This is on a Dell Inpsiron 9400 with Intel HDA sound (Sigmatel stac9200 chip) Voices are very faint (can not hear them over the fan when volume is at maximum) on all movies with AC3 sound. As a work-around I have created an /etc/asound.conf that has the voice channel(s) coming out of the left side speakers and the background music channel(s) coming out of the right side speakers. Multichannel sound was working properly on this lapop using previous alsa-driver versions (in-kernel 2.6.15??).
At least tell us which drivers and version are you using.
Created attachment 98841 [details] asound.conf for voices on left speakers and background on right Poor hack to be able to get voices and background sounds from AC3 streams. Sound quality is worse than normal.
[I--] [ ~] media-libs/alsa-lib-1.0.13 (0) [I--] [ ] media-plugins/gst-plugins-alsa-0.10.4 (0.10) [I--] [ ~] media-sound/alsa-driver-1.0.13 (0) [I--] [ ~] media-sound/alsa-headers-1.0.13 (0) [I--] [ ] media-sound/alsa-tools-1.0.11 (0.9) [I--] [ ~] media-sound/alsa-utils-1.0.13 (0.9) [I--] [ ~] sys-kernel/gentoo-sources-2.6.18 (2.6.18) uname -r 2.6.18-gentoo
HDA ALSA driver is still incomplete, if you still have problems with latest version of the drivers, please report the issue upstream.