I used to when i worked for my uncles firm, however since setting up my own, i haven;t bothered - i think i will get it back thou!
I only use one ear phone anyway - and before you say anything its not against any H&S regs as far as im aware as many warehouses (such as Argos) use voice operated check systems and you have a earphone with that for that working in and around large main risers, forklifts etc.