The development of simple automatic diagnostic and assessment procedures for the comparison and optimisation of TBS-based DVI systems is presented. The use of a "Diagnostic Matrix" [1] to assess the variability of input acoustic events purporting to be the same word and to indicate the degree of orthogonality between the acoustic events which form the vocabulary under examination, is discussed. The process of adapting the diagnostic procedures, so that system performance may be evaluated against incremental system parameter changes is described. An initial set of "Assessment procedures" used to predict likely system performance under varying noise conditions is presented. Experimental evidence is offered to support the discussion.