Axon 7 sound problem

Hi everyone

I had recived my ZTE axon 7 2 days ago
The music when Gets played with native music app it works & plays smoothly & clearly

But , when gets played with ( music speed changer ) app it ges annoying distortion !!

I had been contact the team for this app looking for solution

My quastion is :

Did any body of you guys has the same problem or only my phone experince this problem?!

Thank you

Sorry for my english:)

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