My MacBook Pro's speaker sound is too much low, even mobile phone has louder.What could be issue?,Please guide

I have MacBook Pro 2015 Retina, 13-inch, Early 2015, I have bought second hand. It has too much low audio output I noticed just now.Could you please help me to know what can be possible issue or how can I increase sound.

other MacBook Pro of same model has higher sound than my this MacBook.

please help.

Thankyou.