Dave,
They are correct (probably). Their headset must comply with the law. More likely, regulations, but that's a different subject.
But is that the only issue?
Every employer has a primary duty of care to protect its staff from 'known' risks under the Health and Safety at Work Act. It's common law.
The headset manufacturer doesn't employ the client telephonist.
The employer however, could take issue with the headset manufacturer for not ensuring the user is protected from 'known' risks (like acoustic shock which occurs and causes serious symptoms sub-legal db limitations). But that's like saying the tabaconist should sue the cigarette manufacturer for killing his client!
But then again, perhaps the headset manufacturer doesn't purport to provide anything else other than a sound delivery medium. Your company buys its products base on specification and merit that meets it's needs. If you want protection, then buy a protection device, it's that simple. There are several new devices on the market now that you should look at.
Its a complex issue. We all need to work together, which is what the Acoustic Safety Programme is encouraging.
Sincerely,
David |