Analysis of information sources in references of the Wikipedia article "Violin" in English language version.
In the case of string instruments, however, not only are they strongly directional, but the pattern of their directionality changes very rapidly with frequency. If you think of that pattern at a given frequency as beacons of sound, like the quills of a porcupine, then even the slight changes in pitch created by vibrato can cause those quills to be continually undulating.
The effect can be visualized in terms of a number of highly directional sound beacons, all of which the vibrato causes to undulate back and forth in a coherent and highly organized fashion. It is obvious that such a phenomenon will help immensely in fusing sounds of the differently directed partials into a single auditory stream; one may even speculate that it is a reason why vibrato is used so universally by violinists—as compared to wind players, from the sound of whose instruments directional tone color is generally absent.
Accordingly, the sound level of each harmonic will have a periodically fluctuating value due to the vibrato.
Accordingly, the sound level of each harmonic will have a periodically fluctuating value due to the vibrato.
In the case of string instruments, however, not only are they strongly directional, but the pattern of their directionality changes very rapidly with frequency. If you think of that pattern at a given frequency as beacons of sound, like the quills of a porcupine, then even the slight changes in pitch created by vibrato can cause those quills to be continually undulating.
