Understanding the result of the fft algorithm

1. What is the result of an FFT?
2. What does the FFT show?

What is the result of an FFT?

The FFT function returns the spectrum so that the DC (constant/average) value is first in the array. Use the function fftshift to adjust the array if you want it ordered −fs/2<f<fs/2.

What does the FFT show?

The FFT shows the two distinct frequencies of the individual pipes. These illustrations show the essential nature of the FFT. For a sine wave with a single frequency, the FFT consists of a single peak.