How to interpret these FFT results?

1. What does the FFT tell you?
2. How do you read frequencies in FFT?
3. What's the output of FFT?

What does the FFT tell you?

The "Fast Fourier Transform" (FFT) is an important measurement method in the science of audio and acoustics measurement. It converts a signal into individual spectral components and thereby provides frequency information about the signal.

How do you read frequencies in FFT?

The first bin in the FFT is DC (0 Hz), the second bin is Fs / N , where Fs is the sample rate and N is the size of the FFT. The next bin is 2 * Fs / N . To express this in general terms, the nth bin is n * Fs / N .

What's the output of FFT?

These frequencies actually represent the frequencies of the two sine waves which generated the signal. The output of the Fourier transform is nothing more than a frequency domain view of the original time domain signal.