People have been complaining about the sound in Counter-Strike: Global Offensive for years, and while this doesn't appear to have fixed those issues -- particularly on maps like de_nuke -- it is nice to see that Valve are at least tinkering with it.
According to the post on their official blog and through Steam, the patch predominately focuses on footsteps, the sound models make when landing and the sounds footsteps make when going over a variety of surfaces.
A reason given for the changes was to "reduce repetition and phasing" while enhancing the precision of footsteps in game. Valve has also made footsteps slightly louder in relation to weapon sounds in an apparent attempt to make the position of players easier to identify during firefights.
The full patch notes are below:
SOUND] – Increased fidelity and weight of jump land sound. – Landing sounds now play an additional sound depending on the surface. – 3rd person footsteps are now slightly louder in relation to weapon sounds for increased positional clarity. (Further volume compression may be possible by enabling “sound normalization,” “volume equalization,” or a similar setting in your audio playback device properties) – New surface footstep sounds to reduce repetition and phasing as well as increasing listenability and positional clarity. — Concrete — Wood — Rubber — Snow — Glass — Grass — Mud — Dirt — Solid Metal — Metal Grate — Metal Chainlink – Fixed a bug where give_ammo sound was playing for every shotgun shell insertion animation. – Minor volume mix adjustments – (Note: For players using virtual surround sound, please be sure to set the audio settings in CSGO to 5.1 speakers.) [MISC] – Awp now always un-zooms during reload animation – Misc player animation CPU performance optimizations – Overview icons can now be scaled with the convar mapoverview_icon_scale [STEAM CONTROLLER] – Game now requires Steam Client to be updated as of Oct 14 2015 or later. – Added native support for the Steam Controller [ DEDICATED SERVERS ] – Added concommand sv_setsteamaccount to specify Game Server Login Token. To create a GSLT go to http://steamcommunity.com/dev/managegameservers
The patch hasn't made the vocal quadrant of the CS:GO community particularly happy, but then that's hardly a surprise given the way they tend to react to anything. (Mind you, if Valve could roll out 128 tick servers for matchmaking, that would be a very, very good day indeed.)