Patent Application
20220322021
The present disclosure relates to audio processing and sound generation. More specifically, the present disclosure relates to an audio device comprising a plurality of loudspeakers for generating a three-dimensional soundfield as well as a corresponding method.
Soundbars comprising a plurality of transducers are well-established for different media applications, such as soundbars for television, smartphones and tablet computers. However, many of these conventional audio solutions are not perceived pleasant to the user. In particular, this is because many of these applications do not provide a comfortable 3D audio experience to the user.
There is a need for an audio device and method providing an improved three-dimensional sound experience.
It is an object of the disclosure to provide an audio device as well as a corresponding method allowing for an improved three-dimensional sound experience.
The foregoing and other objects are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.
According to a first aspect, the present disclosure relates to an audio device for generating a three-dimensional soundfield. The audio device comprises a housing having an elliptical torus shape and a plurality of loudspeakers. Moreover, the audio device comprises processing circuitry configured to process a plurality of input signals to obtain a plurality of output signals and output the plurality of output signals to the plurality of loudspeakers. The processing circuitry is configured to process the plurality of input signals such that: a first pair of the plurality of loudspeakers form a first dipole for crosstalk cancellation between left hand side signal components and right hand side signal components in a first frequency range of the soundfield; a second pair of the plurality of loudspeakers form a second dipole for crosstalk cancellation between left hand side signal components and right hand side signal components in a second frequency range of the soundfield; and a third pair of the plurality of loudspeakers form a third dipole for sound elevation of the soundfield. The first frequency range extends to higher frequencies than the second frequency range, i.e. the upper bound of the first frequency range is larger than the upper bound of the second frequency range, and a distance between the loudspeakers of the plurality of loudspeakers forming the first dipole is smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the second dipole.
Thus, the audio device according to the first aspect allows to provide an improved three-dimensional sound experience by employing a first and a second dipole for crosstalk cancellation and a third dipole for sound elevation. Embodiments of the audio device have a toroidal housing and loudspeakers may be implemented in the housing. The soundfield may comprise a main radiation direction, which is based on the specific orientation of the loudspeakers mounted in the housing. Hereby, the main radiation direction may define an area proximate to which a listener may perceive a preferably high-quality 3D audio experience. The elliptical torus shape comprises as a specific case a circular torus shape. The elliptical, in particular circular arrangement of the loudspeakers within the toroidal housing may additionally define a compact geometry that may be useful for improved handling. Moreover, the elliptical, in particular circular arrangement of the loudspeakers enables to accommodate the loudspeakers in a manner, which enables to realize variable dipole distances in both horizontal and vertical directions. This allows to accurately adapt the frequency ranges of the soundfield according to the respective listener's needs by adapting the dipole distances of the horizontal and vertical dipoles accordingly. Additionally, using a plurality of horizontal dipoles and vertical dipoles having different dipole distances based on the elliptical, in particular circular arrangement enables the use of a preferably high total frequency bandwidth regarding both crosstalk cancellation portions and sound elevation portions. The loudspeakers can be coplanar or at least substantially coplanar and can be shared for horizontal and vertical dipole processing. Embodiments of the present disclosure also provide a portable and wearable audio device. Embodiments of the present disclosure also provide an accommodation area within the opening regime of the elliptical torus shape that may potentially be associated with a TV or another image or video device. According to some of these embodiments, the view direction of such a visual device may be adapted in accordance with the main radiation direction of the soundfield.
As used herein, “crosstalk cancellation” refers to an audio technique for delivering virtual 3D sound to a listener via two or more loudspeakers, wherein source signals are pre-processed prior to loudspeaker reproduction in order to ensure that first (e.g. left hand side) signal components of the loudspeakers may be prepared for and transmitted to a first ear (e.g. left ear) of the listener, and second (e.g. right hand side) signal components of the loudspeakers may be prepared for and transmitted to a second ear (e.g. right ear) of the listener different from the first ear. In doing so, virtually a substantial portion of acoustic crosstalk, in ideal circumstances all acoustic crosstalk, is cancelled out at the other ear and no significant reverberation is present. According to some embodiments, an angle Δy defined by the propagation direction of dipoles formed for the first ear relative to the propagation direction of dipoles formed for the second ear may be in the range of 0°≤Δδ≤15°.
In further (opposite) embodiments, the first signal components may be right hand side signal components and the first ear may be the right ear and the second signal components may be left hand side signal components and the second ear may be the left ear. For ease of understanding, the following description will describe embodiments, where the first signal components are the left hand side signal components and the first ear the left ear and the second signal components are the right hand side signal components and the second ear is the right ear, however all explanations correspondingly also apply to opposite embodiments.
