Replacing the cushion pads on your headset should be a regular occurrence, like changing the oil in your car. Not only does changing the pads have hygienic merit, but it also helps to preserve the original sound intended. Even if the pads are clean, they become compressed as they age, and this alters the effective acoustic space. As a guide, ear cushions should be replaced every 3 months or replaced if the headset is passed on to a new staff member.
