Confess to being a little puzzled by this quest for the perfect sound module .....
I am a newcomer to ebikes, but one of the things I dig the most is the near silence, especially when riding at night. And I've got a bunch of noisy ICE hotrods. I do understand the concern from a safety standpoint (oblivious pedestrians), but the same applies to my single-speed bicycles ..... I try to expect the unexpected.
Some time ago I was approached by the developer of an electric "hotrod dragster" project - he wanted a convincing ICE sound to accompany the fury of the electrically driven smokin' tires (I was a retired audio engineer with a long career in film FX). I tried to convince him that the kind of SPL he was envisioning would take a hell of a lot of ELECTRICAL power away from the primary go-fast goal ..... not to mention the weight and bulk of the reinforcement system. And you'd still be in danger of the "flea farting in a hurricane" situation, or maybe the playing card flapping against your spokes on your kiddee bike ....... ie ...... pathetic!
Mike