I turned on the The Automated Sound Leveling (ASL) for the speakers in the radio menu and did not notice a difference in sound when I opened the windows, even though the car became more noisy from the wind. I wonder if it really works?
I thought it had more to do with car speed and rpm's. Stopping at a light would make it lower the volume. I don't know, never seemed to notice any difference either. Good question.
ASL adjusts the radio volume level based on vehicle speed. It does not monitor the inside or outside noise level. So, to notice a change in audio level, you will have to cross a speed threshold. The Mazda I currently drive has 2 threshold levels: 45 and 60MPH. I cannot speak for the Prius.
i thought it had something to do with inserting negative or white noise into the sound to mask engine/road noise?
I also notice a difference when the ASL is on. I don't think that there is any reason to turn it off.
I checked this out with different speeds. I tried to notice any difference from 30 , 40, 50, 60, 65 with windows closed. Had my wife in car as well (and she was very quiet-unusual, but she was helping me test). Both of us did not notice any difference in sound and I know that the ASL was on. I would figure that it would be based on feedback through the speaker somehow to level the sound, but either it is not working in my brand new Prius, or it doesn't work period.
I'm wondering if this is verifyable by watching the volume display. Set the volume to say, "10", from a dead stop. Accelerate up to 60 mph, tap the volume button and see if it has changed at all.
from my understanding, that is not how the ASL works. the volume stays the same, it does something to the sound levels to reduce backgroud noise or somehow magically disguise it look at those bose noise reducing headphones and think prius
