A is tried for riot and is proved to have marched at the head of a mob. Under BSA section 7’s…

Section 7 illustration (f) expressly treats the mob's cries as relevant as explaining the nature of the transaction, so "They are relevant as explaining the nature of the transaction" and not "They are irrelevant", "They are relevant but cannot explain the nature of the transaction" or "They must be excluded as hearsay even when offered to explain the transaction". Their relevance for that purpose does not depend on proving the truth of every assertion shouted by the mob.