# sound and its measurements

 sound a compressional wave that can be described as1) psychologically aka an auditory experience2) physically- a series of disturbances of molecules Vibration the principle prerequisite for sound vibration is affected by the transmitting medium and sound source.the medium most have mass and elasticity elasticity the ability of an object to resist changes in shape or volume. The more densely packed molecules the more springier. Tuning fork Pitch Pitch is consistent when striking a tuning fork.  The only variables that change are the vibrations(amplitude) and the loudness. - mass and elasticity dictates how the fork osscilates Tuning fork motion At rest the tuning fork has kinetic energyat the centre and beyond resting the tuning fork has potential energy Pure tones the simplest of all sound waves sine waves allow us to represent a sound wave mathematically sine waves described in 3 ways 1)phase2)amplitude3)frequency Phase as a circle used to describe the starting position of the sound or the phase relationship between 2 or more sounds.  Can have the same amplitude and frequency but different phases We use phase for Localization constructive interference two sine waves add together destructive interference is when two sine waves cancel each other out resulting in no signal.  This happens when sine waves start at opposite phases amplitude measures of strength and magnitude of sound wave.  Measures in sound pressure. It relates to the force being applied to the source peak to peak maximum peak to maximum trough measurement root mean square amplitude the average of many points on a sine wave Frequency the rate at which a sine waves repeats itself over time. How much does it vibrate per second? f=1/T T=1/F Hearing ranges for normal hearing 20 hz to 20,000 but our best hearing is 1000-4000 Hz. Hearing tests show sensitivities from 250 Hz to 8000 Hz Speed of sound -influenced by the temperature and how dense the medium is. The tighter the molecules are packed the faster sound can travel.-not related to hertz wavelength and frequency inverse relationship. When wavelength increases freq decreases and when freq increases wavelength decreases-as speed of sound increases the wave length increases The longer the wavelength of a sound wave the thicker a walls needs to be to attenuate it.  When we test normal hearing at 20Hz we need to be in a room with thick walls. stationary source the frequency does not change so we hear the same pitch moving source as it approaches you the pitch gets higher then lower as it passes you (doppler affect) AuthorWesleypjones ID316350 Card Setsound and its measurements Descriptionsound and its measurements Updated2016-02-23T04:07:10Z Show Answers