Pontiac 2003 Aztek Owner's Manual page 432

To turn the vehicle's speakers on and off, press either
the CD/AUX or the TAPE/CD button on the front
audio system. The audio from the entertainment system
can be heard through both the wireless headphones
and the vehicle's speakers at the same time.
You can listen to the entertainment system through the
wired headphone jacks on the RSA system (if equipped)
when the following occurs:
The RSA system is on,
a DVD or auxiliary device is playing, and
The volume on the audio system may vary when
switching between a radio station, CD, DVD, cassette
or auxiliary device.
If there is a decreased audio signal during CD or DVD
play, you may hear a low "hissing" noise through
the speakers and/or headphones. If the hissing sound
in the wireless headphones seems excessive, make
sure that the headphone batteries are fully charged.
Some amount of hissing is normal.
RSE is displayed on the front audio system by
pressing the TAPE/CD button on the RSA system.
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