Incoming call maybe? Does it happen every call? Has it always happened or did this just start? Apple may be able to troubleshoot the issue.
No, nothing incoming. It's my husbands phone, it happens every call, except when he called me to test the chirp. I too have an iPhone (an old one). I'm not sure what the problem is but it's driving him crazy. He is planning to take the phone into Verizon today. Thanks for taking the time to respond.
I purchased an iphone 6 at the end of March and I have been experiencing the same problem with chirps. The chirps sound similar to microphone type feedback coming from the person you are talking to which build up to sudden very loud short chirps that feel like they damage your ear when it occurs. Not an enjoyable experience especially after a dozen or so of them in a row. Ouch.
I read elsewhere the chirp issue may be related to other apps running in the background but every time it issue occurs I carefully close any apps I am aware of, and it does not seem to cure the problem.
I haven't experienced this at all so I can't begin to imagine what it is. Has anyone with this problem contacted Apple Support to see what this could be?