I seem to have the same problem as this guy
I recently bought a Thinkpad T420 and each time I start up the game, there is no sound. It seems to be a problem with the Conexant 20672 SmartAudio HD sound card. Both the Thinkpad T420 and Thinkpad X220 share this same part.
The game turns off all the sound on my computer even when I alt-tab. It isn't fixed until I exit the game, than sound returns to my laptop.
Could I see a screen shot of the sound settings config in HoN?
Get the latest drivers for your Soundcard and it should work fine as stated by the guy from the other thread.
ps.: Post the screenshot for Root if the driver update does not solve your problem.
Follow the Wiki & remember console.log
WINXP: C:\Documents and Settings\[user]\My Documents\Heroes of Newerth\game\
WIN7: C:\Users\[user]\Documents\Heroes of Newerth\game\
MAC: /Users/[user]/Library/Application Support/Heroes of Newerth/game/
LINUX: ~/.Heroes\ of\ Newerth/game/
Need Live help? irc://irc.s2games.com/#techsupport