Just bought a cheapo box fan, which we use in a window at night to draw in cooler outside air. However, even at the slowest of its 3 speeds, the fan is too noisy. I'd like to make it less noisy, which I think the best way would be to make it turn slower. I'm wondering if it would be possible to wire in a resistor in series with the motor to accomplish that. If so, what would be the correct specs on the resistor?

thx, H