Hearing protection is vital for many people in a wide range of industries around the world. In fact, in many situations it is critical in protecting an individual’s hearing. Worldwide, approximately 900 million people suffer with some form of hearing loss. Many of these cases could have been prevented with the correct use of adequate hearing protection.

Most industrialised nations have some form of occupational noise legislation. For instance, in the UK the ‘Control of Noise at Work Regulations’, based on a European directive, provides minimum health and safety requirements. These regulations set out the action values and exposure limit values at which employers must act. At a daily or weekly exposure level of 80dB(A)/135dB(C) peak or more, the employer must provide information and training to staff and make hearing protection devices available. At 85dB(A)/137dB(C)peak and above, the employer must take reasonable action to try to reduce the noise in the workplace by using engineering controls or administrative methods. If the noise cannot be reduced in this way, hearing protection devices become mandatory. There is also an exposure limit value of 87dB(A)/140dB(C)peak', above which no worker can be exposed to.

However, it is not only in the workplace where people are exposed to harmful noise levels. Music venues, nightclubs and shooting ranges are just a few of the places at which these noise levels are regularly exceeded.

Hearing protection can be found in many different forms, whether standard ear-muff or ear-plug designs (known as ‘passive devices’) or more complex models incorporating electronic systems which react differently in varied noise environments, known collectively as ‘active devices’.

The performance of models in their passive state is dependent on several factors. The depths of the cups which enclose the ears, the headband force and the acoustic absorption of liners are just a few of the variables contributing to the performance of earmuffs, while size, fit and construction material generally govern the effectiveness of earplugs.