According to my experience, a sound coming from just one source will sound and feel louder than a sound coming from all directions, with equal spl. Allow me to elaborate. On my smartphone I have a spl meter (because I'm a classical musician and I value my hearing). Let's say that a speaker is creating a sound of 83 decibels. This is roughly the spl of an aircraft cabin. In an airplane cabin, I can talk in a normal conversational tone to other people. However, when I'm in a room with the speaker, I have to raise my voice. Why is this? Sorry, I know it sounds like a stupid question, but this has been on my mind for quite some time, and I'd like to know the answer.