When I make a phone call, people on the other tell me that my sound is like I am speaking in a huge water pot or something like a pot.
I have a Samsung Galaxy S3.
Check the microphone of the device. On the S3 I believe it is the little hole on the right side of the charging port. I have seen this issue numerous times and on occasion, it's a clogged or semi clogged mic port. If the issue is intermittent, the aforementioned possibility is less likely. Other times it is network related, app related or, worst case, a failing microphone.
I've had this problem with my own S3. Usually, it happens when I'm holding the phone angled away from my head. In my case, holding the phone flat against the side of my head helps. I'm not sure if it's some sort of background noise cancellation gone wonky or what, but that little shift in position is all it takes for me.
It could be any or all of the following:
Speaker's volume is too low if you have a protective case around your S3. Otterbox cases, and a few others, have been known to cause problem with the S3's speaker.
To be fair though, speakers on Samsung devices are notoriously bad when it comes to receving and transmitting sound.
Some Android firmware installed on the S3 can cause the audio software to lower the volume unnecessarily. Try upgrading your S3 to the latest Android firmware, like Jellybean, KitKat or later.