Pitch bending

We now know how to specify the pitch of a sound, whether it falls on one of the scale degrees or not (see Extra-scalar pitch), so long as the pitch remains constant throughout the duration of the sound (i.e. until the next onset). With some instruments, that is bound to happen: most harps, xylophones, and keyboard instruments are incapable of altering the pitch except by distinct steps (i.e. with a new onset; see Articulation and melisma). But many other instruments, including electric guitars, saxophones, the violin family, and most Indian melodic instruments, as well as the human voice, routinely use “bends” of pitch as part of their expressive technique. This can include, for example, “vibrato” (a more or less narrow and rapid fluctuation of pitch), “portamento” (moving between two distinct pitches by a gradual slide rather than a discrete pitch step), and approaching or leaving a distinct pitch by a slide, either up or down.

Clearly, none of these techniques can be captured by our standard rotated T symbol with its straight, horizontal “stem.” Instead, global notation specifies pitch bends by making the stem sloped or curved.

For example, the theme tune of the Warner Brothers’ “Looney Tunes” cartoons begins with a Hawaiian guitar sliding up in pitch, indicated here by a diagonal stem.





(Notice the extra-scalar pitches in the melody, too.)

Just as the stem of a rotated T symbol doesn’t always have to be horizontal, it also doesn’t always have to be straight. The actual pitch contour of a sung melody is often more accurately represented by a series of curves than by straight lines and angles.

Take, for instance, the American gospel hymn “When the Saints Go Marching In.” Transcribed directly from sheet music in staff notation, the melody might look very angular.



But in actual performance, the pitch might be constantly bending and oscillating. This can be captured by sound analysis software such as Praat, which can produce an accurate graph of pitch against time (see Producing a pitch-time graph).





The melody line may look very different from all our previous examples, but the score is read in exactly the same way. The grid lines show where the scale degrees and beats are, and the melody line is crossed by a short vertical line (equivalent to the “top” of a rotated T symbol) wherever there is a new syllable in the lyrics. (All these straight lines have been added manually to the pitch-time graph produced by Praat.) Thus, the melody line still consists of a series of rotated T symbols, it’s just that the “stem” of the Ts may be curved or wavy.

A graph like this reveals many subtleties in the singer’s technique. For instance, most notes have some vibrato, but the width of the vibrato is not constant: on short notes it is narrow, but on longer notes it tends to get wider as the note goes on. The scale degrees are evidently only a loose framework for this singer: sometimes they are approached by a “swoop” from below, other times they are left by an upward bend although the melody then descends. All these pitch bends are difficult to specify in staff notation, but in global notation they can either be captured with the precision of computer software or drawn impressionistically by hand.

(Whether this is actually useful to a singer wanting to learn the melody is another matter, but we can always use a simplified score such as our previous example if that is found more practical.)

Pitch bending, however, raises another issue for global notation. Our symbols emphasize the onset of each sound; but when pitch moves by slides rather than distinct steps, it may not always be clear exactly where a new “onset” occurs. To decide that, we need to consider the different ways in which the onset of a new sound may be “articulated.”

Next: Articulation and melisma


Sources of audio:

Warner Brothers, “Looney Tunes” theme, from All Your Favourite Cartoon TV Theme Tunes, We Love Digital CD, ASIN: B0784Z8HSW, track 5.

“When the Saints Go Marching In”, sung by soloist of The Plantation Singers, www.youtube.com/watch?v=Zscv3s1d5wk



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