The technique and tests herein described were devised to study possible improvement in rating the acoustical excellence of rooms, by using higher pen speeds than had hitherto been available. Recordings of reverberation decay characteristics, made with the new ultra speed technique, are compared with results from older methods of recording reverberation; and it is found that the new method provides a much more adequate diagnosis of recognized acoustical faults.The new technique makes possible ink recording of acoustical levels on a db basis at pen speeds of 5000 to 10,000 db per second, or ten to twenty times that afforded by the high speed level recorder. It uses a new stabilized logarithmic Varistor system for instantaneous conversion to a db basis, followed by a direct writing oscillograph. Hitherto unrecognized requirements for the electronic system are indicated as necessary if adequate stability, linearity, and scale range are to be achieved.