SwitchingVocalisation is a vocalisation that signals a immediate
speaker transition; that is, a transition from speaker to
speaker (as opposed to speaker to Grp or speaker to Pause).
E.g (speakers A, B, C):
AAAAAAAABBBBBBBCCCCCBBBBBPauseBBBBSwitchingPauseAAAAAGrp
^ ^ ^ ^ ^ ^
| | | | | |
| | | ----------- Non-SwitchingVocalisation
| | |
---------------------> SwitchingVocalisation