2003 GMC Envoy Owner's Manual - Page 198

Setting the Tone (Bassmreble) AUDIO: Push and release the AUDIO knob until BASS or TREB appears on the display. Turn the knob to increase or to decrease. The display will show the bass or treble level. If a station is weak or noisy, you may want to decrease the treble. To adjust the bass and treble to the middle position, push and hold the AUDIO knob. The radio will produce one beep and adjust the display level to the middle position. To adjust all tone and speaker controls to the middle position, push and hold the AUDIO knob when no tone or speaker control is displayed. The radio will produce one beep and display ALL with the level display in the middle position. AUTO TONE (Automatic Tone): Press this button to choose bass and treble equalization settings designed for country/western, jazz, talk, pop, rock and classical stations. To return the bass and treble to the manual mode. press and release the AUDIO knob. If your vehicle has the Base@ radio, your audio system allows you to choose from four different equalization settings: talk, driver, normal and spatial. These settings can be used while listening to the radio or the CD player. Press the AUTO TONE button to select your choice. TALK: This setting makes spoken words sound very clear. When listening to non-musical material such as news, talk shows, sports broadcasts and books on tape. DRIVER: This setting gives the driver the best sound quality. NORMAL: This setting enhances the stereo effects. SPATIAL: This setting makes the listening space seem larger. The radio will save separate AUTO TONE settings for each preset and source. 3-73