PITCH TUNE: Detailed Information

by Archer Endrich

Key Features of the CDP PITCH set

In general, these functions are designed for sounds with fairly clear pitch content, rather than complex and noisy sounds.
Sounds with clear pitch content have partials which are 'harmonically' related, that is, the partials are integer multiples of the fundamental (multiplied by whole numbers, not fractions; e.g., 2, 3, 4, 5 etc.).
The function ALTHARMS is a typical example of this set, removing either the odd or the even harmonics.
Similarly, TRANSP, the pitch transposition function in this set, transposes while keeping harmonic relationships. Thus the original tone of the sound is less changed by the transposition process.
PICK provides a number of interesting options, such as retaining the partials belonging to the harmonic (overtone) series.

Some possible musical results with PITCH TUNE

This example uses a clear pitch produced by a French Horn. After the tuning operation, we clearly hear the chord we defined. PITCH TUNE is very effective in producing a clear, chordal result.
When applied to a complex sound, such as the running water used in another of the examples, tuning does take place, but is heard as a soft chord 'behind' the foreground sound of the water. Thus, even with the same settings, many partials are not affected.
One interesting application is to use this tuning with source material that contains both pitched and unpitched features. The pitched sounds come through as clear chords, while the unpitched, though less affected, is nevertheless still 'warmed' by the tuning process.
Note that this function is limited to one chord definition. It does not handle changing chords as does FILTER VARIBANK, used in the example for FILTERS.

Other forms of tuning in CDP

The main alternative to PITCH TUNE are the various FILTER programs, also very effective, with time-varying frequency band definitions, Q etc. Considerable clarity in the tuning can be achieved with the FILTER programs, but only when the Q is set rather high. This can produce more resonance than desirable (your speakers will notice). PITCH TUNE creates the clarity (with pitched sounds) without a resonance by-product.
One should also mention the functions which move harmonic relationships towards inharmonic ones, such as STRANGE SHIFT, which moves partials by a fixed multiplier. This squeezes or expands the partials in a linear fashion, thus breaking the exponential nature of harmonic relationships (octaves double the previous frequency).
One would think that PITCH CHORD would produce results similar to PITCH TUNE, but this is not the case. Some tuning occurs due to the internal transpositions taking place, but it is, in my experience, a rougher effect, dealing with the whole spectrum rather than focusing on the specified pitches as does PITCH TUNE.

General observations

Let's go back to this idea of locating the Peak Energy Bands (PEB) within the spectrum of the sound. SPECINFO PEAK gives us the following information in a readable text file format (I set it to look at each 10^th of a second.):

