Averaging Short Time FFTs
Averaging Short Time FFTs
In order to determine a pitch as it is being played
in real time, a continuous
stream of FFTs will need to be taken. This series of overlapping
FFTs is called a spectrogram. Once a note has been played, the
FFT can be taken of a short time sample (n=4096). We will then
compare the short time FFT to pre-constructed template of each
note the violin can play. In order to construct each template,
we will take a spectrogram of a note we already know the pitch of,
and average the short time FFTs over the entire note. Below is one
such average. This average is not normalized, although first
normalizing each short time FFT and then averaging all of them
together may also yield a reasonable average.
Underneath the average is the varience, which should
be useful for estimating error. This variance is over a
note with vibrato, so it's not surprising that there is so much
variance around the harmonics.
BACK