HMEC 25-KA / HMEC 25-CA
A headset is comprised of two units, a headphone and a microphone. The HMEC
The microphone is a high quality
The headphone is a Sennheiser NoiseGard™ system. This is a dynamic headphone system which, in addition to reproducing the original audio signal, electronically cancels the low frequencies of the ambient noise. This active noise compensation operates on the principle that sound and
Clearly intelligible communication is ensured, and the pilot no longer has to turn the volume up to overcome ambient noise.
NoiseGard™ increases your comfort,
but it is not a medical hearing protection!
Active noise compensation with NoiseGard™
Noise compensation HMEC 25
Reduction/dB
0
10 | active | passive |
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20 |
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30
40 
20 | 100 | 1000 | 10000 | 20000 |
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| Frequency/Hz | |
Inserting the batteries into the battery box
The NoiseGard™ compensation circuitry is powered via a battery pack integrated into the headset cable. Insert two AA size batteries into the box as shown in the digram below.
Switching the power supply on/off
The on/off switch for the power supply of the compensation circuitry is at the front of the battery box.
Pilot light
An LED on the battery box indicates the battery status:
When the LED lights up green, the power supply for the compensation circuitry is sufficient.
When the LED is red, the batteries are almost flat and should be changed immediately. The NoiseGard™ system is still operational.
If the LED does not light up at all when the power supply is switched on, the batteries are completely flat. The headset is still operational but without the noise compensation.
The microphone is powered by the aircraft‘s internal power supply. Thus, it is independent of the batteries and always remains operational.
ON/OFF
LED
12 | 13 |
