[1.7.2] Unable to play unknown soundEvent

On OSX, I've noticed that when running I hear no sounds, but see lots of messages on the console like this:

[22:57:55] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:mob.cow.say

[22:57:55] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:mob.spider.say

[22:57:55] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:mob.spider.step

[22:57:55] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:mob.cow.step

[22:57:56] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:mob.spider.step

I'd like to understand how to fix this.

That's easy. You have assets in wrong place. Copy folder 'assets' to folder where you can see folders like 'save', 'config', 'mods', etc.

'Assets' folder must be in 'eclipse' folder for default.

I'm puzzled, because the contents of forge-1.7.2-10.12.0.985-src/eclipse/assets is:

find sounds/mob/spider

sounds/mob/spider

sounds/mob/spider/death.ogg

sounds/mob/spider/say1.ogg

sounds/mob/spider/say2.ogg

sounds/mob/spider/say3.ogg

sounds/mob/spider/say4.ogg

sounds/mob/spider/step1.ogg

sounds/mob/spider/step2.ogg

sounds/mob/spider/step3.ogg

sounds/mob/spider/step4.ogg

What am I missing?

I can advise you to update forge. I found how to fix assets don't work. These instructions for you if you use eclipse

 

Create new folder anywhere, extract forge src to this folder, and run gradlew.bat with command setupDevWorkspace (create bat file with string "gradlew.bat setupDevWorkspace" and launch it), then run gradlew.bat with command eclipse (bat with "gradlew.bat eclipse"). After all  start Eclipse and make folder "Your-Forge-Src-Folder/eclipse" eclipse workspace. The End. =)

I can advise you to update forge. I found how to fix assets don't work. These instructions for you if you use eclipse

 

Create new folder anywhere, extract forge src to this folder, and run gradlew.bat with command setupDevWorkspace (create bat file with string "gradlew.bat setupDevWorkspace" and launch it), then run gradlew.bat with command eclipse (bat with "gradlew.bat eclipse"). After all  start Eclipse and make folder "Your-Forge-Src-Folder/eclipse" eclipse workspace. The End. =)

Indeed. So simple. I was importing the project into a separate workspace. That was the cause of my sound problems.