Re: [Fwd: technical notes on data used by Martin Braun]

[Paul Boersma <paul.boersma@xxxxxxxxxx>]

>> Was the pitch contour presented as a continuous line, or was it
>> quantized in quarter semitones?
>
>Well, it was displayed as a series of frame-by-frame values, not as a
>continuous line. At the 16k sampling frequency that we used, the
>frame-by-frame values have a resolution of a quarter of a semitone.

Is it likely that the measured F0 values had a spacing of 1/4 semitone?
It seems more likely that they were expressed as an entire number
of samples per period. For instance, for an F0 of 200 Hz you would
get 16k/200 = 80 samples per period. In that vicinity, then, the
spacing is 1 sample per period, or 1.25%, or just below one quarter
of a semitone, which seems to be consistent with what Bob Ladd remembers.

However, if you "bin" such values into 1/4-semitone buckets,
you should control for the number of possible values that fit into
such a bucket. In the range 115-230 Hz, that number is 1, 2, or 3.
Of course, I don't expect any researcher to have overseen such
a correction, but it is interesting to see what results such mistake
would have led to. The following is a Praat script that generates
random F0 values between 115 and 230 Hz, and bins them according
to the above faulty criterion:

for bin from 10 to 57
   n'bin' = 0
endfor
for i to 10000
   f0 = randomUniform (115, 230)
   samplesPerPeriod = round (16000 / f0)
   f0_gipos = 16000 / samplesPerPeriod
   semitones = hertzToSemitones (f0_gipos)
   quarterSemitoneBin = round (semitones * 4)
   n'quarterSemitoneBin' = n'quarterSemitoneBin' + 1
endfor
echo Bin n
for bin from 10 to 57
   n = n'bin'
   printline 'bin' 'n'
endfor

In the bin range from 10 to 57 (that is, 48 bins = one octave),
we now find distinctive peaks at bin numbers
25, 27, 29, 31, 33, 35, 38, 41, 45, and 52.
Note that this series contains several subseries at distances
of 4, 6, or 8 bins (4 bins = 1 semitone).

Can the authors show us how they corrected for this sampling-and-binning
problem?

Does a reanalysis with a program that has an F0 measurement accuracy of,
say, 0.00001 Hz instead of 1/4 semitone, still lead to the reported result?

Best wishes,
   Paul
--

Paul Boersma
Institute of Phonetic Sciences, University of Amsterdam
Herengracht 338, 1016CG Amsterdam, The Netherlands
http://www.fon.hum.uva.nl/paul/
phone +31-20-5252385