Default Z ultra horrible background sounds when calling on tango

I used my z ultra to call a friend from tango. When i use my headphone the sound is really great,
And i don't hear annoying sound on the background. When i takeoff my headphone and place the phone beside my ear, i can clearly hear my friend talking without hearing a weird and annoying sound coming from my zu.
But when i turn on my speaker, i cant nearly hear my friends voice because of this horrible sound coming from my phone.
Its like a sound coming from a police mobile which is soo irritating to the ears. Can anyone confirm if you encounter this kind of problem?
Im running 4.4.2 kitkat. My phone isnt rooted.
Thnx