Description Model H3442 Behind-the-Head Style (BTH) Noise-Cancelling M-7A amplified electret microphone Microphone on/off button BTH style for applications requiring hard hats or protective headgear Flex-wire boom for easy, 'one touch' microphone placement Boom rotates 200° for left or right placement Contoured, undercut 'Comfort-Gel' ear seals for maximum comfort Rugged construction 6 ft. coil cord Noise Reduction Rating (NRR): 23 dB Part Number: 40583G-03 Noise Attenuation Data NRR23 dB Frequency (Hz) 125 250 500 1000 2000 3150 4000 6300 8000 Attenuation (dB) 14 21.1 31 37.1 33 35.6 35.6 38 36.5 Standard Deviation 2.7 2.7 2.8 2.7 3.3 3.5 3.2 2.9 3.4
