If you are facing low bass in your sound you can follow these steps: 

a) Ensure if user is listening downloaded song/Online APP song or Youtube Song. Note- Youtube songs quality may be lower than the Online APP or downloaded song quality

b) Listen the same song through different mobile phone

c) Use different Music Player

Tip: An equalizer (also called an "EQ") is an audio filter that isolates certain frequencies and either boosts them, lowers them, or leaves them unchanged. Equalizers are found on a wide array of mobile devices.

An equalizer will adjust audio output so that certain frequencies are emphasized over others.

Recommend customer to try a different equalizer setting. If this doesn't work, proceed with the next step

 d) Check Streaming quality