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Netflix vice president of product Todd Yellin said as much during an interview for the Twenty Thousand Hertz podcast, explaining that there was actually a shortlist of sounds that were also considered including the sound of bubbles underwater, as well as goats bleating.

Thank goodness none of these made it, but rather the "ta dum" sound. 

It might also be interesting to know that this iconic Netflix intro is the sound of a wedding ring hitting against a cabinet.