Are they in the same room? You could try a noise machine to muffle some of the noise? Eventually they may just get used to it? Both my kids have noise machines so they don't wake each other up if one is crying. The older one can scream his little head off at times and it doesn't wake up the little one. Their door's to their separate rooms are closed. I start my first 12 month old next week so we will see how my 10 month old and her will do at nap times!!!