I got my ear speaker loud again by using harsh and thin brush.
- turn off your phone
- open it
- disconnect screen from the phone body
- use vacuum with thin soft nozzle to clean all the dust
- disassemble speaker part and take out sensor and front camera from it's housing
- apply brush from outside intensively.
- you should be able to see the light through the speaker hole
- vacuum speaker hole after cleaning
- you might as well want to clean other parts of your phone. You can do it now. Just be careful.
- assemble everything back
- turn it on and test it. screen should be fully operational, as well as the home button. If something is not right - turn it off again and make sure you have everything connected properly and completely.
- try calling somebody and have them speak to you. Now you can compare loudness of your ear speaker.
Instructions on how to take your phone apart you can find at this website.
Hopefully it will help you solve quiet ear speaker issue. Before applying this method, I had big troubles hearing people on the phone, especially while being in noisy places.