Sennheiser HDC 451 Reduction of subjectively perceived noise level, Switching ON/OFF, On/Off Led

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Reduction of subjectively perceived noise level

NoiseGard™ are dynamic stereo headphones which, in addition to transmitting an audio signal, also electronically compensate low-frequency noise. This active noise compensation functions according to the physical principle that noise and „anti- noise“ (exactly reversed in phase) cancel each other out.

So, now you can enjoy your music undisturbed, without having to turn the volume up so high that surrounding noise is completely drowned out.

The NoiseGard™ compensation electronics in the headphone requires its own power supply. This is provided by the power supply unit which is fixed to the cable.

The headphone is connected in the usual manner by a 3.5-mm stereo jack plug, by an adapter to two 3.5-mm mono jack plugs (in aircraft) or by means of a 6.3-mm adapter (to the hi-fi unit at home). Both adapters are supplied.

Noise compensation with NoiseGard™

NoiseGard™ HDC 451

The first „open-air“ stereo headphone with NoiseGard™ active noise compensation

At just 110 g, this „open-air“ stereo headphone with active noise compensation is extremely light and provides excellent wearer comfort. Sound coupling to the ear is directly on the ear.

￿When you are wearing the NoiseGard™ HDC 451 you will still be able to join in conversation - the voice of the person talking to you is scarcely changed, since the speech frequency is practically unaffected by compensation.

￿Warning or emergency signals remain audible.

￿Understanding speech is even improved by NoiseGard™, as „upward-masking“ by low-frequency sound is eliminated.

Switching ON/OFF

ON/OFF switch for the power supply to the compensation electronics is situated on the battery box. A green LED lights up as a check.

If the power supply is switched off or the batteries are worn out, the headphone can still be used as a normal headphone without noise compensation.

Inserting the batteries in the power supply unit

Attenuation in dB

0

Warning Signal

Human speech

Reduction of the

subjectively perceived

noise level with

Noisgard

10

20

100

200

500

1000

2000

5000

Frequency / Hz

ON/OFF

LED

8

9

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