An investigation of the transmission of suprasegmental features of speech using the multipoint electrotactile speech aid (MESA)

Previous investigations of the speech transmission capabilities of the MESA have shown that trained subjects can correctly perceive certain segmental features of speech when they are spoken in isolation. The present study was conducted in order to evaluate the perception of one of the components of sentential rhythm—syllable number. Sentence stimuli of one, three, five, and seven syllables in length were videotaped. Five normal‐hearing adults were required to “tap out” the rhythm of the sentences on a Morse code key under three receptive conditions: (1) visual alone—lipreading, (2) tactile alone, and (3) tactile plus visual. When scored for the absolute number of correct syllables, the results demonstrate significant differences for the main effects of modality and for the length of utterance. Further analysis will examine the degree and direction of error for each modality and for length of utterance. A replication of this experiment is underway in which a limited frequency range on the MESA is delivered to the subject. Implications for the design of sensory aids which optimize the reception of suprasegmental features of speech will be discussed.