Patent ID: 12219341

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

It is recognized that the controllers/devices as disclosed herein and in the attached Appendix may include any number of microprocessors, integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof), and software which co-act with one another to perform operation(s) disclosed herein. In addition, such controllers as disclosed utilizes one or more microprocessors to execute a computer-program that is embodied in a non-transitory computer readable medium that is programmed to perform any number of the functions as disclosed. Further, the controller(s) as provided herein includes a housing and the various number of microprocessors, integrated circuits, and memory devices ((e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM)) positioned within the housing. The controller(s) as disclosed also include hardware-based inputs and outputs for receiving and transmitting data, respectively from and to other hardware-based devices as discussed herein.

FIG.1generally depicts a system100for providing a virtual sound effect with one or more loudspeakers in accordance to one embodiment. The system100generally includes an audio input source102, a head related transfer function (HRTF) block104, a crosstalk cancellation block106, and at least one loudspeaker108(hereafter “the loudspeaker108” or “the loudspeakers108”). In one example, the at least one loudspeaker108(hereafter “the loudspeaker108” or “the loudspeakers108”) may be defined as in-wall loudspeaker(s) and may be positioned behind a wall or other barrier and is completely concealed (i.e., completely invisible) from being physically viewed by the listener. Additionally or alternatively, the loudspeaker108may be positioned in a floor or ceiling. While referencing to the invisible characteristic of the loudspeaker108, it is recognized that a loudspeaker grill that covers the loudspeaker108is also concealed or invisible and all that is visible to the listener is the wall, ceiling, or floor. In this case, there are no visual cues given to the listener with respect to the actual physical location of the loudspeaker108.

It is recognized that the audio input source102, the HRTF block104, and the crosstalk cancellation block106may be incorporated into a single device such as an audio playback device110. Alternatively, the audio play back device100may be distributed into a plurality of devices. The audio playback device110includes at least one controller103(“the controller121”) to execute any number of the operations as disclosed herein. In one example, the audio playback device110may correspond to a mobile device such as, but not limited to, a cell phone (e.g., smartphone, i-Phone®, etc.), a handheld computer (e.g., a personal digital assistant (“PDA”), etc.), a tablet (e.g., i-Pad®, etc.), a portable audio device (e.g., i-Pad®, etc.) or other suitable variant thereof. It is also recognized that the audio playback device110may be used in connection with a home audio system (e.g., TV, a media player such as, for example, a Blu-ray player, etc.) or for any system for that matter that generally plays back audio in a surround sound formal. In general, the crosstalk cancellation block106is configured to reproduce a desired signal at a single target position while cancelling out the sound at all remaining target positions.

The audio playback device110also includes a user interface111to enable listeners the ability to assign virtual locations for the loudspeaker(s)108. This aspect will be discussed in more detail below. The audio playback device110may include any number of transceivers112to facilitate wireless communication such as the wireless receipt of audio data and/or to facilitate wireless transmission of audio data to the loudspeaker108for playback in a listening environment115. The audio playback device110may utilize any number of wireless protocols to facilitate wireless communication. For example, the wireless protocol may include Bluetooth®, WiFi®, etc. The audio playback device110includes a controller114for executing code to enable the transmission of the audio data to the speakers108. The audio data may be in the form of, but not limited to, the following file formats: wav, mp3, wma, etc. The audio playback device110is further configured to communicate via the WiFi connection to a server116in order to retrieve and store any number of the foregoing audio data for playback.

The audio playback device110may also be configured to transmit data to the loudspeaker108when the audio playback device110receives the data from an external source via the one or more of the transceivers112. For example, the audio playback device110may receive the audio data as broadcast from a radio station (or tower) via frequency modulation (FM) or amplitude modulation (AM), etc. It is also recognized that the audio playback device110and the loudspeakers108may be integrated with at least one of the loudspeakers108and wirelessly communicate with any remaining loudspeakers108.

The audio playback device110may be implemented in any system that utilizes, but not limited to, a surround sound format. The audio playback device110may be used as a virtual upmixer and create any number of artificial multi-channel sources. Various nonlimiting examples include 5.1 channels or 7.1 channels. With respect to surround sound, this may involve various loudspeakers that surround the listener. Surround sound may involve a technique that enriches the fidelity and depth of audio reproduction by using multiple audio channels from loudspeakers that surrounds one or more listeners. In general, aspects disclosed herein may provide a virtualizer109that is provided by the audio playback device108(e.g., via the HRTF block104and the crosstalk cancellation block106) to deliver a full surround sound experience without visible loudspeakers108. It is also recognized that aspects disclosed herein may apply to any number of multi-channel encoding techniques such as, but not limited to, Dolby®, THX®, etc.

