你可以隨身攜帶。 ——多功能且充滿活力的全新HD 4系列通過一副耐用、封閉包耳式耳機中為你帶來完整的Sennheiser質量，從而滿足你的日常聆聽需求
HD 4.40 BT無線耳機可以讓你自由運動。因為它沒有線纜的束縛。同時這款採用無線核心技術和音頻編解碼技術的頭戴耳機能夠實現可靠穩定的無線傳輸以及無線方式高保真聲音質量。通過近場通信（NFC）技術保證了與兼容產品之間進行快速便捷的配對使用。
想進行電話呼叫、曲目切換、音量調整嗎？使用固定於HD 4.40 BT無線耳機耳罩上的觸控式控制開關和集成式咪高峰就可以輕鬆自如的完成這些需求。快來試一試吧！
HD 4.40 BT無線耳機隨著你到任何地方-同時讓你有彷如置身於家中的享受。包耳式設計以及厚實、人體工程學設計的耳墊非常適合長時間使用。堅固耐用的可折疊頭帶設計令它安全的存放於保護袋中。
高雅的外觀設計-使用堅固耐用高質量的材料製造：這就是HD 4.40 BT無線耳機的設計製造理念。它的弧形框架不僅具有極為舒適的佩戴性，而且也使之歷久彌新。
CIRCUMAURAL headphones (sometimes referred to as "Around Ear" headphones) encircle the ear creating a seal thereby effectively reducing ambient noise from getting to the ear. This is known as passive noise reduction.
This type of headphone is most effective in a high noise environment where it's necessary to eliminate as much of the environmental noise as possible for effective communication.
While the overall transmission range for wireless headphones is mostly determined by the wireless technology being utilized by the individual wireless headphone product there are multiple external factors (like obstacles, audio signal strength, wireless signal congestion, etc) that can effect the wireless signal transmission range of wireless headphones.
Obstacles are one of the main factors that can effect the transmission range of the wireless signal. While the wireless signal (with the exception of infrared signals) can pass through obstacles (like walls) ultimately range will be affected (likely reduced) by passing through these obstacles and the more dense the obstacle the greater the effect will be on the signal. For example a signal passing through a glass window won't be affected very much whereas a signal passing through a concrete wall will be effected much more greatly. Having a clear line of sight does provide the best transmission range.
The audio signal being output by your audio source to the transmitter of the headphones is another key factor in transmission range. A weaker audio signal going into the transmitter means the transmitter has a weaker signal to work with which can in turn reduce the transmission strength which ultimately affects range. Ensure that your audio source is outputting the best possible signal for the transmitter to use.
A2DP (Advanced Audio Distribution Profile) is a Bluetooth profile that defines how multimedia audio can be streamed from one device to another over a Bluetooth connection.
Most Sennheiser Bluetooth headphones utilize the A2DP profile as it allows for the best audio transmission over Bluetooth hence providing the best audio in the headphones.
NOTE: If the device you are connecting to does not support A2DP there may be connectivity issues between the Sennheiser unit and the device. In situations like this most Bluetooth Chipset manufacturers offer firmware updates to the Bluetooth chip to allow the A2DP profile to be utilized.
The Apt-X refers to a built in codec that takes the available Bluetooth audio and enhances it so you have a superior sound. In order for the Apt-X codec to be utilized both the headphones and the device that they are connected to need to have the Apt-X codec built in.
If the codec is not available in the device you are connected to the headphones will still work however you will not have the benefit of the Apt-X codec. If a device does not have the Apt-X codec built in you can purchase a device called a Bluetooth dongle with the Apt-X codec that will connect to your device and allow you to utilize the codec.
NOTE: Apt-X will not affect Bluetooth connectivity with a device.
Our Wireless Headphone Systems can be connected into virtually any audio device and it is just a matter of identifying the appropriate audio output port and then having the appropriate connecting plug or component.
The type of connector you have available will depend on the Sennheiser Wireless Headphone System that you choose. The type of audio output that you will have available to connect into will depend on the audio device you are connecting to.
Typical audio output ports include:
- 3.5mm headphone port
- red and white RCA audio output ports
- digital audio output (either optical or coaxial)
NOTE: In some instances an adapter or extra component will be needed to make the appropriate connection.
For example to change a 3.5mm headphone plug to an RCA connection you would use a female 3.5mm to male RCA adapter.
For example to change an analog connection (3.5mm headphone plug or red and white RCA plugs) to a digital connection (ie: optical) you would use a digital to analog decoder (like the OREI DA 34).
The wireless headphones that utilize a digital transmission signal operate in the unlicensed 2.4 Ghz range as do many other wireless devices (like WiFi routers, wireless printers, etc) and the headphones have a specific frequency range on which they can operate. The headphones scan the local wireless signal environment and then automatically select an unused frequency within their designated range. The headphones are designed to work in conjunction with other wireless devices without the different devices interfering with each other.
Typically the bandwidth of the WiFi router is greater than that of the headphones and it actually encompasses the bandwidth that the headphones want to use. Most of the time the two signals are away from each other and there is no issue. Occasionally if the WiFi router has established it's signal in the bandwidth that the headphones want to use then the two signals butt up against each other this can cause issues. Sometimes it is possible to change the WiFi router frequency manually by using a switch on the router itself.
In situations where the WiFi router cannot be changed manually the simple solution is to turn off the headphones and the WiFi router. Start the headphones and let them run for 15 minutes to establish their signal and then turn on the WiFi router. The WiFi router will "see" the signal of the headphones and establish it's own signal in a different part of the bandwidth and the two devices will work without interfering with each other. NOTE: Once this process has been done the signals are established and will remain established even with a device is turned off.
If the above solution does not resolve the issue it may be a situation where the wireless environment is too crowded and the multiple wireless signals keep butting up against each other and causing issues. To resolve this some wireless signals would need to be removed from the environment (ie: turned off). For example if a wireless printer was turned on it is creating wireless signal that would be part of the wireless signal congestion. If the printer is not used all the time then it could be turned off to reduce the congestion and allow the other wireless devices (like the headphones) to work.
Near-field communication (NFC) is a set of communication protocols that enable two electronic devices, one of which is usually a portable device such as a smartphone, to establish communication by bringing them within 4 cm (1.6 in) of each other.
NFC devices are used in contactless payment systems, similar to those used in credit cards and electronic ticket smartcards and allow mobile payment to replace/supplement these systems. NFC-enabled devices can act as electronic identity documents and keycards. NFC offers a low-speed connection with simple setup that can be used to bootstrap more capable wireless connections.