Jamieson, Fausset and Brown on Ecclesiastes 5:3

3. As much "business," engrossing the mind, gives birth to incoherent "dreams," so many words, uttered inconsiderately in prayer, give birth to and betray "a fool's speech" (Ec 10:14), [Holden and Weiss]. But Ec 5:7 implies that the "dream" is not a comparison, but the vain thoughts of the fool (sinner, Psa 73:20), arising from multiplicity of (worldly) "business." His "dream" is that God hears him for his much speaking (Mt 6:7), independently of the frame of mind [English Version and Maurer].

fool's voice--answers to "dream" in the parallel; it comes by the many "words" flowing from the fool's "dream."