As used herein, “sound elevation” refers to the perception of sound originating from sound sources, wherein the sound perception occurs at positions outside the 2D horizontal plane. Audio techniques for delivering such virtual 3D sound to a listener use, for instance, reflections by the ceiling of a room for simulating virtual source(s) located at a greater, i.e. “elevated” height than the original source(s). According to some embodiments, a propagation direction of a sound elevation portion of the soundfield may be adapted in accordance with dimensions of a type of location for which the machine is provided. According to some embodiments, angles Δβ1 and Δβ2, respectively defined by a normal vector of a main plane defined by the elliptical torus shape of the housing and the propagation direction of the sound elevation portion of the soundfield may be in a range of 0°≤Δβ1≤75° and 0°≤Δβ2≤75°, wherein the propagation direction of the sound elevation portion of Δβ1 may be directed upwards and the propagation direction of the sound elevation portion of Δβ2 may be directed downwards. In certain embodiments, angles Δβ1 and Δβ2 may be in a range of 20°≤Δβ1≤60° and 20°≤Δβ2≤60°. In certain embodiments, angles Δβ1 and Δβ2 may be in a range of 40°≤Δβ1≤50° and 40°≤Δβ2≤50°. The specific ranges indicate herein enable a preferably good 3D sound experience to a listener having a preferably designated distance from the loudspeakers of the audio device. According to some embodiments, such preferably designated distance from the loudspeakers may be in a range extending from 100 cm to 400 cm.
The first frequency range may at least partially overlap the second frequency range. Alternatively, the first frequency range and the second frequency range may be non-overlapping. The second frequency range may extend to lower frequencies than the first frequency range. Further, a median frequency value of the second frequency range may be smaller than a median frequency value of the first frequency range.
The plurality of loudspeakers may be evenly distributed along the elliptical torus shaped housing. The first pair of loudspeakers forming the first dipole for crosstalk cancellation and the second pair of loudspeakers forming the second dipole for crosstalk cancellation may be arranged in the elliptical torus shaped housing such that the first dipole extends in a parallel or at least substantially parallel displaced orientation to the second dipole. The first pair of loudspeakers forming the first dipole for crosstalk cancellation and the third pair of loudspeakers forming the third dipole for sound elevation may be arranged in the elliptical torus shaped housing such that the first dipole extends in a perpendicular or at least substantially perpendicular orientation to the third dipole. The second pair of loudspeakers forming the second dipole for crosstalk cancellation and the third pair of loudspeakers forming the third dipole for sound elevation may be arranged in the elliptical torus shaped housing such that the second dipole extends in a perpendicular or at least substantially perpendicular orientation to the third dipole.
As used herein, “substantially horizontal”, “substantially vertical”, “substantially parallel”, “substantially perpendicular” and similar expressions define a respective angular orientation with a deviation of less than 35°less than 25°, less than 15°, or less than 5° from a strict horizontal, vertical, parallel or perpendicular angular orientation. According to some embodiments, these terminologies may be used to correlate geometrical and structural aspects of the audio device with each other in a relative manner. According to further embodiments, these terminologies may be used to correlate sound emission aspects of the audio device with each other in a relative manner. According to some embodiments, these terminologies may be used to correlate geometrical and structural aspects of the audio device with sound emission aspects of the audio device in a relative manner.
The elliptical torus shaped housing may be configured to be arranged in an operation orientation such that a main plane defined by the housing, i.e. the plurality of loudspeakers mounted in the housing is a vertical or at least a substantially vertical plane. Hereby, the operation direction may be defined and aligned, respectively by a user, who intends to listen to the soundfield of the audio device. For instance, the housing of the audio device may be configured to be mounted to a wall or placed on a table such that in the operation orientation the plane defined by the housing is a vertical or at least substantially vertical plane. In the operation orientation of the audio device, the first pair of loudspeakers may form a first horizontal or at least substantially horizontal dipole for crosstalk cancellation, the second pair of loudspeakers may form a second horizontal or at least substantially horizontal dipole for crosstalk cancellation, which is located parallel or at least substantially parallel to the first horizontal or at least substantially horizontal dipole, but at a different vertical height than the first horizontal or at least substantially horizontal dipole, and the third pair of loudspeakers form a vertical or at least substantially vertical dipole for sound elevation of the soundfield, which is orientated perpendicular or at least substantially perpendicular to the first and/or second horizontal or at least substantially horizontal dipoles.
According to further implementations, the first frequency range (e.g. first audio frequency range) comprises a high frequency (HF) range and/or the second frequency range (e.g. second audio frequency range) comprises a mid frequency (MF) range. Advantageously, this allows providing crosstalk cancellation in the HF range by the first dipole having the smaller dipole distance. Further, this allows providing crosstalk cancellation in the MF range by the second dipole having the larger dipole distance. Thus, the crosstalk cancellation is achieved (at least more accurately) over a larger total frequency range. According to some implementations, the MF range may be within a range of 102 Hz≤MF≤104 Hz and/or the HF range may be above 103 Hz. Such an acoustic dipole distance may be defined as the distance in between the positions of two acoustic transducers forming an acoustic dipole.
