You're missing out on an amazing gaming experience if you haven't already downloaded Strelok's sound overhaul for Half-Life 2. This release is a minor update for said sound overhaul that fixes some incorrect directories, unintentional omissions, out-of-sync reload sounds, and a sonic boom sound that was too soft in Strelok's original pack. Additionally, it adds a few new sounds, like the high quality heart beat and breathing sounds from Strelok's fifth Half-Life: Source improvements pack and all of Valve's formerly reversed zombie sounds now un-reversed. If you find any errors in Strelok's sound overhaul that I missed (except for the omitted drip loop sound in ambient>water), let me know and I will fix them as soon as possible.
UPDATE 5/20/2012: I added two new sounds that replace the MP7's fire-burst sound and the HEV suit's neurotoxin warning (it now notifies Gordon that it administered an antidote). The neurotoxin warning sound came from one of Strelok's HL:S improvements packs. I also added new scripts to make the Combine snipers say the correct "Grenade!" lines, to make the rebel turrets from Episode 2 use a cooler explosion sound, and to reactivate an unused zombine growling sound. Use the optional scripts if you want more realistic helicopters and quieter turrets.