Frag Out! Magazine
Issue link: https://fragout.uberflip.com/i/739629
Earplugs consist of a noise-cancelling ear tip that is usually made of a foam insert with a hear-through channel that sound goes through from the speaker to the microphone. Less frequently, those are silicone ear tips as in semi-active solutions, although some of models may be attached to ear tips of semi-active plugs. Foam and silicone plugs have sizes that are usually labeled with colors. In most cases, there is also a possibility of using custom-shaped, silicone tips, which improve noise canceling and increase comfort of use, because they perfectly fit to user's ear (they are casts base on the wax form of the channel). SNR of foam ear tips is around 28-30 (in case of the best silicone ear tips, the value may even be 35-38 dB). Ear tips have a microphone that collects ambient sound, speaker, and – if the set has the option to connect a hand radio – an in-ear microphone for communication. Microphones that collect ambient sounds may be in-built in the body of the plug (e.g. Silynx ones) or protrude over it in a foam cover (e.g. NACRE). Plugs of the first type are flat and practically do not protrude from the auricle. Plugs of the second type, due to application of a foam cover, generate less whistling sounds in the wind. Usually, plugs are divided into right and left one. In case of in-ear hearing protection system, voice is gathered from the ear channel, so that there is no need to use external microphones, although some sets offer such an option. Civilian versions are an exception; they work mobile phones – in such devices, the microphone is placed on the wire with earplugs, same as in casual headphones. On the cover of the microphone, there is also a button to receive/ reject call that, in case of connecting an MP3 player, is used as a play control button. What's interesting – some control units may be connected to active muffs. The electronic circuit for control and noise cancellation and all the buttons are on separate control unit. That unit also includes the battery compartment. The simplest sets are not capable of connecting external devices, other sets allow connecting a mobile phone or MP3 player. The majority of them has been designed to work with radios – from one to two (or two + vehicle intercom). The number of control buttons depends on the fact whether there is a possibility of connecting external devices and number of them. However, it may be assumed that they are divided into PTT buttons and device control buttons (On/Off, Volume Up/Volume Down, Channel Selection). This replaces completely the separate PTT switches. www.fragoutmag.com