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Unformatted text preview: ¡ Previous Lecture: ¡ Working with sound files ¡ Today’s Lecture: ¡ Frequency computation ¡ Touchtone phone ¡ Announcement: ¡ Section in the computer lab this week ¡ Project 6 due Monday Nov 23 ¡ Final exam Dec 14 (Mon) 7pm. Check for conflicts and email us ( [email protected] ) now. Specify your entire exam schedule including course numbers. We looked at the time domain last lecture 1 2 3 4 5 6 x 10 410.80.60.40.2 0.2 0.4 0.6 0.8 1 Austin Powers Sample number Time Nov 17, 2009 Lecture 23 3 What about the frequency domain? >> phone 0.01 0.02 0.03 0.04 0.0510.5 0.5 1 Time (sec) Signal Time Response 500 1000 1500 2000 1010 105 10 10 5 Frequency (Hz) Signal Power Spectrum Nov 17, 2009 Lecture 23 4 A “puretone” sound is a sinusoidal function ( ) t t y ω π 2 sin ) ( = ω = the frequency Higher frequency means that y(t) changes more rapidly with time. Nov 17, 2009 Lecture 23 5 0.2 0.4 0.6 0.8 110.80.60.40.2 0.2 0.4 0.6 0.8 1 omega = 4 ( ) t t y 4 2 sin ) ( ⋅ = π 0.2 0.4 0.6 0.8 110.80.60.40.2 0.2 0.4 0.6 0.8 1 omega = 8 ( ) t t y 8 2 sin ) ( ⋅ = π Still looking at the time domain Nov 17, 2009 Lecture 23 6 Digitize for Graphics % Sample “Rate” n = 200 % Sample times tFinal = 1; t = 0:(1/n):tFinal % Digitized Plot… omega = 8; y= sin(2*pi*omega*t) plot(t,y) Digitize for Sound % Sample Rate Fs = 32768 % Sample times tFinal = 1; t = 0:(1/Fs):tFinal % Digitized sound… omega = 800; y= sin(2*pi*omega*t); sound(y,Fs) Nov 17, 2009...
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This note was uploaded on 03/06/2010 for the course CS 9339 taught by Professor Gries during the Fall '09 term at Cornell.
 Fall '09
 GRIES

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