iPhone X ear speaker quiet during calls

My iPhone X is 25 months old I think because my contract has just finished, somewhere after the first few month it got quiet. During calls I can hardly hear what people are saying, if im on the streets I often can't hear what people are saying at all but indoors its tolerable, but im always pressing the volume up button to make sure its as loud as it can be.

Ive tried to fix the low ear volume by following suggestions on Google and Youtube, changing Setting like disable noise cancelling, turn bluetooth on and off etc, etc.

The only fix ive not tried properly yet is a clean IOS install because when I did try it in IOS12 at the start of the setup I entered my Apple ID which automatically entered my setting and connected my bluetooth earphone settings, apparently there can be an issue with some 3rd party BT devices which effects the ear speaker volume. Ive not tried a clean install again because I worry that if I setup under a new ID then ill have trouble finding my Apple ID backup in IOS13.2 and OS X 10.15.1 as it has no specific backups with date like we did in iTunes, or perhaps I dont know of them yet. If I loose all my contacts and photo's ill be gutted, plus all the app hassle.

The local computer service shop says leave the iPhone for 2 hours and he will replace the speaker but ive done that with my iPhone8 and the front screen never fitted back together perfectly, so id rather avoid a service if poss.

QUESTION: Does anyone have any suggestions for testing the quality of the ear speaker, maybe an app can play sound through it or something? if that came through quiet then id know it was a bust ear speaker.

Any suggestions would be appreciated.

Thanks

ant...