Page 40 - Summer 2007

Fig. 3b. DIFFDOT plot for “Fever.”
Fig. 3c. Close-up DIFFDOT plot for the pulse note events in “Fever.”
Subdivision of the meter in the time series plot is a four beat pulse phrase with six subdivisions of the pulse. Thus, the downbeat, backbeat and triplet tem- poral locations are marked by vertical lines. Finger snaps and conga drum beats land exactly on these time ticks. The precise clusters of note events on the pulse, backbeat, and triplet time lines in the DIFFDOT plot are evident. There is a general absence of note events on the quarter note line, just as there was in It Don’t Mean a Thing.
A very remarkable aspect of this recording can be seen in the close-up DIFFDOT plot (Fig. 3c) showing only the pulse of Ray Charles snapping his fingers on the backbeat. It is obvious from the normal DIFFDOT plots of Graceland and It Don’t Mean a Thing that the variations in the pulse event time deltas are much greater on those two samples than on Fever. The close- up shows that Ray Charles finger snap
time deltas are less than 5 milliseconds.
This means that the deviation from the canonical MB metronome beat times is less than +/- 2.5 milliseconds. Given the tight rhythmic style of this record- ing, and the fact that Ray Charles was one of the 20th cen- tury’s best musicians, we believe this DIFFDOT plot repre- sents an important data point regarding the limits of human
time perception and physical action.
work precision, this song is never boring and led to a sec- ondary defining feature of Swing (beyond inducing body movement). A 14 second loop made from this recording could play endlessly and after more than an hour, it still sounded incredibly fresh. A sample which becomes perceptu- ally tedious after only a few repetitions
almost certainly does not Swing. Beneath the excellent musicianship, there exists a strong triplet element to the rhythm. The conga drum plays around the backbeat which is marked precisely by Ray Charles’ finger snaps. About half of the conga note events are on triplet pickup beats before either the downbeat or the backbeat, with a few on triplets following these main beats. Unlike Graceland or It Don’t Mean a Thing, this sample shows virtually no rhythmic looseness. The conga, drums, finger snaps, and bass guitar are syn- chronized with each other to a precision of better than 15 milliseconds in almost all cases. Contrast this precision with Graceland’s consistent variations of 50 to 80 milliseconds, and It Don’t Mean a Thing’s somewhat random looking vari- ations in the 30 to 40 millisecond range. These are details that distinguish between loose and tight rhythmic styles. Figures 3, 3a and 3b show the famil- iar set of spectrogram, time series event plots, and DIFFDOT diagram.
Fig. 4. Spectrogram of pandeiro batida.
Fig. 4a. Time series plot of pandeiro batida.
38 Acoustics Today, July 2007