Disable auditing of select statements

Somehow the auditing of select statements was enabled in our oracle database. We have several data processing apps that are generating upwards of 15 GB per day in the audit trail. Now we cannot turn it off because it seems that the noaudit command needs to match the original audit command, which of course no one knows. Does anyone know how to undo this? Can we turn off all auditing and then turn on the usual assortment of audit actions (alter, create, drop, etc.)? We have ran all kinds of noaduit permutations: “noaudit select table by USER;” and “noaudit select any table;” and yet it still posts select statements to the audit trail.