Acoustic parameters were measured for vowels spoken in /hVd/ context by three postlingually deafened cochlear implant recipients. Two female subjects became deaf in adulthood; the male subject, in childhood. Recordings were made before and at intervals following processor activation. The measured parameters included formant frequencies,F0, SPL, duration, and amplitude difference between the first two harmonic peaks in the log magnitude spectrum (H1–H2). A number of changes were observed from pre‐ to post‐implant, with intersubject differences. The male subject showed changes inF1, vowel durations, andF0. These changes were consistent with one another; however, they were not necessarily in the direction of normalcy. On the other hand, the female subjects showed changes inF2, vowel durations,F0, and SPL, which were in the direction of normal values and, for some parameters, tended to enhance phonemic contrasts. For all three subjects, H1–H2 changed in a direction that was consistent with previously made flow measurements. [Work supported by NIH.]