In a country that allows cell phone use on planes, or with VoIP using satellite Internet, how feasible is it to use a phone by the normal method of holding it to your face on a small GA plane such as a Cessna 172? Is it too loud?
I've made a call 3 times from a light GA aircraft. 2 of those were on the ground with the engine running - once using a noise cancelling bluetooth headset and the other holding the phone to my ear. The time the phone was held to my ear it was very hard to hear the other end and they were very aware that I was in a very noisy environment. The time using my headset the callee was completely unaware that I was in the aircraft and I could hear them clerarly.
That probably says a lot about a decent directional microphone and decent noise cancelling - but I'd say that anecdotally with very little data the answer to your question is that it is indeed too loud to realistically use a phone in the normal way in a light GA aircraft such as a C172.