User manual SENNHEISER HMEC 45-KAX

[. . . ] During takeoff and landing, the noise level is even higher. To be able to understand radio traffic in spite of the noisy environment, the ATC signal level must be set to at least 95 dB (A). [. . . ] Permanent hearing loss caused by the continuous noise in aircrafts is the reason why many pilots became prematurely disabled and pilots lost their pilot´s license. Circumaural communication headsets provide noise attenuating properties and are commonly used to address this problem. However, the noise attenuation of these headsets is uneven. High frequencies are reduced considerably, but low frequency wind and engine noise, the most prominent noise in many of today's aircrafts, is attenuated very little. In response to these problems, Sennheiser electronic has developed an active noise compensation system which, combined with a high-quality passive ear defender, provides consistent noise attenuation over the entire audio range. The overall noise level is reduced so that the radio volume can be turned down but enough noise still remains for the pilot to safely monitor the aircraft engines. The remaining signal (noise) is then filtered and inverted and the radio signal is added back in. Eventually, the entire signal is amplified and fed back to the transducer in each ear cup. Since the noise component of the signal is inverted, it cancels the noise signal coming through the ear cup. The radio signal remains unaffected, as it was not processed through the cancellation circuits. The HMEC 45-KAX / HMEC 222-III NoiseGard is a closed ear defender style headset with active noise compensation for use in propeller aircrafts and turboprops. Consistent noise attenuation over the entire audio range up to 40 dB State-of-the-art transducer technology ensures optimum intellegibility Electronic circuitry incorporated into headphone system Automatic deactivation of the active noise compensation circuits in case of eardamaging feedback oscillation, subsequently fail safe operation With the supply voltage switched off, the headset functions as a conventional noise attenuation headset The boom microphone can be rotated in all directions and can be worn on either the right or left side A noise-canceling electret-microphone with preamplifier ensures perfect transmission while suppressing ambient noise The headset is ergonomically designed and functionally optimized to give the utmost wearing comfort Collapsible headband for easy transportation ACX-1 ACX-2 Adapter cable for the power supply of only one headset Adapter cable for the power supply of two headsets These adapter cables are also available with a right angle plug which features a 7. [. . . ] Consistent noise attenuation over the entire audio range up to 40 dB State-of-the-art transducer technology ensures optimum intellegibility Electronic circuitry incorporated into headphone system Automatic deactivation of the active noise compensation circuits in case of eardamaging feedback oscillation, subsequently fail safe operation With the supply voltage switched off, the headset functions as a conventional noise attenuation headset The boom microphone can be rotated in all directions and can be worn on either the right or left side A noise-canceling electret-microphone with preamplifier ensures perfect transmission while suppressing ambient noise The headset is ergonomically designed and functionally optimized to give the utmost wearing comfort Collapsible headband for easy transportation ACX-1 ACX-2 Adapter cable for the power supply of only one headset Adapter cable for the power supply of two headsets These adapter cables are also available with a right angle plug which features a 7. ACX-11 ACX-22 Adapter cable for the power supply of only one headset Adapter cable for the power supply of two headsets ACX-1 ACX-2 Adapter cable for the power supply of only one headset Adapter cable for the power supply of two headsets These adapter cables are also available with a right angle plug which features a 7. [. . . ]