There are a number of EV1 videos on youtube. One I watched had a scene where they filmed it reversing out of a driveway and driving away. Didn't hear anything unusual while it was backing up. However another is this one:
At about 7:00, they demonstrate the pedestrian alert horn - which does have a distinctive warble.
Here is another vid with the reversing sound but the sound still isn't clean enough IMO. This is from the liveoilfree youtube channel, RIP. He was on Who Killed the Electric Car. About 49 seconds in. https://www.youtube.com/watch?v=YCBc8pL1SGc
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