In response to these problems, Sennheiser has developed an active noise compensation system – NoiseGard™ – which, combined with a high-quality passive hearing protector, 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.

A

NoiseGard™ active noise compensation is achieved by generating a signal identical in sound pressure level but exactly reversed in phase to the noise signal, the effect being that the out-of-phase signal cancels most of the noise signal.

Active noise compensation is accomplished in the following manner: Each earcup includes a microphone, a feedback control circuit, and a transducer to reproduce both the communication and the noise cancelling signal. The feedback control microphones sense the total sound pressure within each earcup resulting from both the desired radio signal from the receiver and the undesired noise that has come through the earcup. The microphone signal is amplified and the radio signal is subtracted from it. 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 earcup. Since the noise component of the signal is inverted, it cancels the noise signal coming through the earcup. The radio signal remains unaffected, as it was not processed through the cancellation circuits.

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HD400 specifications

The Sennheiser HD400 series represents a thoughtful blend of innovation, comfort, and superior audio quality, catering to both casual listeners and audiophiles alike. Renowned for their commitment to sound excellence, Sennheiser has integrated advanced technologies into the HD400 headphones, ensuring an immersive listening experience.

One of the standout features of the HD400 series is its exceptional sound quality, achieved through high-quality transducers that deliver a balanced and detailed audio spectrum. Whether listening to classical music or modern pop, users can expect clear highs, robust mids, and deep bass. This well-rounded sound signature makes the HD400 versatile for various genres and audio applications.

Comfort is paramount in the design of the HD400. The headphones feature plush ear pads and an adjustable headband, allowing users to enjoy long listening sessions without discomfort. The lightweight design further enhances usability, making these headphones perfect for both at-home listening and on-the-go use. Additionally, the ergonomic design ensures a secure fit, reducing sound leakage and providing an immersive experience.

Equipped with advanced connectivity options, the HD400 series primarily supports wired connections, ensuring minimal audio latency and maximum sound fidelity. This wired setup is complemented by a high-quality audio cable that provides flexibility and durability, crucial for everyday wear.

Sennheiser is known for its noise isolation technology, which is prominently featured in the HD400 series. This technology effectively blocks out ambient noise, allowing listeners to delve deep into their audio without distractions. This feature is particularly useful in crowded environments or during commutes.

Durability is another characteristic of the HD400 series. Constructed with high-quality materials, these headphones are designed to withstand daily use while maintaining their aesthetic appeal. Sennheiser also offers a limited warranty, underscoring their confidence in the product's longevity.

Overall, the Sennheiser HD400 series harmonizes comfort, sound quality, and innovative technology, making it an ideal choice for anyone seeking an elevated audio experience. With their thoughtful design and performance, they appeal to a broad audience, whether for casual listening or professional audio applications. The Sennheiser HD400 stands as a testament to the brand's commitment to audio excellence.
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