Effect of a Competing Message on Synthetic Sentence Identification

The function relating performance to intensity for synthetic sentence message sets presented in quiet is exceedingly steep. Two experiments were conducted to determine the degree to which the performance-intensity (P-I) function could be flattened by adding a competing message at selected message-competition ratios. Data were obtained from five trained listeners in a criterion-controlled experiment and 23 naive listeners in a criterion-free experiment. Addition of the competing message flattened the P-I function substantially. The degree of flattening was related to the presentation level of the messages.