Hi @Alias441, let me see if I can help out here!
Which speaker on the phone are you referring to, the ear speaker or the loudspeaker? Also, have you been able to carry out a quick test of the speakers to see if the hardware works as intended? To do this, Find and tap Settings > Support > Xperia Tests > Microphone and speakers.
Another thing that you can try is to reboot the phone in safe mode to see if this behaviour persists there. All apps downloaded from Play Store is temporarily deactivated while in safe mode and by doing this, you can see if this behaviour is caused by a downloaded app. For more information on safe mode and how to use it, click here.
If the behaviour of the speakers persists in safe mode,I suggest that you try to perform a software repair using Xperia Companion and a computer. Just make sure that you have made a backup before performing the repair since the repair will erase all user data.
If none of these measures manages to improve the quality of the speakers, I am afraid that the only thing left 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.
Try these measures and let me know how it goes!
