Choosing the best hearing protection   HEARING damage is still in first position when it comes to occupational diseases, and where it is impossible to reduce the noise level of the source, hearing protection is required. Hearing damage occurs according to the dB level (how loud it is) and duration to exposure.  The following figure details the dB/duration relation to exposure to harmful noise.   Disposable, pre-shaped or custom molded?   Hearing protection specialist reports, that under certain legal guidelines, hearing protectors must be provided at an equivalent noise level of 80dB(A) and, at 85dB(A), the protectors "must" be worn. Various types of hearing protectors are available today. The question arises as to what type of hearing protection is best. No type of hearing protection is suitable for everybody at all times. The first question to be asked is: what level of protection is needed? A protector with a high level of attenuation may be considered as being the best protection, but this can be dangerous. Too much attenuation will reduce the ability for verbal communication, cause (psychological) isolation from the environment and, very important, decrease the perception of significant sounds and warning signals. Other important aspects to be considered are: Possible interference with other personal protective equipment. Work and climatologically circumstances. Duration of the noise exposure. Dirt and wearing comfort. Too much discomfort will cause the wearer to frequently remove the protector, which causes, even for very short periods, significant reduction of the actual protection level. In general, the best hearing protector is the one that is worn without interruption.  There are certainly no standard answers that can claim to be correct in every case. But for the best selection, good knowledge, of the typical properties, of the various types of hearing protectors is of great importance. Ear muffs. Earmuffs enclose the ear shell and are sealed to the head by soft cushions. A tensioning (head) band provides the necessary sealing force, and connects the cups. The cushions need to be regularly inspected, cleaned and replaced. Earmuffs are available with head, neck, chin and universal bands, and are available in helmet mounted versions. Advantages: Quick and easy donning and removal. Direct available and fits (nearly) everybody. No interference with auditory canal problems (inflammation, allergy). Practical in dirty environments. Good high frequency attenuation. Disadvantages: Inconvenient load on, and pressure to the head. Very uncomfortable at higher temperatures. Loss of "directional hearing" (localisation of the sound source). Limited compatibility with other personal protection equipment. Often limited low frequency attenuation. Earplugs. Earplugs are worn in the auditory ear canal or cover its entrance, to seal against noise. These can be provided with an interconnecting cord or headband and are either disposable or reusable.  Earplugs can be divided into three main groups; disposable, pre-shaped and custom molded. Disposable earplugs are made of foam material and shaped into a thin roll before insertion into the ear canal. After insertion the foam will return to its original dimension and so seal the ear canal.  These are intended for single use only. Correct (deep) insertion is essential for adequate noise insulation. Pre-shaped earplugs are inserted directly into, or covering the entrance of the auditory canal. These can be reused several times and are washable. Correct (deep) insertion is essential for adequate noise insulation. Advantages of disposable and pre-shaped earplugs: Direct available and fits most of the users. No inconvenient load on, or pressure to the head. Comfortable in warm environment. No interference with other personal protection equipment. Directional hearing is not affected. Disadvantages: Level of protection very dependent from accurate fitting - professional fitting rewquired. Proper function dependent from ear canal geometry. Custom molded earplugs are made-to-measure to the individual's auditory ear canal. Manan is a manufacturer of this type of hearing protection.  The plug provides the sealing, while an additional acoustic filter determines the actual attenuation required. Advantages: Maximum, especially long term, wearing comfort. Easy, safe and unambiguous to fit. Stable (form) fitting providing a high level of long term protection assurance. Availability of filters to suit the best level of attenuation and signal / sound perception. Ventilation of the ear canal, provided by the acoustical filter. Practical in dirty environments. Disadvantages: Not directly available (production time). Specifically personal bounded. Relatively high investment at the time of introduction, but cost effective in time. In summary, if the hearing protector is removed, even for only a short time, the level of protection is reduced substantially, so wearing comfort will significantly contribute to the acceptance of the user to wear the protectors continuously and so the effectiveness of this remedy. For those who only work occasionally and during shorter periods of time in high noise levels, earmuffs and standard earplugs will do well. For those who work structurally and for a longer time in a noise environment, custom molded earplugs are the most effective solution. It does not represent a luxury, but is in line with the requirements placed on hearing protection and seriousness of the problem.