In a further possible implementation form of the first aspect, at least one loudspeaker of the first or second pair of loudspeakers is also part of the third pair of loudspeakers. Advantageously, this allows synergistically using one or more of the plurality of loudspeakers for more than one dipole and thereby enables a more compact housing as well as a less complex technical implementation.
In a further possible implementation form of the first aspect, the housing mounting the plurality of loudspeakers has a circular torus shape. Thus, the use of identical or at least similar dipole distances in a horizontal and vertical direction is enabled, which consequently enables to transmit identical or at least similar dipole frequencies regarding both crosstalk cancellation portions of the soundfield and sound elevation portions of the soundfield. This may be considered pleasant by a listener listening to the soundfield of the audio device and improve the overall audio quality. Additionally, similar dipole frequencies regarding both crosstalk cancellation portions of the soundfield and sound elevation portions of the soundfield may be even achieved in this case using at least partly the same loudspeakers regarding both vertical and horizontal dipole. In doing so, the number of loudspeakers required for providing crosstalk cancellation and for sound elevation may additionally be minimized.
In a further possible implementation form of the first aspect, an arrangement of the loudspeakers of the plurality of loudspeakers forming the first dipole defines a first dipole orientation and arrangement of the loudspeakers of the plurality of loudspeakers forming the third dipole defines a third dipole orientation, wherein a first dipole orientation angle η1 defined by the third dipole orientation relative to the first dipole orientation is in a range of 65°≤η1≤115°. Thereby, it is enabled to provide an improved three-dimensional sound experience by expanding well-established two-dimensional crosstalk cancellation technique by means of additional sound elevation portions providing an additional dimension of the soundfield, wherein the sound elevation portions are transmitted in specific angular directions, in which they minimally affect dipole fields relating to crosstalk cancellation. Consequently, three-dimensional sound experience may be achieved without significantly interfering with the well-established crosstalk cancellation technique.
As used herein, the “dipole orientation” may be defined as an arrangement of loudspeakers forming an acoustic dipole relative to each other. According to some embodiments, the dipole orientation refers to an arrangement of two loudspeakers relative to each other. According to some embodiments, the dipole orientation refers to the orientation of a connecting line in between two loudspeakers forming an acoustic dipole. According to some embodiments, this connecting line is not restricted to a specific direction and therefore includes both the connection in between a first loudspeaker and a second loudspeaker and vice versa.
As used herein, the “main radiation direction” of the 3D soundfield generated by the audio device may be defined as an area proximate to which a listener may perceive a preferably high-quality 3D audio experience. According to some embodiments, the main radiation direction may be the direction of the main power output of the soundfield generated by the audio device. According to some embodiments, the main radiation direction may be parallel or at least substantially parallel to the normal vector of the main plane defined by the elliptical torus shape of the housing. According to some further embodiments, the main radiation direction may in the operation position be perpendicular or at least substantially perpendicular to the main plane.
In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that a fourth pair of the plurality of loudspeakers form a fourth dipole for crosstalk cancellation between left hand side signal components and right hand side signal components in the fourth frequency range of the soundfield, wherein a distance between the loudspeakers of the plurality of loudspeakers forming the fourth dipole is smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the second dipole, i.e. the second dipole distance. Hereby, the fourth frequency range may extend to higher frequencies than the second frequency range and a distance between the loudspeakers of the plurality of loudspeakers forming the fourth dipole may be smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the second dipole.
In doing so, the covered frequency range corresponding to the frequency portions of the crosstalk cancellation portions of the soundfield may be increased in certain cases. In particular, this may be the case if the fourth frequency range is not identical with the first frequency range (but may still have a certain overlapping regime).
Alternatively, the signal strength within at least a portion of the first frequency range or within a portion of the second frequency range may also be increased in certain cases. In particular, this may be the case if the first frequency range is at least partially identical with the fourth frequency range.
The distance between the loudspeakers of the plurality of loudspeakers forming the fourth dipole may be identical or at least substantially identical to the distance between the loudspeakers of the plurality of loudspeakers forming the first dipole, i.e. the first dipole distance. The fourth pair of loudspeakers forming the fourth dipole for crosstalk cancellation may be arranged in the elliptical torus shaped housing such that the fourth dipole extends in a parallel or at least substantially parallel displaced orientation to the first and/or second dipole and/or in a perpendicular or at least substantially perpendicular orientation to the third dipole. In the operation position of the audio device, the fourth pair of loudspeakers may form a fourth horizontal or at least substantially horizontal dipole for crosstalk cancellation, which is located parallel or at least substantially parallel to the first and second horizontal or at least substantially horizontal dipole, but at a different vertical height than the first and second horizontal or at least substantially horizontal dipole.
