How do they make Vespas so quiet?

I have an eBike w/ a rear hub motor, a trike I'm converting to an eTike, and a Townie I bought that I'm considering putting a small hub motor on the front (even though I don't think I'll like a front motor, but it's cheap and easy). So obviously, now I need a bike that is powered by something else, LOL.

The thing with eBikes is that unless you empty the bank account, they're heavy. Bike IC engines are light, but loud. Except Vespas. I remember a friend who had one in high school and it was super quiet even though it had a 2 stroke engine, I think. How do they get those things to run so quietly? Is it because the motor is under all that bodywork? His muffler was smallish, so it couldn't have been that. The 2 stroke motorcycles I owned could be heard in the next county.

http://modernvespa.com/forum/topic85166

2 strokes are actually quieter than 4 strokes at any distance cuz the emission spectrum is higher frequency duh everyone knows that.

Less power, no resonant (bell, basically) chamber, muffling airbox and big muffler are the tickets to making a quiet combustion engine. You're asking some really strange questions though I must say.

The size of a muffler is not the only consideration. The thickness of the exhaust tube metal and in the muffler shell also play a part.

Also the number of baffles in the muffler and their specific shape affects the amount of transmitted noise. The bodywork covering up everything is also helpful in dampening any noise.

Some customers want a louder muffler, and also, making a small muffler very quiet can be more expensive as far as design and construction.

I have never heard a 2 stroke engine that was quieter than a 4 stroke engine, all things being equal. Except for the Vespas. And I've owned maybe 20 or 30 motorcycles in my life time. 2 strokes don't have valves or an exhaust cycle, so you get a lot of noise that isn't there in a 4 stroke engine. They're firing the spark plug(s) on every cycle rather than on every other cycle, so twice as many firings. They also need free flowing mufflers (think expansion chambers) and if you muffle them they poop out on power.

Don't feel bad. To some people, the whole world is strange :]

It took me forever to get this information, but the reason why Vespas are so much quieter than other 2 strokes is because A- the engine is under a cowl (which I thought might help), and B-the motor/rear suspension is mounted on rubber mounts like in a car. They're called "Piaggio silent blocks", and this keeps the vibration and noise of the motor from being amplified by the scooter's chassis and bodywork.