"netcode is written in a completely different" way than in Street Fighter IV.
Basically they're experiencing some teething trouble with it. Four-player matches exchange "a lot more than the normal" data than 1v1 battles, notes Capcom. Looking into it.
It's a fine balancing act as some things were traded off to secure a smooth online experience - it appears sound was a casualty. The team are investigating what they can do.
"The new netcode implemented in Street Fighter X Tekken allows for up to four players to have a smooth online experience, however depending on the connection stability between players, things like 'spontaneous match rollback,' 'voice effects cutting out,' and 'sound effects cutting out' also are occurring," said Capcom's Tomoaki Ayano.
"This netcode is written in a completely different way than the Street Fighter 4 series netcode, and that is why these problems are occurring." Sound abruptly cuts during online battles which understandably is annoying.
"As Street Fighter X Tekken is a tag battle game, the amount of data that is exchanged between player connections is a lot more than the normal 1v1 battles of the Street Fighter IV series. In order to compensate for this and provide a smooth gameplay experience, the netcode was written the way it currently is. Unfortunately, this has also brought on the sound problems we are having now," continued the assistant producer.
"In order to completely fix all the sound issues, the smoothness of the online gameplay has to be traded off, so it is a very complicated and difficult balancing act. We would like everyone to know that the development team is currently looking at various ways to improve the sound issues."
An update is promised soon. "Thank you all for your understanding," said Ayano-san.
Rumblings from some fans claim it isn't playable at all online. Street Fighter x Tekken releases March 6th in the US and today in Europe for Xbox 360 and PS3. Both platforms are affected by the netcode hiccups.