Iphone 4 speaker problem/high pitched sound

[applemessiah]

I have an iphone 4 that i am working on. Motherboard is from another phone. I installed it and it powers up and everything. I decided to test out speakers and very very low sound comes out with lots of static and also a high frequency/pitch sound. I switched out the charging port/speaker and problem persists. I also tried making a phone call and can barely hear the person thru the earpiece speaker....what could be the problem? Motherboard works fine in the other phone. any suggestions appreciated.