# Signals & Analysis - week 1+2

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• Signals & Analysis
• A decibel is the just noticeable difference in signal levels
• A decibel is 1/10 of a bell
• dB = 10 x log(p1/p2)
• dB = 10 x log(vp1^2/vp2^2)
• dB = 20 x log(vRMS1/RMSvP2) = SNR
• dB = 20 x log(vp1/vp2) = dynamic range
• Phase delay
• phase = tdelay/tcycle * 360 degrees
• tdelay = the delay time of two waves at the same point in amplitude (usually measured at the zero crossing point)
• Destructive wave interference is where waves that are out of phase combine to give a negative, cancelled effect
• Constructive wave interference is where waves that are in phase combine to give a positive, boosted effect
• Phase delay can only be calculated if both waves are the same frequency
• phase = tdelay/tcycle * 2PI radians
• tcycle = 1 full oscillation of wave A
• Analogue or digital
• Physical/Psychophysical representations of sound
• Human hearing range is 20Hz - 20kHz
• Wave properties
• RMS is Root Mean Square Amplitude
• RMS = peak value / root(2)
• RMS = peak-peak x 0.354 or peak x 0.707
• 1 period or cycle is from peak to peak
• Peak is from 0 to the max amplitude
• Peak-peak is from min amplitude to max