In a further possible implementation form of the first aspect, the processing circuitry is configured to process a first subset of the plurality of input signals to obtain the left hand side signal components, wherein for obtaining the output signals for the first pair of loudspeakers and the second pair of loudspeakers, the processing circuitry is configured to:
As used herein, “bandpass filtering” refers to the signal processing technique of processing an input signal into one or more output signals, wherein the one or more output signals are identical or at least substantially identical to the input signal in one or more selected frequency ranges or bands, but otherwise zero or at least substantially zero. Bandpass filtering may be provided, for instance, using crossover filters providing one or more output signals. According to some implementations, such bandpass filtering means may enable to maintain several frequency ranges (e.g. high frequency range and mid frequency range) at the same time, while setting a remaining frequency range to zero or at least substantially zero. In doing so, a common bandpass filtering unit for maintaining both high frequency ranges and mid frequency ranges may be used.
As used herein, “equalizing” refers to the signal processing technique of equalizing an input signal using an equalization filter, wherein the left and right hand side signal components in the first and second frequency range are filtered to equalize, i.e. flatten the frequency response of the respective first and second dipole. According to some embodiments, first equalizing refers to equalizing input signals using a first equalization filter in a first frequency range. According to some embodiments, second equalizing refers to equalizing input signals using a second equalization filter in a second frequency range. According to some implementations, the first equalization filter and the second equalization filter may be different filters. According to some further implementations, the first equalization filter and the second equalization filter may be unique filters. According to some implementations, first equalizing and second equalizing may be performed by the same equalization filter.
In a further possible implementation form of the first aspect, the processing circuitry is further configured to process the first subset of the plurality of input signals to obtain the right hand side signal components, wherein for obtaining the output signals for the first pair of loudspeakers and the second pair of loudspeakers, the processing circuitry is further configured to:
In a further possible implementation form of the first aspect, for obtaining channel signals, i.e. the left and right hand side signal components, the processing circuitry is further configured to apply a binauralizing based on a convolution of each input signal of the first subset of the plurality of input signals with a first binaural filter and a second binaural filter to obtain a first and a second binaurally filtered version of the respective input signal; and to apply downmixing to generate the left and right hand side signal components based on the first and second binaurally filtered version of each input signal.
Thereby, an improved 3D sound perception may be achieved using preferably simple technical means.
As used herein, “binauralizing” refers to the audio signal processing technique of applying a left ear head-related transfer function (HRTF) filter and a right ear head-related transfer function (HRTF) filter to an input signal. Such HRTF filter capture the transfer path characteristics of sound sources positioned in space and the human ears and may be used to create a virtual 3D sound perception.
According to some embodiments, binauralizing may also be applied within signal processing in order to obtain vertical dipole signals, which may then be used for sound elevation of the soundfield. According to some embodiments, downmixing may also be applied within signal processing in order to obtain vertical dipole signals, which may then be used for sound elevation of the soundfield.
In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that the third pair of the plurality of loudspeakers form the third dipole for sound elevation in a third frequency range of the soundfield and a fifth pair of the plurality of loudspeakers form a fifth dipole for sound elevation in a fifth frequency range of the soundfield, wherein the third frequency range extends to higher frequencies than the fifth frequency range and a distance between the loudspeakers of the plurality of loudspeakers forming the third dipole, i.e. the third dipole distance, is smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the fifth dipole, i.e. the fifth dipole distance. Advantageously, this allows for an even more efficient sound elevation in the third frequency range and the fifth frequency range of the soundfield.
The fifth pair of loudspeakers forming the fifth dipole for sound elevation may be arranged in the elliptical torus shaped housing such that the fifth dipole extends in a parallel or at least substantially parallel displaced orientation to the third dipole and/or in a perpendicular or at least substantially perpendicular orientation to the first and/or second dipole. In the operation position of the audio device, the fifth pair of loudspeakers may form a fifth vertical or at least substantially vertical dipole for sound elevation, which is located parallel or at least substantially parallel to the third vertical or at least substantially vertical dipole.
In a further possible implementation form of the first aspect, the third frequency range may correspond to the first frequency range and/or the fifth frequency range may correspond to the second frequency range. The third frequency range may comprise a high frequency (HF) range and/or the fifth frequency range may comprise a mid frequency (MF) range.
In a further possible implementation form of the first aspect, the plurality of input signals comprise vertical left hand side signal components, wherein for obtaining the output signals for the third pair of loudspeakers and the fifth pair of loudspeakers the processing circuitry is configured to:
In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that the second pair of the plurality of loudspeakers and a further pair of the plurality of loudspeakers form the second dipole, wherein a first loudspeaker of the further pair of loudspeakers is arranged in the housing adjacent to a first loudspeaker of the second pair of loudspeakers and a second loudspeaker of the further pair of loudspeakers is arranged in the housing adjacent to a second loudspeaker of the second pair of loudspeakers. Advantageously, this allows for a more efficient crosstalk cancellation in the second, e.g. MF frequency range.
