I have an iPhone 6 and lately it seems as if the volume when I use it as a phone in the normal position seems low. The bar graph seems to indicate full volume. It seems fine when I run it through the systems in my car or truck where it goes through their speakers. I have had to clean lint out of the lightning jack a few different times to get good connection with the lightning cable.
I'm curious if my speaker may be getting plugged with lint or other debris and if so the proper way to clean it out. I have a friend who has the same iPhone and I may try starting a conversation from one iPhone to the other and then switch iPhones to see if the other one sounds louder.
I'm in the habit of placing it next to my left ear. Maybe my hearing has deteriorated a lot but at the present time I would not be able to carry on a conversation with even a modern tractor running unless, I stop and idle back. Listening to music through the headphone jack and headphones seems fine.