1. Check whether the music file itself is mono (only the left channel) or the left channel is damaged. Try to re-download or use other music files.
2. Check the settings of the music file in PPT, select the music file, click the "Format" tab, select "Audio Options" in "Audio Tools", open the "Stereo Settings" option, and change " Channels" is set to "Stereo".
3. Adjust the sound settings in PPT, select the music file, click the "Playback" tab, select "Channel Settings" in the "Volume" drop-down menu, and set "Channel" to "Stereo" ".
4. Adjust the sound settings in the computer system settings, open the "Sound" option in the "Control Panel" or "Settings", find the audio settings, and set the "Channel" to "Stereo".