Having read through much of the final rule document,
http://www.nhtsa.gov/staticfiles/rulemaking/pdf/QuietCar_FinalRule_11142016.pdf
I'm left with mixed thoughts. My LEAF has a noisemaker (aka Vehicle Sound for Pedestrians). Having experimented with it, the LEAF is otherwise eerily silent at very low speeds. The VSP makes a sound most would think is coming from the inverter / gearing (and perhaps a brake pad rubbing). The backup chime, though, is more annoying on a quiet evening than useful, and I can see why there is a disable button for the sounds effects, at least outside the US market. Neighbors sleeping with windows open at night will not appreciate the backup chime.
The new rule dispenses with the requirement for sound frequency to increase with vehicle speed... instead it is sound amplitude (loudness). Additionally, there is a requirement for an idle sound when the car is on, but not in Park, as a warning that the vehicle could move at any time. I have experienced the latter problem with the LEAF in having to roll down my window and warn someone standing next to my car chatting with the driver of the car in the next parking slot, "Excuse me, I need to back out..." Of course, that could still happen, even with a sound effect.
Manufacturers are given some latitude in how to meet the requirements. Only frequency bands, loudness, and conditions are set, but the actual sound effects, textures, and even method of creating them (synthesized using a speaker or natural tuning of the drive system) are open. The smart manufacturers will use this as an opportunity to create appealing signature sounds for their various models.
While I look forward to the day when crossing a 7 lane intersection on foot is no longer an experience of obnoxious noise, waste heat, and exhaust fumes... I'm not so sure the cacophony of "idle tones" will be a pleasant thing.