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Topic: Dale Pond
Collected Articles Section: Harmonics, Partials and Overtones Table of Contents to this Topic |
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Some call harmonics partials and some call partials harmonics. Any division of a frequency into discrete smaller parts is EITHER a partial or a harmonic depending on whoever is speaking. In my writing I refer to these derivatives as HARMONICS if divisible by two (even) and PARTIAL for everything else. But then that is the Aquarian in me efforting to be more precise in my communications. Another term not as often used is "OVERTONE". This term is more general and may be used in a general sense. The study of overtones, partials and harmonics is a fascinating one. There are additive, subtractive, multiples and divisions all contributing to a myriad of seeming complexity in all acoustic phenomena. There are simple, complex and compound tones. No single tone (sound) exists by itself, without its progeny. Beats are an example of subtractive (Difference) tones*, of which there are five basic types**. Additive harmonics can sum (Summation Tones) into increases in power, for example. Get the old books and learn about the ALIVE and DYNAMIC world of unseen vibrations/oscillations. There is FAR MORE to sound than simple "frequency". "Difference tones were discovered by Sorge in 1745 and again independently by Tartini in 1754. By sounding two tones a fifth apart, the tone an octave below the lower note is resonated. It is in general true that when any two or more pure tones which are sounded simultaneously happen to be harmonics of the same fundamental note, then the ear adds this fundamental note and many of its harmonics, of its own accord - a result of tremendous importance in all branches of pure and applied acoustics. If the pure tones are all the odd-numbered harmonics of a fundamental note, then the ear of its own accord adds all the even harmonics. If the two pure tones differ only slightly in frequency, then their "difference tone" has the same frequency as the BEATs, so that as the two original tones approximate to one another, their difference tone degenerates into beats, while their SUMMATION TONE approaches to their second harmonic. Difference tones are usually concordant, summation tones discordant, with the tones that produce them; these being the KEY NOTE or ROOT. These two tones are always present simultaneously in all tones, the Difference tones being louder and therefore Dominant of the two. Difference tones can be used to create unlimited Physics depth of tones, ultimately appearing as beats when the two original tones are brought more nearer coincidence. Difference tones are positive and DOMINANT, summation tones are Negative." [John Tyndall, 'Sound'] **1) Beat Dissonance between Fundamentals; 2) Between one fundamental and partial of the other; 3) Between overtones; 4) From the occurrence of Differentials; 5) From the occurrence of Summation Tones. then there are the secondary, tertiary, etc. of all simple, combination and compound tones. |
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