Within minecraft 1.4.5 (and too my understanding 1.4.4 downloading the update (1.4.5) will not download the full "Resources" file, meaning that the only sound file you get is "sound3" which contains "ambient", "cave", cave1.ogg and cave10.ogg. This is affecting the entire games sounds.
Related issues
duplicates
Comments
CubeTheThird
fuj1n
This is because all the resources nowadays download as you play, which means that you have to keep playing, and eventually all the sounds will be downloaded, even sound3 is not downloaded during the update process.
For technical support, please visit this website. It is likely your firewall is blocking part of the download.