Galaxy J7 (2016), Android 7.1, Earphone's voice level becomes low day by day?

[Android Central Question]

As per step 1, from a week, found earphone's volume becomes low and proper. Without earphone Galaxy J7 2016' sound is well as compare with earphone, i searched answer on this community. According to this i used bud and cleared sound piece but it remains unchanged. Externally i don't found any problem with earphone. Whats are the problem, pls tell me.