You may be looking for phonic disruptors used by the Bane.

Sonic disruptors were Martian weaponry. On Peladon, all sonic weaponry, including disruptors, were banned from the Martian refugee camp.

At the refugee camp, Sslurn had accidentally killed a Martian mother with a disruptor while he was kidnapping her child.

While Lord Axlaar was fighting Grun, Sslurn killed Grun with his sonic disruptor.

When he was knocked backwards after being stricken by the Third Doctor, Axlaar accidentally killed Sslurn with his disruptor. (AUDIO: The Prisoner of Peladon)