sound volume issue

Alsa-base 1.0.13-3ubuntu1

When I use the buttons on m laptop to increase volume, plays very high at when it reachs the middle of the bar (or 50%) and goes much lower again.

when I play the quake 4 demo, sound is very noisy, and I have to turn it off.

lscpi:
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 02)

lsmod|grep snd
snd_hda_intel 21144 1
snd_hda_codec 164224 1 snd_hda_intel
snd_pcm_oss 44416 0
snd_mixer_oss 17408 1 snd_pcm_oss
snd_pcm 79236 3 snd_hda_intel,snd_hda_codec,snd_pcm_oss
snd_seq_dummy 4740 0
snd_seq_oss 32896 0
snd_seq_midi 9600 0
snd_rawmidi 25216 1 snd_seq_midi
snd_seq_midi_event 8448 2 snd_seq_oss,snd_seq_midi
snd_seq 52464 6 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq_midi_event
snd_timer 23428 2 snd_pcm,snd_seq
snd_seq_device 9100 5 snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_rawmidi,snd_seq
snd 54020 12 snd_hda_intel,snd_hda_codec,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_seq_oss,snd_rawmidi,snd_seq,snd_timer,snd_seq_device
soundcore 8672 1 snd
snd_page_alloc 10888 2 snd_hda_intel,snd_pcm