WINDOW	0.0000	0.0987	:PEB 	 50.0000	TO      70.7107
WINDOW	0.0987	0.1974	:PEB 	400.0000	TO	565.6854
WINDOW	0.1974	0.2961	:PEB 	800.0000	TO    1131.3708
WINDOW	0.2961	0.3947	:PEB 	800.0000	TO    1131.3708
WINDOW	0.3947	0.4934	:PEB 	400.0000	TO	565.6854
WINDOW	0.4934	0.5921	:PEB 	400.0000	TO	565.6854
WINDOW	0.5921	0.6908	:PEB 	400.0000	TO	565.6854
WINDOW	0.6908	0.7895	:PEB 	400.0000	TO	565.6854
WINDOW	0.7895	0.8882	:PEB 	400.0000	TO	565.6854
WINDOW	0.8882	0.9868	:PEB 	400.0000	TO	565.6854
WINDOW	0.9868	1.0855	:PEB 	400.0000	TO	565.6854
WINDOW	1.0855	1.1842	:PEB 	400.0000	TO	565.6854
WINDOW	1.1842	1.2829	:PEB 	400.0000	TO	565.6854
WINDOW	1.2829	1.3816	:PEB 	400.0000	TO	565.6854
WINDOW	1.3816	1.4803	:PEB 	400.0000	TO	565.6854
WINDOW	1.4803	1.5790	:PEB 	400.0000	TO	565.6854
WINDOW	1.5790	1.6776	:PEB 	800.0000	TO    1131.3708
WINDOW	1.6776	1.7763	:PEB 	400.0000	TO	565.6854
WINDOW	1.7763	1.8750	:PEB 	400.0000	TO	565.6854
WINDOW	1.8750	1.9737	:PEB 	400.0000	TO	565.6854
WINDOW	1.9737	2.0724	:PEB 	400.0000	TO	565.6854
WINDOW	2.0724	2.1711	:PEB 	400.0000	TO	565.6854
WINDOW	2.1711	2.2698	:PEB 	400.0000	TO	565.6854
WINDOW	2.2698	2.3684	:PEB 	400.0000	TO	565.6854
WINDOW	2.3684	2.4671	:PEB 	400.0000	TO	565.6854
WINDOW	2.4671	2.5658	:PEB 	400.0000	TO	565.6854
WINDOW	2.5658	2.6645	:PEB 	400.0000	TO	565.6854
WINDOW	2.6645	2.7632	:PEB 	400.0000	TO	565.6854
WINDOW	2.7632	2.8619	:PEB 	400.0000	TO	565.6854
WINDOW	2.8619	2.9605	:PEB 	400.0000	TO	565.6854
WINDOW	2.9605	3.0592	:PEB 	400.0000	TO	565.6854
WINDOW	3.0592	3.1579	:PEB 	400.0000	TO	565.6854
WINDOW	3.1579	3.2566	:PEB 	400.0000	TO	565.6854
WINDOW	3.2566	3.3553	:PEB 	400.0000	TO	565.6854
WINDOW	3.3553	3.4540	:PEB 	400.0000	TO	565.6854
WINDOW	3.4540	3.5527	:PEB 	400.0000	TO	565.6854
WINDOW	3.5527	3.6513	:PEB 	400.0000	TO	565.6854
WINDOW	3.6513	3.7500	:PEB 	400.0000	TO	565.6854
WINDOW	3.7500	3.8487	:PEB 	400.0000	TO	565.6854
WINDOW	3.8487	3.9474	:PEB 	400.0000	TO	565.6854
WINDOW	3.9474	4.0461	:PEB 	400.0000	TO	565.6854
WINDOW	4.0461	4.1448	:PEB 	400.0000	TO	565.6854
WINDOW	4.1448	4.2434	:PEB 	400.0000	TO	565.6854
WINDOW	4.2434	4.3421	:PEB  1600.0000	TO    2262.7417
WINDOW	4.3421	4.4408	:PEB 	400.0000	TO	565.6854
WINDOW	4.4408	4.5395	:PEB  1600.0000	TO    2262.7417
WINDOW	4.5395	4.6382	:PEB 	400.0000	TO	565.6854
WINDOW	4.6382	4.7369	:PEB 	400.0000	TO	565.6854
WINDOW	4.7369	4.8356	:PEB 	400.0000	TO	565.6854
WINDOW	4.8356	4.9342	:PEB 	400.0000	TO	565.6854
WINDOW	4.9342	5.0329	:PEB 	200.0000	TO	282.8427
WINDOW	5.0329	5.1316	:PEB 	400.0000	TO	565.6854
WINDOW	5.1316	5.2303	:PEB 	800.0000	TO    1131.3708
WINDOW	5.2303	5.3290	:PEB 	800.0000	TO    1131.3708
WINDOW	5.3290	5.4277	:PEB 	800.0000	TO    1131.3708

This shows us that the main energy band is, throughout the duration of the sound, between 400 Hz (just under the A above Middle C) and 565 Hz (between High C# and High D). Most of the pitches of our tuning template are in fact outside this band, but the range of tuning pitches includes the band, which appears to be sufficient. The full range of frequencies in the display is 200 to 2262, which does cover most of the pitches in the tuning template. (The 50 Hz frequency with which the display begins was in fact set in the dialogue box.)

Last updated: 5 December 2003