You could try lowering the BGM and sound effect levels, while raising the dialogue volume to it's maximum.
Also, what kind of sound set-up and setting are you using? Sometimes if you're using the wrong settings it can affect volume levels, e.g if you're using stereo TV speakers but you're using 5.1 setting on your console, then the dialogue could be coming through very faintly as it's being channelled mainly through non-existent speakers.
If you're using your TV speakers for sound, you could try tweaking the settings and using a pre-set for clear voice, or try enabling/disabling your TV's virtual surround setting.
Personally I've not experienced any voice problem with
L.A. Noire, but for the record I've got it installed to my 360's HDD, I'm using the Digital Stereo setting in the 360's sound settings, have the sound channelled to my TV's speakers and have them set to "movie" with SRS (virtual surround sound) disabled and have the dialogue volume at 10 while the BGM and sound effects are both set to 9.
Cloudwolf616 said:
its not that there hav been reports of it happening on all systems and all my other games and blurays are fine
How are you playing Blurays on your 360? Did you mean DVDs or do you have
L.A. Noire on the PS3 and not 360?