Understanding the difference between sound and noise levels can make a lot of difference to the ways in which we take measures for ear protection. Any sound which is harmful to the ears and body and irritating to the mind can be considered as noise. Various equipment are sued for determining the level of noise emanating from the source. Measurement of “weighting” in terms of time, frequency and the wavelength is used to assess the intensity. By analyzing the harmful effects of various intensity levels, we can suggest measures for complete ear protection.
Noise Assessment and Ear Protection
Sound Level Meter (SLM) is one of the devices used in assessing the intensity of noise. The sound of a motor cycle passing in front of our house can be noise source. A weaving machine running at high speed can generate noise. Gunshot at the hunting filed and the pistol shot from sports arena can also generate noise. By using the SLM we are able to measure the intensity and frequency levels of each type of noise accurately.
- Distance from the source of noise can be a major factor which affects the ear negatively. A shooter can experience shock waves from the gunshot more than a spectator who is sitting at a distance of about 100 meters. This is said to be due to the pattern in which noise spreads around the source and moves away from it. The standard shape of the noise waves is conical with the source as the center. People who are nearer to the center get affected more.
- Noise can also get reflected from the ground and the obstacles in the region around the source. For example you can consider the noise from a gunshot (sports arena) getting reflected from the ground, walls and other structures. This can effectively increase the intensity of waves which impact on the receiver. By keeping the SLM at various positions within the sports arena it is possible to assess the level of impact experienced by the shooter, spectators and the others present there.
Design of Ear Protection Devices
The design of ear protection devices (In this case we consider ear muffs) depends on the Noise reduction Rating (aerial path through the ear canal) and the Rear Ear Attenuation at Threshold (through the bone located at the rear ear) achieved by them.
- The design and tensile strength of the ear cup needs to be such that it can cover the external ear completely and seal the rear ear bone. With the right kind of foam pad in the interior walls and the cushion pad support, this device can filer more than 98% of the noise. The sound which goes through to reach the inner part of the ear will be within the audible range, hence harmless.
- The volume of empty space between the ear and the cushion pad and the padding at the edges of the cup can enhance the comfort levels of the wearer. One of the best designs recommended by ear specialists is incorporated into ClearArmor 141001 Shooters Hearing Protection Safety Ear Muffs.