What audio codecs are available on mediasoup? Which is the best in quality?
I’m using the configuration below, but the audio has echo, a robotic sound
take a look at this one. this might help…nothing to do with codecs
Many are available but you only really want OPUS, it’s quality at low bitrate. The robotic sounds you’re speaking of sounds like server lag, or in some cases someone mess with their audio settings. 
This wouldn’t be media-soup related. Figure it out by running your own tests.