In a further possible implementation form of the first aspect, the processing circuitry is configured to process the plurality of input signals such that the first loudspeaker of the second pair of loudspeakers and the first loudspeaker of the further pair of loudspeakers form a seventh dipole for sound elevation of the soundfield and/or the second loudspeaker of the second pair of loudspeakers and the second loudspeaker of the further pair of loudspeakers form an eighth dipole for sound elevation of the soundfield.
According to a second aspect, the present disclosure relates to a corresponding method for generating a three-dimensional soundfield using an audio device with a housing having an elliptical torus shape and a plurality of loudspeakers. The method comprises the steps of processing a plurality of input signals to obtain a plurality of output signals and outputting the plurality of output signals to the plurality of loudspeakers. The plurality of input signals are processed such that: a first pair of the plurality of loudspeakers form a first dipole for crosstalk cancellation between left hand side signal components and right hand side signal components in a first frequency range of the soundfield; a second pair of the plurality of loudspeakers form a second dipole for crosstalk cancellation between left hand side signal components and right hand side signal components in a second frequency range of the soundfield; and a third pair of the plurality of loudspeakers form a third dipole for sound elevation of the soundfield. The first frequency range extends to higher frequencies than the second frequency range and a distance between the loudspeakers of the plurality of loudspeakers forming the first dipole, i.e. a first dipole distance, is smaller than a distance between the loudspeakers of the plurality of loudspeakers forming the second dipole, i.e. a second dipole distance.
The second aspect comprises implementation forms which correspond to the implementation forms according to the first aspect.
In a further implementation according to the second aspect, the method may be configured to be executed by an audio device according to any of the embodiments disclosed herein.
According to a third aspect, the present disclosure relates to a computer program product comprising a non-transitory computer-readable storage medium carrying program code which causes a computer or a processor to perform the method according to the second aspect of the present disclosure when the program code is executed by the computer or the processor.
Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.
In the following embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:
a schematically depict an audio device according to an exemplary embodiment of the present disclosure implementing a plurality of horizontal dipoles for crosstalk cancellation and a plurality of vertical dipoles for sound elevation;
In the following identical reference signs refer to identical or at least functionally equivalent features.
In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and a plurality of preferred embodiments according to the present disclosure are defined in the appended claims.
For instance, it is to be understood that a disclosure in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if one or a plurality of specific method steps are described, a corresponding device may include one or a plurality of units, e.g. functional units, to perform the described one or plurality of method steps (e.g. one unit performing the one or plurality of steps, or a plurality of units each performing one or more of the plurality of steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a specific apparatus is described based on one or a plurality of units, e.g. functional units, a corresponding method may include one step to perform the functionality of the one or plurality of units (e.g. one step performing the functionality of the one or plurality of units, or a plurality of steps each performing the functionality of one or more of the plurality of units), even if such one or plurality of steps are not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless specifically noted otherwise.
In the following, some theoretical background will be provided, which will be helpful for understanding specific aspects of exemplary embodiments of the audio device and method according to the present disclosure, before describing some exemplary embodiments of the audio device and method in greater detail.
According to well-established technical background, the simplest audio dipole source consist of two audio point sources (also referred to as “monopoles”) of equal strength operating at the same frequency but vibrating 180 degrees out of phase with each other. In practice, an audio dipole can be obtained by driving two transducers, i.e. loudspeakers with the same signal, but with an inverted phase. Mathematically, an audio dipole can be expressed in the following way. If x(t) denotes the signal for driving the dipole, then y1(t)=x(t) can be the signal for driving the first monopole of the dipole and y2(t)=−x(t) can be the signal for driving the second monopole.
Embodiments of the present disclosure make use of pairs of dipoles working at different frequencies, e.g. at lower and higher frequencies. Such a system can be referred to as a “2 way” dipole system in that the audio frequency is split into two bands (lower and higher), which may be fed to two reproduction systems, i.e. the two dipoles. The crossover frequency, i.e. the frequency splitting the lower and the higher frequency band, can be obtained on the basis of the frequency response by looking for a compromise between beaming and low frequency cancellation (in
Embodiments of the present disclosure make use of the fact that if a delay D is introduced in the signal feeding one of the two dipoles, i.e. y2(t)=−x(t−D), the directivity pattern of the dipole changes (as illustrated in the 360 degree depictions according to
Embodiments of the present disclosure further make use of a dipole for reproducing binaural signals. Binaural signals are generally recorded (or synthesized using head-related transfer function filters) at the eardrums of a listener, and intended to provide accurate spatial sound when reproduced over headphones. If the two binaural signals are denoted as xL(t) and xR(t), a listener using a headphones may perceive xL(t) at his left ear, while he may perceive xR(t) at his right ear. In doing so, an accurate soundfield may be provided to the listener's eardrums, who has the impression to be present in the location where the recording took place.
