I have the Realtek High Def onboard soundcard. I have the latest drivers (and have tried earlier drivers) and find if I have full sound acceleration I get loud, full volume screeching and buzzing noises when there is a lot of gunfire and/or explosions. If I turn the sound acceleration down to one above no sound acceleration I don;t get the buzzing, etc, but then some of the voice conversations drop off, so I will click a conversation option and get a vocal response, but then on the next option the NPC's lips move but no sound comes out! Also some game effect sounds drop out, like gun firing or reloading sound effects.

This means I only have one bad choice. I can play without the screeching noises in battles, but not have full speech or sound effects, or I can have full effects but get screeching noises when a battle ensues! Nice choice, eh! Who would have thought in a late 2010 game you would be having to turn down sound acceleration! This what I have to do 10+ year old retro PC titles!

On the web I have seen answers to various sound issues that say to turn off sound acceleration altogether, or set the soundcard to 2.1, but they don't tell you about the voice or effect drop out when you do that!

I only have this problem with Fallout New Vegas, not with Fallout 3 or Oblivion. I also have no problems with sound on any of my other games like GTA IV or Mass Effect or Bioshock, etc!

I think this is a Bethesda/Obsidian not a Realtek issue, and that Bethesda/Obsidian should be talking to Realtek, because unlike graphic cards, when people always say what card they have, with sound issues few say what card, and I believe the majority of people that have sound problems are like me - using a Realtek card!

Yes, you could be right with the connection between Bethesda & Realtek and maybe in the next patch for this game the issue might be resolved. But in the meantime, may I suggest (if your budget can allow) that you invest in a dedicated sound card for your gaming PC? especially one that has its own memory built onto the card. I have used such cards for years now and once I decided to see what it would be like using the onboard sound chip... That was a big mistake!... after using dedicated sound cards for long time now, I would never go back to built in audio chips for 5.1 surround sound . The difference is quite staggering in terms of shear audio quality and realism, not too mention less work for your CPU to do in the back ground and a little more ram freed up for the rest of your system depending on the card you get.
On board sound has come a long way since the days of AC97 audio was introduced back in the 90's but it still has'nt caught up to dedicated sound cards.

Thanks for responding. If it was a general problem I would save up for a soundcard, but when the problems are only with one game, thre is no way I am going to spend money when it's the games fault I had to spend it!

Given in the last month I have played GTA IV, Fallout 3, Gothic 2, STALKER Call of Pripyat, X-Com UFO Defense and Starcraft, amongst others, all running in XP with no sound issues at all, I am not a happy camper that one game, Fallout New Vegas has such horrendous sound issues! When I said loud buzzing, I mean the sound comes out at the loudest volume the soundcard/speakers can put out - meaning it's very jarring indeed! It is NOT the same volume as I have the game set at!

So once again, thanks for your suggestions, but I will forgo spending $80 just to get one $60 game working. If need be i'll sell the game and wait for the Game of the Year Edition, hwich will save me enough money that getting a soundcard, if still needed, wouldn't be so bad!

I've got the same onboard soundcard and experience pretty much the same sound issues. Also with mine it's as if it's not keeping up with the sounds in the game. I've taken to opening the console just so all the sounds can 'catch up.' That means they then all play at the same time, everything that wasn't playing 10 seconds earlier - gunfire, sound effects, NPC pvssyr, etc. It mostly happens when there's a lot of activity in the one place.
I'll look at getting a proper soundcard later on.

As I said, its like I am playing a retro PC title with all the 'turning down acceleration' stuff! If Oblivion can play with no sound issues at full sound acceleration on my system, and if Fallout 3 can sound fine at full sound acceleration on my system, then I don't know why New Vegas want me to have sound acceleration turned off so it can play the loud gun and explosion sounds during battle and then want the acceleration turned back up to play the voice overs!

I had this problem with Fallout 3 and had it just now in New Vegas with my Asus Xonar.

I did a few things at the same time so I'm not 100% certain what fixed it for me but I believe it was setting bEnableEnviroEffectsOnPC=0. If enviro calculations are being done live then that would explain the fix.

The other changes I made were:

iMaxImpactSoundCount=128iMaxSizeForCachedSound=1024iAudioCacheSize=65536

In the past this audio prob never benefited from changing those numbers so I'm not sure if they helped at all this time. I can guess it doesn't render the environmental effects onto the sounds before it caches them so maybe this is just a mem cache for audio files.

Thanks for all this. bEnableEffectsOnPC=0 was already set, but the others weren't. Will give it a try - what is there to lose!

There's also this variable in the Fallout_default.ini:
fMaxFootstepDistance=1100.0000 (or 11000.0000) as default value.
I lowered mine to fMaxFootstepDistance=400.0000 getting rid of the delay in the sound playing I was having, same issue as Mystykstar. The only ingame differences is that you won't hear footsteps as far from before.

I tried your settings and still have to turn the sound acceleration down to one bar from the far left. This is what solved the buzzing too, So I cannot tell you if the buzzing has been fixed until I can play the game at full sound acceleration like I can Morrowind, Oblivion and Fallout 3!

@glsix, couldn't reply normally as there was an error(!) I will try your option and see if it changes anything. Thanks for being willing to help!