 in Part One of Jet Fuel Formula the clarity of the voice cast  is noticeably better than in subsequent episodes, particularly the  voice performances of June Foray and Paul Frees; a close listen  finds that the studio echo of the session bleeds into the  soundtrack. For subsequent episodes the different soundtrack stock  used eliminated this echo. In addition, the voice casts  performances began changing, particularly William Conrads  narrations. Throughout Part One, Conrads narration is totally  straight, but in Part Two he began in inject a mild flamboyance to  his narration in keeping with the shows whimsical flavor, and as  the series continued his narration became ever more comically  melodramatic.