House hears bill to establish minimum sound levels for vehicles

We've reported on the silent dangers of hybrids before, and it appears that word of their possible threat to blind people has made it to the halls of Congress. A bill is being introduced today in the House of Representatives that calls for the U.S. Department of Transportation to study whether or not the feds need to regulate a minimum sound level for all cars and, if so, what that minimum should be. If passed, the entire auto industry would have two years to comply. The issue revolves around blind people not being able to hear hybrids while they're running solely on battery power, since they produce much less noise than a normal car with an internal combustion engine. We've heard no reports, however, of hybrids being involved in accidents with pedestrians where the vehicle's silent operation was at fault, but clearly there are many who would like to keep it that way.
The state of Maryland actually passed similar legislation last month, and the industry's own Society of Automotive Engineers already has a task force studying whether or not the decibel level, or lack thereof, produced by hybrids is something we should be worrying about.

Our question is that if such a bill were passed, what technology would automakers use to increase the sound a hybrid makes while running on battery power? Might we hear hybrids with external speakers pumping out the soundtrack of a fossil fuel-burning V8?

[Source: Automotive News, sub. req'd]