The fundamentals of protective ear muffs cover the design and functional parameters as specified in the ANSI S-3.19 and CE-EN-352.1 standards. The most optimally designed ear muffs are over the head models with swivel types of ear cups. They provide maximum flexibility with heat absorption and air sealing characteristics. They are reliable under varying environmental conditions and work consistently over extended periods of time. They can withstand the enormous volume of pressure exerted by the impulsive noise which may go above the range of 164DB produced by gunshots.
Parts of Protective Ear Muffs
Simple and sophisticated parts of protective ear muffs include the ear cups, swivel knobs, headband, internal inserts, foam pads and the cushions. Ear cups are molded according to the dimensions specified by the designers. The depth of cup design provides optimum inner space for the inserts, foam pads and the cushions.
- Foam pads are lined with the internal walls of the cups. The recommended practice is to fix them with the help of screws, than using glue. This is to avoid peeling effects when exposed to high temperature zones.
- The cup dimension can be square shaped or rectangle, depending on the manufacturer specifications. Care is taken to cover the external ears and the rear ear bone completely.
- The fitting of ear cups are supported by the air sealing provided by the foam pads lined on the edges. Adjustments are made with the help of knob and screw provided at the headband. Swivel cups can be rotated within specific angle range to fit to the ears. Once properly fitted, the protective ear muffs can act as strong shields to deflect and absorb high pitch frequencies of noise.
NRR and SNR of Protective Ear Muffs
Noise Reduction Rating of the protective ear muffs is calculated based on the ANSI standards. The accepted value range is between 0DB and 33DB in the USA. Most of the standard devices range between 21DB and 26DB. Devices with higher NRR are considered to be more reliable and safe for usage under high pitch and impulsive noise conditions.
- Apart from ANSI, the other entity which is responsible for the evaluation of protective ear muffs is the Environment Protection Agency (EPA) in the USA. In combination with the ANSI standards, they evaluate the quality parameters of ear protection muffs in the range of frequencies between 64HZ and 8000+HZ. This is for the long term exposure to hazardous noise.
- Muzzle blast noise is mostly produced by jet aircrafts (that travel at high speeds, often exceeding the speed of sound) and gunshots. The intensity of waves is so high that it can create cracks on glass surfaces when exposed frequently. The protective ear muffs are designed by keeping this sort of impulsive noise in view.
- The volume of shock waves deflected by the ear cups and absorbed by the foam can cause severe levels of stress on them. Hence the design parameters are maintained at highest levels. ClearArmor 141001 Shooters Hearing Protection Safety Ear Muffs are considered to be compatible for varying noise frequencies and working conditions.