The study investigated the speech adaptations by older adults (OA) with and without age-related hearing loss made to communicate effectively in challenging communicative conditions. Acoustic analyses were carried out on spontaneous speech produced during a problem-solving task (diapix) carried out by talker pairs in different listening conditions. There were 83 talkers of Southern British English. Fifty-seven talkers were OAs aged 65-84, 30 older adults with normal hearing (OANH), and 27 older adults with hearing loss (OAHL) [mean pure tone average (PTA) 0.250-4 kHz: 27.7 dB HL]. Twenty-six talkers were younger adults (YA) aged 18-26 with normal hearing. Participants were recorded while completing the diapix task with a conversational partner (YA of the same sex) when (a) both talkers heard normally (NORM), (b) the partner had a simulated hearing loss, and (c) both talkers heard babble noise. Irrespective of hearing status, there were age-related differences in some acoustic characteristics of YA and OA speech produced in NORM, most likely linked to physiological factors. In challenging conditions, while OANH talkers typically patterned with YA talkers, OAHL talkers made adaptations more consistent with an increase in vocal effort. The study suggests that even mild presbycusis in healthy OAs can affect the speech adaptations made to maintain effective communication.