Reproducing xL and xR with two loudspeakers (not headphones) worsens this experience, the main reason being the fact that xL and xR are now reaching both ears of the listener (which is not what was happening in the recording stage). The leakage of xL into the right ear and of xR into the left ear is called crosstalk, and is desirable to be avoided. In order to enhance binaural reproduction over loudspeakers, crosstalk cancellation may be implemented. Using dipoles is one possibility to implement crosstalk cancellation, which will be described in the following in greater detail in the context of
y
1(t)=xL(t)
y
2(t)=−xL(t−D)
This dipole provides having an intensity to be zero or to be at least substantially zero towards the right ear direction of the listener, so that crosstalk cancellation for the left binaural channel 904 may be achieved. Similarly, a second dipole can be created using the following signals:
y
1(t)=−xR(t−D)
y
2(t)=xR(t).
Such a dipole enables to transmit an intensity to be zero or to be at least substantially zero towards the left ear direction of the listener, so that crosstalk cancellation for the right binaural channel 905 may be achieved. Hereby, an angle Ay defined by the left binaural channel 904 and the right binaural channel 905 may be adapted according to a real or designated distance of a listener 1200 relative to the loudspeakers transmitting the dipole.
Embodiments of the present disclosure make use of the finding that reflections can be used for simulating virtual sources at an elevated height, i.e. for the purpose of “sound elevation”, as e.g. described in U.S. Pat. No. 5,809,150. According to the Haas principle, one requirement that may enable the user to perceive the sound reflection and not the direct sound coming from the source (i.e. the soundbar) is that the reflected sound reaching the user should be at least 10 dB louder than the direct sound. For this purpose, a vertical dipole can be generated and can be used to convey elevated sources content (as illustrated in
Applying an exemplary delay D of 82 microseconds on a dipole 10 cm spaced (i.e. the distance between the two loudspeakers forming the dipole is 10 cm), the pattern shown in
The audio device 900 comprises a housing 901 having an elliptical shape. According to some embodiments, the elliptical shape of the housing 901 may be a circular shape and a the length of a vertical elliptic axis 912a parallel to the z axis and a horizontal elliptic axis 912b parallel to the x axis are equal or at least substantially equal. Hereby, the vertical elliptic axis 912a and the horizontal elliptic axis 912b may be in a range of 3 cm≤912a,912b≤150 cm. According to some embodiments, the vertical elliptic axis 912a and the horizontal elliptic axis 912b may be in a range of 5 cm≤912a,912b≤40 cm. According to some further embodiments, the vertical elliptic axis 912a and the horizontal elliptic axis 912b may be in a range of 10 cm≤912a,912b≤20 cm. The opening regime 914 of the circular shape may be used for accommodating a media device, such as a television, smartphone or tablet computer. This means that a curvature in the upper and lower range of the housing 901 is identical or at least substantially identical to a curvature in the left and right range of the housing 901. Such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive similar dipole distances regarding horizontal dipoles (DH1, DH2, DH3) and vertical dipoles (DV1, DV2, DV3). Therefore, such a geometry may be considered preferable in case that one may achieve similar frequency ranges and frequency range widths in both vertical and horizontal directions.
According to a further embodiment, the elliptical shape of the housing 901 comprises a vertical elliptic axis 912a parallel to the z axis and the vertical elliptic axis 912b parallel to the x axis, wherein the vertical elliptic axis 912a is greater than the horizontal elliptic axis 912b. This means that the curvature in the upper and lower range of the housing 901 is greater than the curvature in the left and right range of the housing 901. Such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive smaller dipole distances regarding horizontal dipoles (DH1, DH2, DH3) compared to vertical dipoles (DV1, DV2, DV3). Accordingly, such a geometry may be considered preferable in case that one may achieve higher frequency ranges in the horizontal direction than in the vertical direction. Further, such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive a smaller variance in dipole distances in between horizontal dipoles (DH1, DH2, Dh3) compared to vertical dipoles (DV1, DV2, DV3). Accordingly, such a geometry may be considered preferable in case that one may achieve greater frequency range widths in the vertical direction than in the horizontal direction.
According to a further embodiment, the elliptical shape of the housing 901 comprises a vertical elliptic axis 912a parallel to the z axis and the horizontal elliptic axis 912b parallel to the x axis, wherein the vertical elliptic axis 912a is smaller than the horizontal elliptic axis 912b. This means that the curvature in the upper and lower range of the housing 901 is smaller than the curvature in the left and right range of the housing 901. Such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive greater dipole distances regarding horizontal dipoles (DH1, DH2, DH3) compared to vertical dipoles (DV1, DV2, DV3). Accordingly, such a geometry may be considered preferable in case that one may achieve lower frequency ranges in the horizontal direction than in the vertical direction. Further, such a geometry facilitates to arrange the loudspeakers in a manner, which enables to receive a higher variance in dipole distances in between horizontal dipoles (DH1, DH2, DH3) compared to vertical dipoles (DV1, DV2, DV3).
