The technology of remote voice analysis is on it's 40th year.  Most operatives rarely talk aloud and if communication in unsecured locations is necessitated, it's best to talk in hushed tones and or near a sink with water running.  Running water is still unpatternable and thus cannot be negated by filtering.

Many quiet interrogations are in settings where direct connections for galvanic or direct thermal data gathering cannot be accomplished.  Voice Stress Analysis becomes the consideration of choice in a controlled setting without notification of subject.

It's been the common practice to not place much confidence in RARVSA but used as a gateway for further probing.  The hardcore believers themselves run a lot of water.