The volume and the pitch seem to be ignored in the new packet (https://wiki.vg/Pre-release_protocol#Entity_Sound_Effect) used to play a sound at an entity.
After some simple investigation, it seems like the bug should be easily fixed.
The names are from http://export.mcpbot.bspk.rs/
If we look at the following method, we can see that there is two parameters not being used (volume and pitch, indeed) while there is a constructor for EntityTickableSound that take them
net.minecraft.client.world.ClientWorld (the method called in the packet handler of "SSpawnMovingSoundEffectPacket")