Project Reality Forums

Why do some voices sound metallic/robotic?

Mumble is optimized for low latency so when your connection has a lot of variance ping wise some audio packets will arrive to late for mumble to consider them. A bad connection might even lose packets completely. If that happens the codec tries to "cover up" the fact it misses data. Before version 1.2.1 our new codec CELT was not as good at this as Speex (the old codec) so make sure you use a recent version. Mumble also has a so-called "jitter buffer" that tries to counteract the ping variance issues but it is not perfect, we are currently collecting usage data to improve it.

You can usually reduce the artifacts by increasing buffer sizes, but a (ping wise) stable connection is the best solution. Be aware that the ping has to be stable from the sender to the server and back to the receiving end.

The issues mentioned before are the most common ones. Some people might hear metallic sounding voices even with a stable ping on both ends. This might be a result of noise filtering by Mumble. If the environment of the sender is especially noisy, some parts of the voice will be filtered as well. The alternative would be noisy sound, meaning precious bandwidth would be used to encode noise and the clarity of the voice would also decrease.