On June 19, 2014, the US Patent & Trademark Office published a patent application from Apple that reveals that well before Apple acquired Beats Music, they were already working on over-the-ear headphones. Specifically, Apple's invention relates to a hybrid adaptive headphone having active noise control capability and passive noise control capability. Apple is on a roll of late regarding new over-the-ear headphones features. At the end of May we posted a patent report titled "Apple to Add Presence Sensors to EarPods & Future Beats Headsets."
Apple's Patent Background
Whether listening to a portable media player while traveling, or to a stereo or theater system at home, consumers often choose headphones. Headphones typically include a pair of earcups which encircle the user's ears and are held together by a headband. Headphones can be classified into two general categories based on the design of the earcups, namely closed-back or open-back earcups. Closed-back earcups surround the user's ears and have a sealed back. Open-back earcups also surround the user's ears but have a back which is open to the ambient environment surrounding the earcup.
Both the closed-back and the open-back designs have their own acoustic advantages and disadvantages. Representatively, closed-back earcups have good sound isolation since they are sealed off from ambient noise. In addition, the size and clamp force of the earcups can also be modified to further increase sound isolation. Features of the closed-back design, such as the sealed back, size and clamp force of the earcups allow this design to mechanically or passively attenuate any ambient noise.
In some cases, however, closed-back earcups can also make use of an electronic active noise control (ANC) system for additional sound isolation. An ANC system is a noise cancellation system which can attenuate or cancel noise within the earcup by emitting an "antinoise" signal, which is an audio signal having, in theory, the same amplitude and opposite phase to that of the noise such that they cancel each other out.
Due to the closed design of closed-back earcups, however, they have stronger resonances. For example, standing waves can accumulate in the earcups. These standing waves can degrade sound quality and reduce the feeling of openness, which is often desired by a user. In addition, in a quiet environment, residual noise from electrical components within the earcup (e.g., a driver or microphone within the earcup housing) may be heard by the user.
Open-back earcups, on the other hand, have good sound quality due to their low resonances, feel more open to the user, and allow ambient noises to be used to mask some of the residual noises which would otherwise be heard by the user.
Open-back earcups, however, cannot be used in noisy environments because their passive attenuation is by definition poor. In addition, since open-back earcups are substantially open to the ambient environment, ANC systems may not be able to efficiently cancel the ambient noise entering the earcup through the open back.
Apple Invents Hybrid Adaptive Headphones
Apple's invention relates to a hybrid adaptive headphone having active noise control capability and passive noise control capability.
Apple notes that an embodiment of their invention is a hybrid adaptive noise-cancelling headphone which boasts advantages of both closed-back earcup and open-back earcup designs, as a function of the environment.
Representatively, the headphone may include an earcup housing having a driver positioned therein for outputting sound to a user's ear. The driver may be positioned between a front portion of the housing (which is dimensioned to encircle the user's ear) and a back portion of the housing.
An active noise control assembly and a passive noise control assembly may be associated with the earcup housing. The active noise control assembly may include an ambient microphone capable of detecting an ambient noise outside of the housing (also referred to as a reference microphone) and an error microphone capable of detecting earcup (residual) noise (inside of the housing).
Based on the detected ambient noise and the earcup noise, active noise cancellation within the headphone is either enabled or disabled. The passive noise control assembly may include an acoustic valve associated with an acoustic vent formed within the earcup housing. The acoustic valve is capable of being modified between an open configuration to decrease sound attenuation and a closed configuration to increase sound attenuation in response to the detected ambient noise so as to improve an acoustic performance of the earcup.
An operation of the active noise control assembly and the passive noise control assembly may be controlled by a processor configured to receive one or more of an ambient noise electrical signal and an earcup noise electrical signal output by the ambient microphone and the error microphone, respectively. The processor may compare the ambient noise electrical signal or the earcup noise electrical signal to a predetermined threshold value. Based on the comparison, the processor may instruct the passive noise control assembly to open or close the vent, and the active noise control assembly to enable or disable ANC.
Apple's patent FIG. 1A noted below illustrates a schematic diagram of one embodiment of a hybrid adaptive headphone having a passive noise control assembly in a closed vent position and FIG. 1B in an open vent position.
Apple's patent FIG. 2A noted below illustrates a schematic diagram of one embodiment of a hybrid adaptive headphone having a passive noise control assembly in a closed position and in 2B with the passive noise control assembly in the open position.
Apple's patent FIG. 3 illustrates a block diagram showing one embodiment of an operation of a noise control assembly.
Apple credits Yacine Azmi as the sole inventor of patent application 20140169579 which was originally filed in Q4 2012. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
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