The cross sections of the torus shaped housings may in general have any shape. The cross-sections may for example be (at least substantially) circular or elliptical cross sections, square, rectangular, hexagonal or octagonal cross sections.
According to
The audio device 900 may further comprise a processing circuitry 1310 configured to process a plurality of input signals to obtain a plurality of output signals output to the plurality of loudspeakers. The processing circuitry 1310 may, for example, be configured to process a plurality of input signals L, R, UL, UR to obtain a plurality of output signals LCH HF/2, RCH HF/2, LCH MF, RCH MF, UL HF, UR HF, UL MF, UR MF and output the plurality of output signals LCH HF/2, RCH HF/2, LCH MF, RCH MF, UL HF, UR HF, UL MF, UR MF to the plurality of loudspeakers 903a-903h. In order to simplify visualization, however, the processing circuitry has not been depicted in
Moreover, the processing circuitry 1310 of the audio device 900 may be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903c and 903g as a second pair of the plurality of loudspeakers 903a-903h form a second dipole, namely a further horizontal dipole (referred to as dipole horizontal 2 or short “DH2” in
As illustrated in
Moreover, the processing circuitry 1310 of the audio device 900 may be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903f and 903h as a third pair of the plurality of loudspeakers 903a-903h form a third dipole, namely a vertical dipole (referred to as dipole vertical 1 or short “DV1”) for sound elevation 1204a, 1204b of the soundfield (based on the principles described above in the context of
According to a further embodiment, the processing circuitry 1310 may also be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903b and 903d as a sixth pair of the plurality of loudspeakers 903a-903h form a sixth dipole, namely a vertical dipole (referred to as dipole vertical 3 or short “DV3”) for sound elevation 1204a, 1204b of the soundfield. In this case, loudspeaker 903b may be used for two different acoustic dipoles, namely dipoles DH1 and DV3. Thereby, the number of required loudspeakers for achieving the three-dimensional soundfield may be reduced. This may improve compactness of device packaging and may further enable cost saving for the audio device production.
According to a further embodiment, the processing circuitry 1310 may also be configured to process the plurality of input signals L, R, UL, UR such that the loudspeakers 903a and 903e, i.e. a fifth pair of the plurality of loudspeakers 903a-903h form a fifth dipole, namely a vertical dipole (referred to as dipole vertical 2 or short “DV2”) for sound elevation 1204a, 1204b of the soundfield. In this case, none of the loudspeakers will be used for two different acoustic dipoles.
As further illustrated in the embodiment shown in
According to some embodiments, at least some or all of the dipole distances (DD) may be in the range of 5 cm≤DD≤30 cm. According to some embodiments, at least one of the DD of the horizontal dipoles DH1-DH3 is equal or at least substantially equal with one of the DD of the vertical dipoles DV1-DV3. According to some embodiments, the DD of DH1, DH3, DV1 and DV3 may be equal or at least substantially equal. According to some embodiments, the DD of DH2 and DV2 may be equal or at least substantially equal.
As can be further deduced from
According to some embodiments, at least one or several or even all of the dipole orientation angles η1-η8 may be in a range of 65°≤ηi≤115°. According to some embodiments at least one or several or even all of the dipole orientation angles η1-η8 may be in a range of 75°≤ηi≤105°. According to some embodiments at least one or several or even all of the dipole orientation angles η1-η8 may be in a range of 85°≤ηi≤95°. According to some embodiments, the first, second and fourth dipole orientations 907a, 907b, 907d corresponding to dipoles DH1-DH3 are identical or at least substantially identical. According to some embodiments, the third, fifth and sixth dipole orientations 907c, 907e, 907f corresponding to dipoles DV1-DV3 are identical or at least substantially identical. According to some embodiments, first, second and fourth dipole orientations 907a, 907b, 907d corresponding to dipoles DH1-DH3 are perpendicular or at least substantially perpendicular to third, fifth and sixth dipole orientations 907c, 907e, 907f corresponding to dipoles DV1-DV3.
Additionally or alternatively to the horizontal dipoles DH1-D3 and the vertical dipoles DV1-DV3 depicted in
Additionally or alternatively, the audio device 900 may comprise further substantially vertical dipoles (not depicted in
Additionally or alternatively, the audio device 900 may comprise further substantially vertical dipoles (not depicted in
Alternatively to the configuration of
Moreover, as illustrated in the embodiment shown in
As can be taken from the embodiment shown in
Although the embodiment shown in
In addition, although the embodiment shown in
According to further embodiments, the audio device 900 may be configured to reproduce multichannel content which involves elevated sources similar to the multichannel audio format 7.1.2. In an embodiment, the audio device 900 may be configured to handle the following channels-based input of the multichannel audio format 7.1.2 as follows: the horizontal input signals L, R, C, SL, SR, SBL, SBR (C represents an input signal input by a centered channel, SL represents an input signals input by the surround or front left channel, SR represents an input signal input by the surround or front right channel, SBL represents in input signal input by the surround back or rear left channel and SBR represents an input signal input by the surround back or rear right channel); and the vertical left and right hand signal components: UL, UR. According to some implementations, there may also be a reduced number of horizontal input signals. As an example, the horizontal input signals may also be restricted to L and R.
