Chapter 16 Fourier Analysis, Normal Modes and Sound
*What is Fourier analysis?
page 16-3 Harmonic Series
The information we need from this section was covered in chapter 15.
The following sections may contain interesting material for you. It is not core physics material so we will skip it.
page 16-4 Normal Modes of Oscillation We will skip this section.
page 16-6 to 14 Fourier Analysis We will skip this section.
page 16-15 to 17 The Human Ear We will skip this section.
page 16-18 Stringed Instruments We will skip this section.
page 16-19 Wind Instruments
At last! Some material that is easy to discuss. We will cover this section, but we will only deal with simple wind instruments, a pipe open at one end and a pipe open at two ends.
Name the part of the standing wave that is located where the dotted lines cross in Figure 39.
Why is there a node at the left end of the pipe in Figure 39 b)?
Which pipe is analyzed in a very similar way to our analysis of the standing wave on a string that had nodes at both ends of the string?
We will develop the formulas for the frequencies of the harmonics for both the open and closed pipes.
page 16-22 Percussion Instruments Another interesting section that we will skip.
page 16-24 Sound Intensity
If a tree falls in the middle of a forest does it make a sound?
Can you hear loud and soft sounds?
Why?
Intensity watts/m2
The loudness of a sound is measured in decibels. β (dB) = 10 log10 (I / I0 )
I is the intensity of the wave. I0 is 1 X 10 –12 Watts/m2
Why do physicists use a logarithmic calculation for sound intensity?
What is the intensity range in human hearing on the decibel scale?
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