Recently, I start to use the speaker mode when making phone calls. But I got many complaints that my voice sounds muffled: when people on the other end is talking, they cannot hear me at all if I try to say something. It also happens when there is background noise on the other end, they can barely hear me, while I can hear them very clearly. There is no problem if I use handset mode. It's pretty frustrating, I just wonder whether it only occurs on my device or you guys have similar problems.