I just found this interesting paper from earlier this year that shows the effects ADHD has on spoken-word processing:

Listen up! ADHD slows spoken-word processing in adverse listening conditions:Evidence from eye movements

From the abstract (formatted for readability):

Background: Cognitive skills such as sustained attention, inhibition and working memory are essential for speech processing, yet are often impaired in people with ADHD. Offline measures have indicated difficulties in speech recognition on multi-talker babble (MTB) background for young adults with ADHD (yaADHD). However, to-date no study has directly tested online speech processing in adverse conditions for yaADHD.

Aims: Gauging the effects of ADHD on segregating the spoken target-word from its sound-sharing competitor, in MTB and working-memory (WM) load.

Methods and procedures: Twenty-four yaADHD and 22 matched controls that differ in sustained attention (SA) but not in WM were asked to follow spoken instructions presented on MTB to touch a named object, while retaining one (low-load) or four (high-load) digit/s for later recall. Their eye fixations were tracked.

Outcomes and results: In the high-load condition, speech processing was less accurate and slowed by 140ms for yaADHD. In the low-load condition, the processing advantage shifted from early perceptual to later cognitive stages. Fixation transitions (hesitations) were inflated for yaADHD.

Conclusions and implications: ADHD slows speech processing in adverse listening conditions and increases hesitation, as speech unfolds in time. These effects, detected only by online eyetracking, relate to attentional difficulties. We suggest online speech processing as a novel purview on ADHD.

WHAT THIS PAPER ADDS?: We suggest speech processing in adverse listening conditions as a novel vantage point on ADHD. Successful speech recognition in noise is essential for performance across daily settings: academic, employment and social interactions. It involves several executive functions, such as inhibition and sustained attention. Impaired performance in these functions is characteristic of ADHD. However, to date there is only scant research on speech processing in ADHD.

The current study is the first to investigate online speech processing as the word unfolds in time using eyetracking for young adults with ADHD (yaADHD). This method uncovered slower speech processing in multi-talker babble noise for yaADHD compared to matched controls. The performance of yaADHD indicated increased hesitation between the spoken word and sound-sharing alternatives (e.g., CANdle-CANdy). These delays and hesitations, on the single word level, could accumulate in continuous speech to significantly impair communication in ADHD, with severe implications on their quality of life and academic success.

Interestingly, whereas yaADHD and controls were matched on WM standardized tests, WM load appears to affect speech processing for yaADHD more than for controls. This suggests that ADHD may lead to inefficient deployment of WM resources that may not be detected when WM is tested alone. Note that these intricate differences could not be detected using traditional offline accuracy measures, further supporting the use of eyetracking in speech tasks.

Finally, communication is vital for active living and wellbeing. We suggest paying attention to speech processing in ADHD in treatment and when considering accessibility and inclusion.