Passage: In 1961, MGM revived the Tom and Jerry franchise, and contracted European animation studio Rembrandt Films to produce 13 Tom and Jerry shorts in Prague, Czechoslovakia. All were directed by Gene Deitch and produced by William L. Snyder. Deitch himself wrote most of the cartoons, with occasional assistance from Larz Bourne and Eli Bauer. Stěpan Koniček provided the musical score for the Deitch shorts. Sound effects were produced by electronic music composer Tod Dockstader. The majority of vocal effects and voices in Deitch's films were provided by Allen Swift.Deitch states that, being a "UPA man", he was not a fan of the Tom and Jerry cartoons, thinking they were "needlessly violent". However, after being assigned to work on the series, he quickly realized that "nobody took [the violence] seriously", and it was merely "a parody of exaggerated human emotions". He also came to see what he perceived as the "biblical roots" in Tom and Jerry's conflict, similar to David and Goliath, stating "That's where we feel a connection to these cartoons: the little guy can win (or at least survive) to fight another day."Since the Deitch/Snyder team had seen only a handful of the original Tom and Jerry shorts, and since the team produced their cartoons on a tighter budget of $10,000, the resulting films were considered surrealist in nature, though this was not Deitch's intention. The animation was limited and jerky in movement, compared to the more fluid Hanna-Barbera shorts. Background art was done in a more simplistic, angular, Art Deco-esque style. The soundtracks featured sparse and echoic electronic music, futuristic sound effects, heavy reverb, and dialogue that was mumbled rather than spoken. According to Jen Nessel of The New York Times, "The Czech style had nothing in common with these gag-driven cartoons."Whereas Hanna-Barbera's shorts generally took place in and outside of a house, Deitch's shorts opted for more exotic locations, such as a 19th-century whaling ship, the jungles of Nairobi, an Ancient Greek...

Question: Name one type of effects that these gag-driven cartoons exhibited?
futuristic sound effects