Heat doesn't affect their vocalizations much, but it DOES greatly change their travel patterns.
Hens especially will want to water twice a day if it's dry, hot, and sunny during egg production. Expect them to head to water around 9-10am, sometimes even right off the roost. Look for them to go to water again late afternoon.
Gobblers don't have the same water requirements as laying hens, but they also will hit water, often after the hens have left to lay for the morning (not a factor this late in the season, all mature hens should be setting by now).
One thing that does make a BIG difference is bright sunshine. On days above 75 deg or so with bright overhead sunshine, gobblers especially tend to migrate toward shady areas. Their black feathers heat up more quickly than the lighter colored hens, and therefore feel more comfortable in the shade.
So this time of year, I'd focus on water #1, and shade #2.