For simplicity, the rudiments of Global Notation have been explained for the most part using examples in which only one pitch is sounding (or anyway notated) at a time. But of course, a great deal of music uses more than one pitch at a time - including the vast majority of Western music along with many other traditions - and we will often want to notate (for instance) a melody with a harmonic accompaniment, or two or more melodies played in counterpoint.
Any situation in which more than one pitch is sounding at a time will be called a “pitch combination.” The simplest kind of pitch combination to notate is “doubling,” in which a melody is simultaneously performed at more than one pitch level, usually one or more octaves apart, as for instance when men and women sing the same melody together.
Doubling can be notated without writing out all of the pitches that are actually sounding, simply by writing the melody at one pitch level and indicating the doubling with a marking at the beginning (see Wide pitch range).
Most other kinds of pitch combination will require writing more than one symbol for sounds of different specified pitches at the same point in time - which is to say, in horizontal space. In many cases, this can be done simply by writing multiple symbols into the pitch-time grid in the usual way. For instance, here is the beginning of Mozart’s “Turkish Rondo” notated in that way:
The appearance of symbols for sounds of specified pitch stacked one above another may be different from most of our previous examples, but no new principle is involved.
In some other situations, however, this straightforward approach is not ideal for various reasons, and alternative solutions are presented on separate pages within this section.
Sources of audio
Wolfgang Amadeus Mozart, Piano Sonata No. 11 in A Major, K. 331, third movement “Rondo Alla turca,” performed by Giancarlo Andretti, Maestro Music Distribution CD, ASIN: B01HUDF194, track 3.