pressure) and rarefaction (low pressure) Anatomy of a waveform: y axis = amplitude, x axis = time, as amplitude increases, so does pressure, characteristics. Frequency (observed: measured in cycles per second (hertz) hz, pitch: perception, limits of humans hearing: 20 hz - 20 khz, a4: 440 hz. A5: 880 hz: sine wave shows amplitude over time. Amplitude: distance above or below centerline of waveform, contributes to perceived volume. Wavelength: distance between beginning and end of a cycle, period: time it takes to complete on cycle. Phase: used to specify a particular point in time of a wave form, use to compare the relative positions of two waveforms, we care if waves are in phase and out of phase. Named after physicist christian doppler explained in 1842. Stationary person perceives pitch change of ambulance as it passes: representing sound. Time domain display, or waveform display (audacity) Use les presented, or record something yourself.
