The Jew's harp is probably the world's best known mouth cavity instrument, especially considering the variations and diverse cultures in which it appears. It is certainly not the only instrument to use the player's mouth and throat to control pitch. Nor is it the world's oldest mouth instrument. The Jew's harp is almost certainly pre-dated by the mouth bow and didjeridu. More recent innovations which fit in the mouth cavity instrument category include the nose whistle (Trophy Music's Humantone) and my own percussive instrument, the Clackamore. I will limit this article to these five instruments although other sub-classes exist. (Input in this area would be greatly appreciated.)

Each of these instruments has a unique sound. The common element, the oral resonance, and tongue shifting comes through in each making them audibly identifiable as mouth cavity instruments. How the mouth, throat and lungs are employed varies. The following chart shows the 5 instruments and a variety of features. From this chart, it can be seen that while all these instruments use variations in mouth cavity size and shape, the way each is used varies. This in turn creates the unique sound of each.

Harmonics

Most musical instruments are recognized by the presence and relative intensity of their harmonic series. This is why an oboe sounds different that a clarinet. One notable exception is the flute family which produces a nearly pure pitch without an identifying harmonic series. Certain elements of timbre and richness are still present which allow us to tell a silver from a tin whistle.

Instruments in the mouth cavity family emphasize the harmonics individually, thus the tones are pure, but with the drone (lowest tone and all harmonics) sounding under the desired pitch. This result is most prevalent with the harp and mouth bow, and non-existent with the Clackamore and nose whistle.

The didjeridu, while usually a drone with harmonic overtones, can also be played as a melody instrument. I have a didj which produces an E flat as its normal lowest tone. By opening my throat and essentially adding to the pipes length, I can pull this tone down through a chromatic scale to an E flat one octave lower than the normal drone. Harmonic accents can still be produced over the notes, however, they are most prevalent and easily manipulated with the highest notes. Circular breathing is only possible in the highest notes as the lower notes require my throat be open, making it impossible to "squirt" out air with my mouth while breathing in through my nose.

Harmonics are the goal of mouth cavity instrumentalists and an understanding of the harmonic series can be very helpful. Harmonics, alsocalled overtones, have a mathematical relationship to the lowest tone produced by whichever vibrating system is employed. I will start with the string of a mouth bow as this is the most stratight forward example in this group of 5 instruments.

A string produces a certain pitch depending on its length, tension and mass (thickness). Let's say our string is tuned to vibrate 100 cycles each second (cps), which is a ridiculously low pitch, but a great number with which to work. The harmonic series of this string will contain pitches whose frequency is a multiple of the open pitch of 100 cps. Thus, the first overtone (known harmonically as the 2nd) has a pitch of 200 cps, the next a pitch of 300 cps, then 400 cps, 500 cps, etc. Theoretically, this multiplication of the lowest tone goes on infinitely. In practice, harmonics usually can't be utilized past about the 16th.

It is important to realize that several of these harmonics are, in fact, octaves of the base frequency. Doubling or halving a frequency produces octaves of that frequency. By virtue of this doubling, the pitch of 100 cps, when doubled to 200 cps, is the octave. Doubling again to 400 cps, then 800 cps and 1600 cps are also octaves.

BITS BETWEEN

Of great importance to the mouth cavity instrumentalist are the notes between the octaves. There are no notes between the octave of the base note and the 2nd and only one note between the 2nd and 4th. Between the 4th and 8th, three notes are available and between the 8th and 16th, seven notes. By virtue of this relationship, it can be seen that melodies are most easily found between the 8th and 16th harmonics. Unfortunately, most mouth cavity instruments produce only weak tones in this higher register. These factors create limited melodies. However, as a dedicated player, I am fascinated by those notes which are available. The Jew's harp has the ability to cheat out a few extra notes and the mouth bow stays very close to the harmonic scale. This is due to very different vibrating systems.

Some mouth cavity instruments are not restricted by a harmonic series. The Clackamore and nose whistle will produce a tone with any mouth size. The Clackamore goes even further in that the throat can be used to add even more depth to the sounds of this instrument. This is not possible with the nose whistle because air must pass out the nose to power the whistle so the throat must be kept closed.

GOING FURTHER