Roger J. Hanson
Phys. Dept., Univ. of Northern Iowa, Cedar Falls, IA 50614
Frederick W. Halgedahl
Univ. of Northern Iowa, Cedar Falls, IA 50614
Knut Guettler
Norwegian State Acad. of Music, P.B. 5190, Majorstua, 0302 Oslo, Norway
With a bow force greater than the Schelleng maximum and careful control, it will be demonstrated that it is possible to produce sounds on a violin of definite pitch ranging from approximately a musical third to a twelfth or more below the normal pitch. The lowered pitch is in agreement with the fundamental frequency of the observed harmonic series. The fundamental itself is very weak if the sounds are produced on the open G string. Mari Kimura has utilized the effect in performances [New York Times, 21 April 1994, p. B3, and Strings, Sept./Oct. 1994, 60--66]. These anomalous low frequencies (ALF) occur when the bow force is great enough to prevent the Helmholtz kink from triggering the normal release of the string from the bow hair. As a result of pronounced bow-nut and bow-bridge reflections there is at the bow a very complex string waveform, some portion of which regularly triggers the slipping of the string. ALF can also be produced on a bowed string mounted on a steel beam, where the motion is detected optically. Computer simulation is used to show how a string can be forced to vibrate at frequencies lower than the natural fundamental frequency of the string.