Background: Microswitches can be vital tools to help individuals with extensive multiple disabilities acquire control of environmental stimulation. This study was aimed at extending the evaluation of a computer system used as a microswitch for word utterances with three participants with multiple disabilities. Method: Sets of 7 or 12 word utterances were used for the participants. The utterances were divided into three groups, which were exposed to intervention successively. During the intervention and a 2-month post-intervention check, the participants' emission of the target utterances led the system to present favourite, matching stimuli (i.e. provided that it recognized the utterances). Results: Intervention data showed that (1) the participants increased the frequencies of the target utterances and (2) the computer system recognized approximately 80% of those utterances. These findings were maintained at the post-intervention check. An analysis of the levels of occurrence of individual utterances showed statistically significant differences among them, in line with the notions of preference and choice. Conclusions: The computer system was useful as a microswitch to enable access to favourite stimuli. There is a need to improve the accuracy of the system with respect to its recognition of the participants' utterances.