The FFT - "An Audio Microscope"
John Siau provides a short tutorial to explain how FFT analysis can allow us to look at low-level details that would otherwise be hidden by the noise. He compares this to our own ability to hear individual tones that are well below the level of the ambient noise. He explains that our ears are about the equivalent of a 1024-point FFT.
Our APx555 audio test stations can acquire a 65,536-point FFT, allowing us to outperform the human ear by about 18 dB. This extreme resolution provides an "audio microscope" for detecting defects that are far too small to be audible. This gives us the ability to detect and eliminate these low-level details so that we can deliver products that are truly transparent to the human ear.
John delivers a word of caution regarding measurements: According to John he has had many experiences where he heard something but didn't see anything in the measurements. In every case, he eventually tracked it down with measurements. According to John; "the trick is that we don't always know what to measure".
