Undertone series

Undertone is a term used in music or acoustics, but also possesses other physical vibrations and validity is called in that context also subharmonic.

The undertone may or subharmonics can be thought of the overtone series by mirroring the root or base vibration down. There are frequencies with integer division ratios of the fundamental. The undertones are tones (frequencies), for example, have the following frequency ratios to a root:

Clearly, one can imagine the formation rather than by dividing a string by their doubling, tripling, etc. explain. The overtones of a fundamental tone are exactly the sounds in their overtone supply the root occurs.

While the harmonics resonate more or less with any tone generator or musical instrument, the undertones do not appear in the frequency range of most instruments. For stringed instruments can they cause by excessive bow pressure. However, these are no undertones, but so-called " Anomalous Low Frequencies ", which are caused by slipping of the bow hair with the stick-slip effect. Undertones formed the basis in the constructed and played by Oskar Sala Mixturtrautonium. Lots of vibrating surfaces adjacent objects sometimes generate subharmonics. Better known are subharmonic in industrial processes such as ultrasonic applications ( ultrasonic cleaning equipment, ultrasonic welding horns ). They show up chirping and squeaking when applying to a lying beyond the range of audibility fundamental.

Example of the pitch A:

While it is clear from the first overtones of the fundamental tone of the sound - stock for the major chord, give the first overtones of the minor chord. The spread in the ( speculative ) theory of music school of thought, the minor triad is therefore a major triad to a mirror-symmetrical " sub sound " is called harmonic dualism:

Example of root C:

Harmonics are

This results from the first overtones of the C major chord CEG.

Undertones

This results from the first overtones of the F minor chord F -As -C.

In modern music there are always experiments to include the sounds with the 7-fold or one-seventh of the fundamental frequency with the harmonies. In the above example, the sound B, and D.

The numbering of the upper / lower tones is sometimes also made ​​so that the root itself is designated as number 1 and thus all the numbers are shifted by one. For integer ratios of the frequencies then one speaks of harmonics / subharmonics instead of upper / lower tones. This has the advantage that the powers of two are clearly visible in the numbers of harmonics. For example, in this nomenclature, the seventh harmonic would be the tone with the 7-fold frequency.