2008 Toyota Prius Owners Manual - Page 292

3-3. Using the audio system Setting DSP The following features can be set as desired by touching screen. Type B only on the n Turning Automatic Sound Levelizer (ASL) Type A Touch . ASL automatically adjusts the volume and tone quality according to the noise level as you drive your vehicle. Type B Touch , or . ASL adjusts the volume and tone quality according to the noise level as you drive your vehicle. 264 PRIUS_U_(L/O_0802)