Is SteelSeries Sonar busted or just a cheater?

I was playing a ranked game when my Omen got into a 1v1. He smoked an area off and walked around, while a teammate commed that the enemy sage made a footstep into the smoke. Omen switches to a judge and kills the sage in the smoke. Now, the teammate claims that he uses SteelSeries Sonar and could hear a step, but I clipped it and could hear no footsteps at all; they were nonexistent. Is SteelSeries really that broken that you can hear what others cannot, or was he cheating? This player was also a smurf in low diamond who had another account in high immo with 20 straight wins with MVP and 40/10 K/Ds each game. What do you guys think? Could he just have been walling?

cheating

Cheating