1 / 46

# L 12 Fourier Synthesis, Fourier Analysis, and String Instruments

L 12 Fourier Synthesis, Fourier Analysis, and String Instruments. Fourier Synthesis Demo- PhET ( Physics,Fourier ). library.thinkquest.org/19537 add f 3 ,f 5 ,f 7 ,f 9 to hear f 1, a false fundamental. Fourier Analysis Demo- Raven- Lite. Analysis of Swirling Tube (open at both ends).

## L 12 Fourier Synthesis, Fourier Analysis, and String Instruments

E N D

### Presentation Transcript

1. Fourier SynthesisDemo- PhET (Physics,Fourier)

2. library.thinkquest.org/19537add f3,f5,f7,f9to hear f1, a false fundamental

3. Fourier AnalysisDemo- Raven-Lite

4. Analysis of Swirling Tube (open at both ends)

5. Re the 7th harmonic,in the tempered scale, the dominant 7th should be 2 10/12 times the frequency of the tonic below=1.78 times the frequency of the tonic below it.The tonic is 4f1. The ratio of 7 f1 to4 f1 is7/4 =1.75So this note is a very flat dominant 7th, and should not be played as an harmonic in this series. A brass player playing this series of harmonicsmust play an harmonic of another note to play this note in tune.

6. For the whirly tube,f1= v/λIf the tube length L is 1 m, thenf1 =v/2L =344/2= 177Hzf2= 2f= 344 Hz, f3 = 3 f1= 531 Hzf4=4f1=708 Hz, etc.Compare to measurements…

7. Symphony InstrumentsGo to dsokids.comthen click on one of the books called Instruments

8. String Instruments

9. Resonance

10. Demo Tuning Fork on Table, on Resonator

11. ct.10.1.10a A string on an instrument plays an A (440 Hz) when plucked. If you put your finger down one half of the way along the string, and then pluck, you are mostly likely to hear… A: Still 440 Hz B: 220 Hz C: 880 Hz D: Something entirely different

12. ct.10.1.10a A string on an instrument plays an A (440 Hz) and a number of higher harmonics when plucked. If you put your finger down one half of the way along the string after it has been plucked, you are mostly likely to hear… A: Still 440 Hz B: 220 Hz C: 880 Hz D: Something entirely different

13. ct.10.1.10b2 A string on an instrument plays an A (440 Hz) when plucked. If you put your finger down hard (pushing the string to the fret), one third of the way along the string, and then pluck the longer side, you are mostly likely to hear… A: 3*440Hz B: (1/3)*440 Hz C: 3/2 * 440 Hz D: 2/3 * 440 Hz E: Something entirely different

14. Electric guitars can have several pickups to detect string motion. You can flip a switch to activate single pickups or combos. Which pickup would you activate to make your music sound “crisper” (i.e. pick up more of the higher pitch frequencies?) 10.1.10c A. B. C. D. Some combo / no diff

More Related