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CSD313L_SoundIntensityPressureNarration

# We will use db il 10 log10ix ir to figure out to ix

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Unformatted text preview: og10(Ix / Ir) to figure out to Ix. dB IL / 10 = log10(Ix / Ir) 10 dB IL/10 = Ix / Ir 10 Ix = Ir * 10 dB IL/10 – Example, for a sound at 70 dB IL, how much is Example, Ix ? Ix = Ir * 10 dB IL/10 = 10 -12 * 10 70/10 = 10 -12 * 10 7 10 +7= -5 10 -5 watts/m2 = 10 -12 Sound Pressure Sound Another way to measure sound level Force applied on a unit area – p = F/A – 1 Pa = 1 N/m2 Range of acoustic pressure for humans: 2 x Range 10-5 Pa (the softest sound that is audible) to 10 20 Pa (the sound level starting to cause 20 discomfort) Acoustic Intensity and Pressure I = p2 / Z – Acoustic intensity (I) is equal to pressure (p) square divided by acoustic impedance (Z) – Acoustic impedance is the total opposition to sound energy transfer. Absolute and Relative Measure of Sound Pressure Sound Absolute measure of sound pressure – 2 x 10-5 Pa – 3 Pa Relative measure of sound pressure – px / pr (ratio), in which px is the target sound pressure and pr is reference sound pressure and – Reference sound pressure: pr = 2 x 10-5 Pa – For a sound with a pressure at 10-3 Pa Relative (ratio) measure: px / pr = 10-3 Pa / 2x10-5 Pa = 50, meaning this sound has a pressure 50 times higher than the reference sound. reference deciBe...
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