The authors investigated the impact of loud acoustic stimuli on sensorimotor adaption by having participants move a cursor towards a target and adapting, in some conditions, to a change in feedback. The conclusions were that a loud acoustic stimulus facilitated adaptation to sensory prediction errors and overnight retention of adaptation. The implication is that loud acoustic stimuli might be useful in modulating sensorimotor adaptation and motor learning. This is a very detailed and dense manuscript, and I am left with just a few questions and comments.

1. Why was the LAS intensity so much lower in Exp.2 (80 dBA) than in Exp. 1 (94 dBA)? If an acoustic stimulus needs to be “loud” in order to affect performance, could this significant intensity difference have impacted comparisons across the two studies? Especially given the findings of Furubayashi et al. (2000) that cortical excitability is changed by intensities above 79 dB. If that value is an average, then 80 dB might not be enough to yield a reliable effect. And if 80 dB is as good as 94 dB, then the definition of “loud” should be revised.

2. Another issue with the use of a 94 dB stimulus intensity, especially a 50 ms broadband noise burst with a fast rise time, is that this stimulus will elicit startle responses on most trials early in the session. Since the acoustic stimulus was not presented until after task performance (“upon movement completion”) I do not worry about that startle response affecting the movement, but this reflex elicitation should at least be acknowledged as a possibility. In fact, even the 80 dB stimuli might be expected to elicit startle on many trials (see Blumenthal & Goode, 1991, Psychophysiology). But again, if 80 dB is as good as 94 dB in the current application, the lower intensity might be preferred to avoid both startle and unpleasantness.

3. In Figure 1, the second block is labeled “adaptation.” Is this the same as the “Training block described in the text (p. 5)? Later in that same paragraph the term “adaptation block” is used, and again, is this the “training block”?

4. Look at the denominator of the formula given to calculate percent adaptation.

5. In the Results (p. 7), we are told that “there was strong evidence for the main effect of LAS for the no task error group” “but weak evidence . . . for the standard task group.” These findings are very difficult for me to see in Figure 2. It looks like percent adaptation is usually lower for the LAS condition in the standard task groups and higher for the no task groups, compared to the no-LAS conditions. But these lines are so close to overlaying each other that it is really difficult to see the effect in this Figure. I understand the desire to present the data as a function of Cycles, but perhaps another Figure of the mean across Cycles within each phase would be more informative.

6. In the Implicit Aftereffects paragraph on p. 7, we are referred to “Figure 1 B&F.;” I did not find this designation in the Figure.

7. My final point has to do with memory. The proof that the loud sound increased retention is that “it increased subsequent anterograde interference.” That is, the proof of “memory facilitation” was a decrement in performance on Day 2. Perhaps I misunderstood this point, but is “failure,” that is, increased interference, proof of facilitation of memory by a loud sound? It seems to me that, if this is the case, we might be able to use loud sounds to interfere with future performance, but could we also use them to facilitate future performance? This question of the application of this exact effect is not clear to me.

The authors have done an excellent job of responding to my previous comments. I have a few new comments that I hope will be useful.

In the Data Analysis section for Exp. 1 (page 6), “Analyses were conducted in JASP (Team, 2020)” should be changed to “Analyses were conducted in JASP (JASP Team, 2020)” and the reference citation should be listed as “JASP Team (2020) Version 0.13.1”, not as “Team, J.”

The authors decreased sound intensity in the second experiment to reduce the perceived unpleasantness of the sound, and they suggest that this lowering of sound intensity provides a methodological advantage that does not alter the conclusions that can be drawn from these data. Is it possible to directly compare any part of the data from the two Experiments, to see if sound intensity (94 vs. 80 dB) had a quantifiable impact? If there were any conditions in common across the two studies, a direct comparison of those conditions would go a long way toward the authors’ contention that lower sound intensity is just as good in terms of the adaptation while also being better in terms of participant comfort.

I would like the authors to clarify exactly when adaptation is occurring here. The loud sound was presented after the movement was completed, but it is also stated as occurring “during adaptation of reaching movements.” It is also reported as occurring “during exposure to a sensorimotor perturbation.” Should this be “after” instead of “during?” The authors’ implication is that this adaptation is a process that occurs after, but not during, movement, so adaptation cannot improve performance on the current trial, only on future trials. The authors also mention “re-aiming strategies,” which also would be on the next trial, not on the current trial. That is, with the sound presented after movement termination, re-aiming would not be involved in redirecting movement while it is in process, only in changing movement on subsequent trials. I think that error processing is occurring after movement, when the target is missed, but is there error processing during the movement as well? This is probably just my misunderstanding of what the authors are trying to tell us, but clarification would be helpful.