For example, the virtualizer109may be defined as block that includes crosstalk cancellation (via the crosstalk cancellation block106) and HRTF (via the HRTF block108) to provide a stereo output that mimics a similar sensation of a fully calibrated multi-channel audio system. In one example, the audio input source102may decode audio input sources into multi-channel audio (e.g., 5.1, 7.1, etc.). The HRTF block104may position audio objects to a corresponding location in space utilizing HRTF. The HRTF generally corresponds to a transfer function that describes the manner in which sound from a sound source will arrive at an eardrum of a user. This may also include influencing the shape of the listener's outer ear, the shape of the listener's head and body, and the acoustic characteristics of the environment. The HRTF may also affect if a listener can accurately perceive what direction sound is coming from. The crosstalk cancellation block106may cancel out the stereo cross contamination terms to widen a sound field in the listening environment. In general, audio signals that include directional cues are to be reproduced at the ear's of the listener. However, crosstalk may smear these cues and adversely affect the localization of sound. Thus, crosstalk cancellation may be used so that sound from the loudspeakers108to contralateral ears may be minimized.

FIG.2depicts an overall principle of combining crosstalk cancellation and HRTF in accordance to one embodiment.FIG.2generally depicts two loudspeakers108a,108bthat are positioned in front of a listener (or user)150. First and second HRTFs152a,152bare also shown inFIG.2. In general, each of the HRTFs152a,152bcorrespond to or describe the linear filtering of a sound signal in a free-field from different directions due to the physical propagation and scattering around a head of the listener150. When represented in a time domain, the HRTFs152a,152bmay also be called Head Related Impulse Responses (HRIRs). Such HRIRs comprise special sound localization cues and may be used for the design and reproduction of spatial audio systems. Generally, the HRTFs152a,152bcorrespond to filtering that is performed and measured to prevent reflections from walls, ceiling, and floor to affect the measured impulse responses. The HRTFs152a,152bmay first be characterized or established (i.e., or measured) and then stored in coded form within the HRTF block104. The notion of combining crosstalk cancellation and HRTF with the in-wall (or concealed) loudspeakers108adds the effect that the audio is coming any number of different directions while the loudspeaker(s)108are concealed from the listener150.

FIG.3depicts one schematic diagram of a measurement of the HRTF in accordance to one embodiment. The measurement of the HRTF may be performed in an anechoic chamber to prevent sound reflections from the ceiling, floor and walls. The listener150as illustrated inFIG.2is being replaced with a dummy head170inFIG.3. In this case, two microphones (not shown) are placed within the dummy head170and the dummy head170is placed on a turntable172. The dummy head170may be fixed at an origin of a coordinate system. Different angles of the HRTF may then be measured in the listening environment. Once the HRTF(s) are obtained, the audio playback device112may utilize digital filters (e.g., the HRTF block104) to virtualize loudspeaker positions for different channels of the surround sound as illustrated in more detail inFIG.4. For example, the input signals that are filtered by the HRTF block104may provide the direction of the sound image. With crosstalk cancellation, the real HRTFs in the actual system and environment are removed. In this case, the designed HRTF digital filters that form the HRTF block104may be developed and implemented according to a listener's (or manufacturers') desired virtual angles.

FIG.4depicts positions for the actual loudspeakers108a,108band positions for virtual loudspeakers200a-200efor a surround sound system. In general, the virtual loudspeakers200a-200ecorrespond to sound images as perceived by the listener150in the surround sound system. The loudspeakers108a,108bmay be the loudspeakers that are truly playing back audio for the listener150. However, the utilization of the HRTF block104that provides the HRTF(s) and the crosstalk cancellation block106that provides crosstalk cancellation which generates the virtual loudspeakers200a-200e(e.g., the sound images as perceived by the listener150). For example, virtual loudspeaker200amay be perceived by the listener150to be a left loudspeaker within the listening environment115, virtual loudspeaker200bmay be perceived by the listener150to be a center loudspeaker within the listening environment115, virtual loudspeaker200cmay be perceived by the listener150to be a right loudspeaker within the listening environment115, virtual loudspeaker200dmay be perceived by the listener150to be a surround right loudspeaker within the listening environment115, and virtual loudspeaker200emay be perceived by the listener150to be a surround left loudspeaker within the listening environment115.

