disguiser

A voice disguiser alters a person’s voice to protect their anonymity.

[…] out of a caue in the said Rock came .x. knightes, armed at all poyntes, & faughte together a fayre tournay. And when they were seuered & departed the disguysers dissended from the rock & daunced a great space: & sodeynly the rocke moued & receaued the disguysers, & ymediatly closed agayn.