Complex sentence: In early modular synthesizers, each synthesizer component (e.g. LFO, VCF) can be connected to another component by means of a patch cable that transmits voltage, with changes in that voltage causing changes to one or more parameters of the component.
Split into simpler sentences: In early modular synthesizers each, synthesizer component (e.g. LFO, VCF, etc.) can be connected to another component by means of a patch cable that transmits voltage. Changes in that voltage cause changes to one or more parameters of the component.