2002 GMC Envoy Owner's Manual - Page 210

To set all tone and speaker controls to the middle position, press and hold the AUDIO control when no tone or speaker control is active. The radio will produce one beep and CENTERED will appear on the display. To set the treble, press the AUDIO control until TREB appears on the display. Turn the control to increase or decrease treble. When you use this control, the radio's tone setting will switch to custom. If a station is weak or noisy, you may want to decrease the treble. To set treble to the middle position, select TREB and press and hold the AUDIO control. The radio will produce one beep and set the display level to zero. To set all tone and speaker controls to the middle position, press and hold the AUDIO control when no tone or speaker control is active. The radio will produce one beep and CENTERED will appear on the display. AUTO EQ: This feature allows you to choose preset bass, midrange and treble equalization settings designed for country, jazz, talk, pop, rock and classical stations. The setting last chosen will appear on the display when you first press AUTO EQ. Each time you press this button, another setting will appear on the display and AUTO EQ will switch to one of the preset settings previously listed. To return to the manual mode (CUSTOM), press the AUTO EQ button until CUSTOM appears on the display. Then you will be able to manually adjust the bass, midrange and treble using the AUDIO button. To find out how to do this, see Setting the Tone following. If your vehicle has the Bose 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 EQ button to scroll through your choices. Select TALK when listening to non-musical material such as news, talk shows, sports broadcasts and books on tape. This settings makes spoken words sound very clear. Select DRIVER to give the driver the best possible sound qualities. Select NORMAL to enhance the stereo effect. Select SPATIAL to make the listening space seem larger. When AUTO EQ NORMAL is displayed, the system will provide the best overall Bose performance. The radio saves separate AUTO EQ settings for each preset and source. 3-36