WHERE I CAN FOUND ATI FUNCTION DRIVER FOR HIGH DEFINITION AUDIO ATI AA01 5.18.0.5507 FREE DOWNLOAD

if your computer came with a motherboard disc the sound drivers could be on it
click start control panel administrive tools computer management device manager scroll to sound video and game controllers you might see a yellow question exclamation mark? ! or a red X Right click to reinstall drivers if you don't have a disk with the sound drivers you have to download them
http://download.cnet.com/g02-cd33-a3-rar/3000-2098_4-200366.html

ATI MOBILITY RADEON XPRESS 200

ATI Function Driver for High Definition Audio - ATI 793C

ATI Function Driver for High Definition Audio - ATI 791A

ATI Function Driver for High Definition Audio - ATI AA01

ATI Function Driver for High Definition Audio - ATI AA11

ATI Function Driver for High Definition Audio - ATI AA09

ATI Function Driver for High Definition Audio - ATI AA19

this driver package is 480 mb

http://download.cnet.com/g02-cd35-a1-rar/3000-2098_4-200883.html
this one is much the same
if these arent right you will find free sound drivers
http://download.cnet.com/2000-20_4.html
on the home page you should see a search tab just type in what you are looking for
(be precise)but don't use numbers or / - also the download software finder under that there will be a list place a tick in the box of any one you want/need
hope it helps

below you will find the proper download to correct this issue.

http://xpdrivers.com/ati/_2_135301.cfm?gclid=COa_zZyH1qYCFY64KgodFWbxHwxp/ati/sb600chipset

You haven't mentioned your PC Operating System ? here are few links to download the Audio Codec Drivers for your PC

Vista O/S
http://download.cnet.com/SigmaTel-High-Definition-Audio-CODEC/3000-2110_4-173629.html

XP
http://thydzik.com/sigmatel-high-definition-audio-codec-driver-for-windows-xp/

Win 7 ( from this link you find all drivers for All O/S )
http://www.radarsync.com/drivers/d172416-sigmatel_high_definition_audio_codec

This model of Presario has an audio controller that supports the high definition audio. You need to have Microsoft Universal Audio Architecture (UAA) Bus Driver for High Definition Audio installed on the computer before installing the audio driver. Here is the link for the Microsoft Universal Audio Architecture driver that needs to be installed before installing the audio driver: ftp://ftp.hp.com/pub/softpaq/sp33501-34000/sp33867.exe
After the installation of above drivers install the following drivers
Conexant CX20549-12 High Definition Audio driver:
ftp://ftp.hp.com/pub/softpaq/sp36001-36500/sp36090.exe

http://support.amd.com/us/gpudownload/windows/Legacy/Pages/integrated_mce-xp.aspx?type=2.7&product=2.7.5.3.3&lang=English

http://support.euro.dell.com/support/downloads/download.aspx?c=tr&l=tr&s=gen&releaseid=R129514&SystemID=PLX_PNT_320&servicetag=&os=WW1&osl=EN&deviceid=8639&devlib=0&typecnt=0&vercnt=1&catid=-1&impid=-1&formatcnt=1&libid=3&fileid=172546   for applitacion
http://support.euro.dell.com/support/downloads/download.aspx?c=tr&l=tr&s=gen&releaseid=R129514&SystemID=PLX_PNT_320&servicetag=&os=WW1&osl=EN&deviceid=8639&devlib=0&typecnt=0&vercnt=1&catid=-1&impid=-1&formatcnt=1&libid=3&fileid=172546  for driver.
thanks for choosing FixYa.

i think *********** bord is support 64 bit so u ave to download hot fix from here
http://drivers.softpedia.com/progDownload/ATI-Catalyst-Bioshock-Hotfix-8401-Vista-32-64bit-Download-40003.html

In my lenovo sunrise the driver for the sound card is Conexant High Definition Audio Venice 5045 and works fine.

it seems as if you need to select your appiorate sound device
you can do this by clicking start / all programs / accessories / entertainment / volume control
then click on options and then properties , in the MIXER DEVICE select the appiorate sound device. is you are not sure whic one, play around until you find it. Also verify your settings for your ATI hight defionation audio to ensure you got it set up properly

download:
http://download.windowsupdate.com/msdownload/update/software/svpk/2008/04/windowsxp-kb936929-sp3-x86-enu_c81472f7eeea2eca421e116cd4c03e2300ebfde4.exe