The issue of the sound, or lack thereof to be specific, of hybrids, electric cars and everything in-between isn't likely to go away any time soon. The problem, as some see it, is that electric motors do not make the same kind of noise that internal combustion engines make, and this could be a problem for blind or deaf people. Is it a real concern? That's difficult to say until these types of vehicles really begin showing up on the roadways and people are interacting with them on a day-to-day basis. We've witnessed first-hand the fact that electric vehicles do indeed make noise, but is that sound enough to ensure the safety of pedestrians? We'll see.
In the meantime, engineers are considering all of their options when it comes to making artificial noises for their EVs and hybrids. For instance, the Volt's designers, led by Frank Weber, intend to add a driver-activated "pedestrian-friendly alert" to the Chevy Volt. The Star Trek-like (seriously) noisemaker would be turned on and off manually it seems. Of course, the Volt will indeed have an engine, but it won't always be running and may, in fact, hardly ever operate depending on its driver's habits. We look forward to seeing how this plays out.