Quiet airpods

i recived AirPods first gen for Christmas this year so 3 and a bit months ago. They where both very loud when I first revived them. They are now very quite even on volume 100% I have cleaned both AirPods and case and disconnect and reset them but they still seem half the sound quality the used to be. They have never gotten wet and haven’t been damaged or dropped they live in a protective case. So no damage has come to them. Any help ?