minecraft alpha has no sound unless i type-Dhttp.proxyHost=betacraft.uk -Djava.util.Arrays.useLegacyMergeSort=true in the arguments of the version

Put the summary of the bug you're having here

What I expected to happen was...:
sound

What actually happened was...:
no sound and skin is default

Steps to Reproduce:
1. create alpha
2. load alpa
3. no sound