Just tried it on my S5. If I put my ear to the speaker with my iphone right sat next to the s5, I can just about hear a faint hiss. This is whether or not music is playing (ie playing, but with vol at nothing). The hiss is so quiet though that even a couple of inches from the speaker I can no longer hear it (though whether you have more sensitive hearing or not, I 'm not sure). I really wouldn't be able to hear it under normal circumstances, so if you can, then it's definitely different to mine.