Hi @yesid, sorry to hear about this.
Does this happen during a specific kind of use or in a specific app or does it happen randomly? Have you been able to carry out a quick test of the loudspeaker in the support app to see if the hardware works as intended? To do this, find and tap Settings > Support > Xperia Tests > Speakers & microphones.
Another thing that you can try is to reboot your phone in safe mode to see if you can reproduce this behaviour there. Safe mode is a troubleshooting mode where all apps downloaded from Play Store is temporarily deactivated, that way you can see if this behaviour is caused by a downloaded app or not. For more information on safe mode and how to use it, click here.
If the behaviour persists in safe mode, I would suggest that you try to repair the software using a computer and Xperia Companion. Keep in mind though that a software repair will erase all user data from the phone, so make sure to do a backup of your user data before the repair.
If none of these measures manages to improve the functionality of the loudspeaker, the best thing to do is to get in contact with your local support team in order to have your phone sent to an authorized service center to be examined and possibly repaired. If you have any questions regarding the service such as routines, warranty and consumer laws, these kind of questions are best answered by your local support team as well.
I hope that helped!
