Robot voice during calls

[#1]

Both before and after the latest update I've been noticing a weird distortion during calls when the other party will sound distorted and "robotic".  It gets so bad I can't understand them but it doesn't happen every time.  At first I dismissed it as simply being a bad signal, but it's happening when I have 4 bars now.  I sound normal to the people on the other end.

Is anyone else getting this?  It seems to mostly happen when I'm using my Bluetooth car kit. 

[Phy]

Boot on safe mode and check if you experience the same issue.

How to boot on safe mode
http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008

How to boot on safe mode on Lolipop
1. press and hold the power key
2. once you get the pop up menu 
3. press and hold "power off" 
4. Boot on safe mode should become available

[#3]

Thanks for the info Phy, I'd been wondering how to get the phone into safe mode so that will be very useful.

Unfortunately it's probably not going to help in this case.  My phone is only doing this occassionally.  I don't make a lot of calls anyway, so I'm maybe encountering this problem every 2 or 3 days.  It usually doesn't happen, so it not happening on safe mode wouldn't really tell us anything, unless I run my phone in safe mode for the next week which would be kind of inconvenient.

However I am reasonbly certain it's not a signal problem as the last couple of times it happened, I made a point of looking at the signal strength indicator.

[Uliwooly]

@Unregistered user

As soon as that happen 

Settings > about phone > status > signal strength > post the results

[#5]

Uliwooly, I'll try to take a screenshot of the signal strength info the next time it happens.

Thanks

[Uliwooly]

Anytime, keep us updated and also check if there are any electronics when that happen 

[#7]

It happened again today.  The signal strength read -81 dBm 16asu.

I have a couple of thoughts.  At the time I was making the call I was also listening to the "Play Music" app, connecting to my car's bluetooth, and getting directions through Waze.  Could it be a processor power or RAM issue?

Also, I have noticed that I only get this when using my car handsfree.  Given that my microphone should be able to "hear" the other side of the call in this setting, could it be a problem caused by the microphone noise cancellation on the M2?

Finally, it is possible that it isn't a problem with my phone at all but rather noise cancellation or signal strength issues with whoever I am calling.  I'd be inclined to dismiss signal strength on the other end since it's only on my side that there seems to be a problem whereas if they had a poor signal I'd sound distorted to them too.

Any thoughts?

[Uliwooly]

@Unregistered user

It'll be better to contact your Local support