My case with all the notes (6 months worth) has been submitted according to Apple Engineering.
I would suggest anyone with this issue call Apple support, and ask for assistance from senior level support to submit a problem to engineering. Also, submit a feedback request here: http://www.apple.com/feedback
Ask to title your request "Keytone sound during call".
Last, make sure when you call Apple you are ready to run through the diagnostics they will want you to do.
That is:
1. Back up your phone first either through iTunes or iCloud.
2. Restore your Phone.
3. If you are on iOS7, make sure it's the latest version.
-- If you are on iOS6, the last version at this time is iOS 6.1.4
4. Be prepared to do that either prior to the call or during.
5. Ask for your case to be submitted to Engineering and to have a call back to resolve.
Hopefully if we all band together, they will find the issue and we can get our hearing back after the numbing keytone has been blasted in our ears enough times.
Please share your expierences here, but also note that other threads exist on this forum as well for the exact same problem!!
And many more!
... And on almost ALL the carrier forums for support as well. If we all ask for help, and not just complain here, we should get a meaningful response and hopefully a fix! Post up here when your case is in with Apple support.