Subclass 1/047: Details of electrophonic musical instruments (keyboards applicable also to other musical instruments G10B, G10C; arrangements for producing a reverberation or echo sound G10K 15/08) Means for controlling the tone frequencies, e.g. attack or decay; Means for producing special musical effects, e.g. vibratos or glissandos by additional modulation Continuous modulation by acousto-mechanical means, e.g. rotating speakers or sound deflectors