Perception of Virtual Notes While Tanpura Playing

Abstract

One unusual phenomenon observed by many musicians and reported by few researchers is the virtual notes perceived in tanpura drone. Virtual notes are complex tones with missing fundamental. Characteristically one perceives a pitch for such tones which correspond to the missing fundamental. A musical tone can be visualized as a combination of many simple periodic waves or partials, each having its own fundamental frequency of vibration and amplitude. Normally a complex tone has its fundamental and many higher harmonics. For such notes the perceived pitch corresponds to the spectral pitch which is present. Normally a complex tone has its fundamental and many higher harmonics. Musical signals are often found deprived of the fundamental component but not of the perceived pitch. This is the case with tanpura. In tanpura the fundamental is very weak and is often inaudible. Sometime it so happens that the harmonics sends strong signal and the pattern theory of cognition of pitch cognitively dominates and we hear virtual notes. Also often these virtual notes refer to a pitch to which none of the strings are tuned. It then becomes a phenomenon asking for attention. It becomes interesting to investigate these phenomena in some detail to arrive at a good model for relating the virtual note to the harmonic pattern. The present chapter deals with the virtual notes heard by a senior musician in a well tuned tanpura and an attempt to explain those virtual notes objectively.