Default [Q] [Help] Audio Frequency response of LG G2

Hello:

I was testing my LG G2. I generated some high frequencies tones audio files in my PC but when I playback on my phone I don't get a clean tone. Its like a mixtures of tones with lower freqs and a higer in the middle. Could anybody try it?

While I try to upload the files I've generated, there are some wave generators or tone generators in play store.

Edit: I'm on bruce2728-d80220f rom