In a first processing stage, these horizontal signals may be “binauralized”, i.e. convolved with binaural filters (Head Related Transfer Functions) in order to obtain binaural signals corresponding to the horizontal loudspeakers 903a-903h in the 7.1.2 setup (see “binauralization” block 1301 in
As can be taken from
According to the embodiment illustrated in
The effect of the full processing chain for the horizontal components implemented by the processing circuitry 1310 of the audio device 900 according to an embodiment and shown in
A portion 1304 of the full processing chain for the horizontal components is illustrated in more detail in
Moreover, the processing circuitry 1310 of the audio device 900 may be configured to apply a bandpass filtering to the right hand side signal components RCH provided by the downmix unit 1303. Hereby, the crossover unit 1305b is used to obtain right hand side signal components RCH HF/2 in the first frequency range HF and right hand side signal components RCH MF in the second frequency range MF. Optionally, the crossover unit 1305a may be also used to obtain right hand side signal components RCH LF in a first frequency range LF. Moreover, the processing circuitry 1310 of the audio device 900 may be configured to implement a third dipole processing unit 1307b for generating further components of the output signals for feeding the loudspeakers 903b, 903d, 903f, 903h of the first and fourth dipole DH1 and DH3 and to implement a fourth dipole processing unit 1309b for generating further components of the output signals for feeding the loudspeakers 903c, 903g of the second horizontal dipole DH2.
A possible implementation of the first dipole processing unit 1307a for generating components of the output signals for feeding the loudspeakers 903b, 903d, 903f, 903h of the first and fourth dipole DH1 and DH3 is shown in
According to a first processing branch 1404a of the first dipole processing unit 1307a shown in
According to some further implementations, the first dipole processing unit 1307a may also comprise the equalization filter 1403, the inverter unit 1403 and the delay unit 1405, however, the ordering of these elements may be modified. The same also applies to further implementations of the second dipole processing unit 1309a, the third dipole processing unit 1307b and the fourth dipole processing unit 1309b.
According to some further implementations, the first processing branch 1404a and the second processing branch 1404b of the first dipole processing unit 1307a may be interchanged with each other. In this case, the corresponding directional dipole response is different from
As can be deduced from
As can be taken from
The LF band limited right channel or left channel signals can be directly output to a subset of the plurality of loudspeakers 903a-903h, such as the loudspeakers 903f and 903h and/or 903b and 903d, or even to all loudspeakers 903a-903h.
As can be taken from
According to an embodiment, the processing circuitry 1310 of the audio device 900 is configured to generate the output signals for driving the loudspeakers 903a and 903e of the fifth dipole DV2 (having a larger dipole distance than the third and sixth dipole DV1 and DV3) in the following way. A first, e.g. elevated, component of the output signal for the loudspeaker 903a is provided as the output signal at the plus-phased (+) output of the dipole processing unit 1505a, which is based on the vertical left hand side signal component UL MF in the second frequency range MF. A second, e.g. deepened, component of the output signal for the loudspeaker 903a is provided as the output signal at the minus-phased (−) output of the dipole processing unit 1505b, which is based on the vertical right hand side signal component UR MF in the second frequency range MF. Likewise, a first component of the output signal for the loudspeaker 903e is provided as the output signal at the minus-phased (−) output of the dipole processing unit 1505a, which is based on the vertical left hand side signal component UL MF in the second frequency range MF. The second component of the output signal for the loudspeaker 903e is provided as the output signal at the plus-phased (+) output of the dipole processing unit 1505b, which is based on the vertical right hand side signal component UR MF in the second frequency range MF.
As further illustrated in
As in the case of the horizontal dipoles, the LF band limited signals, i.e. UL LF and UR LF, can be directly output to a subset of the plurality of loudspeakers 903a-903h, such as the loudspeakers 903f and 903h and/or 903b and 903d, or even to all loudspeakers 903a-903h.
In a modification of the embodiment shown in
The person skilled in the art will understand that the “blocks” (“units”) of the various figures (method and apparatus) represent or describe functionalities of embodiments of the present disclosure (rather than necessarily individual “units” in hardware or software) and thus describe equally functions or features of apparatus embodiments as well as method embodiments (unit=step).
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the described apparatus embodiment is merely exemplary. For example, the unit division is merely logical function division and may be other division in actual implementation. For example, a plurality of units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented by using some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in electronic, mechanical, or other forms.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
In addition, functional units in the embodiments of the present disclosure may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit.
This application is a continuation of International Application No. PCT/EP2019/086757, filed on Dec. 20, 2019, the disclosure of which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2019/086757 | Dec 2019 | US |
| Child | 17845616 | US |