FIG.4generally depicts that the virtual loudspeakers200a-200eare arranged in a polar coordinate system220(e.g., 0 to 360 degrees). Thus, the audio playback device102may enable the listener150the ability to assign a position for each of the virtual loudspeaker200a-200efor any coordinate of the polar coordinate system220via the user interface111. In this case, the HRTFs may be measured for every single (or one) degree up to 360 degrees. A listener150or designer may select one angle per one input channel as the virtual location (or virtual loudspeaker200a-200e). By combining the selected angle at the measured HRTF with the crosstalk cancellation, the listener may not perceive the sound coming from the loudspeaker108but from the virtual loudspeaker200a-200e. It is recognized that the user interface111may be in the form of a touch input device, voice command circuitry (e.g., microphones and circuitry that convert voice commands into electrical input signals) such a microphones, physical switches, or other suitable device that enables a listener150the ability to input information into an electrical device. In one example, the user interface11may graphically depicts the polar coordinate system220on a screen thereof and the listener150may simply assign the corresponding virtual loudspeaker200a-200eto a particular coordinate as illustrated in the system220as desired. It is recognized that aspects disclosed herein may alter the sound projection location as either a default position as indicated by, but not limited to, a surround standard (e.g., Dolby or Digital Theater Systems (DTS) surround loudspeaker position) or read custom user input(s) for each audio source as provided.

As noted above, in order to achieve wider sound field perception, the audio playback device110may employ the crosstalk cancellation block106to perform crosstalk cancellation. Thus, let us assume that G(rk) serves as the crosstalk cancellation function between the kth speaker and an optimized position r. The signals received by two cars are given by s,
s=HqEq. (1)

where H is the transfer function between the cars of the listener150and the loudspeakers108a,108b, and q is the source strength, which may be written as,
q=GdEq. (2)

where G is the matrix of G(rk) and d is the input signal. The error between the input signal and the received signal may be,
e=d−sEq. (3)

To minimize the error signals e, G may be given by:
G=[HHH]−1HHEq. (4)

To position audio objects to the corresponding location in space, the Eq. (4) may be modified as,
GT=CF[HHH]−1HHEq. (5)

where CFis the matrix of the head-related transfer functions.

FIGS.5and6depict an example of acoustic surfaces on a front and back of loudspeaker arrangements in accordance to one embodiment. Such acoustic surfaces may be considered as a solution using actuators. The actuators may transmit vibrations to a surface to deliver sound. In general, the actuators may correspond to drivers that are configured to generate vibration based on an input signal. Such actuators may be connected to a surface that vibrates and then ultimately delivers audio. This implementation may offer various advantages. For example, sound comes from a surface. Therefore, it is possible to conceal drivers within the loudspeakers108and embed the loudspeakers108within a wall of a listening environment thereby creating an invisible loudspeaker. Regarding the spatial cross model, which may suggest that visual modality often influences information from hearing, the loudspeaker108may be hidden along with any wires so that the spatial feeling is influenced by the audio. Thus, when the loudspeaker108is presented with virtual surround audio, the resulting audio experience may be comparable to watching a film in a movie theater. Due to the substantial size of the emissive surface of the loudspeaker, this may be more advantageous than that of a soundbar or to a TV and the sound stage may be wide and immersive. There is research that indicates that vision dominates what is heard by the listener. Therefore, vision has a greater influence on integrated localization than hearing. However, if listeners don't see the loudspeakers and the wires of loudspeakers are kept concealed, their sound localization may be dominated by sound, or desirably the virtual sound images by using HRTF and crosstalk cancellation.

FIG.7depicts a loudspeaker arrangement300in a listening environment302in accordance to one embodiment. In the arrangement300, the audio playback device110may be positioned within a television set312to playback audio data. It is recognized that the audio playback device110may be positioned in a larger device that is generally situated to provide audio data. Acoustic surfaces310a,310bmay be positioned on front sides of the loudspeakers108a,108b, respectively. By combining the virtualizer109in the audio playback device110along with the acoustic surfaces310a,310b, the arrangement300may be, for example, a fully immersive audio surround sound setup with a minimum setup procedure and may provide a visual and positive physical impact in the environment302. As shown, the virtual loudspeakers200a-200eare embedded within a wall and is invisible to the listener150.

FIG.8depicts a method400for providing a virtual sound effect in the listening environment115in accordance to one embodiment. In operation402, the audio playback device110receives an audio input signal from the audio input source102. As noted above, it is recognized that the audio input source102may be external to the audio playback device110. In another example, the audio input source102may be internal to the audio playback device110.

In operation404, the audio playback device110applies the HRTF to the audio input signal. In operation406, the audio playback device110applies the crosstalk cancellation to the audio input signal. In operation408, the audio playback device110generates an audio output signal after applying the HRTF and the crosstalk cancellation to the audio input signal. In operation410, the audio playback device110generates a location for at least one virtual loudspeaker200a-200ein the listening environment115to provide the effect that the at least one virtual loudspeaker200a-200eis playing back the audio output signal while the loudspeaker108in the listening environment115plays back the audio output signal.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.