A method and system for realizing sound field movement based on multi-channel parametric array loudspeaker

Abstract

The present invention discloses a method and system for achieving sound field movement based on a multi-channel parametric array speaker, wherein the parametric array speaker includes an ultrasonic transducer array, the ultrasonic transducer array includes multiple sound channels spaced along a first direction, and each sound channel includes at least one ultrasonic transducer. During operation, by identifying the position information of a target object, an excitation weight matrix is called according to the position information to obtain a set of excitation weights corresponding to the position information. By assigning the set of excitation weights to the sound channels of the parametric array speaker, some of the sound channels in the parametric array speaker are directed to the position of the target object to emit sound; different position information corresponds to different excitation weights, and sound field movement is achieved by assigning different excitation weights to the parametric array speaker. The present invention saves time and labor and also greatly improves the efficiency of achieving sound field movement by the parametric array speaker.

Description

Technical Field

[0001] The present invention relates to the technical field of directional sound generation, and in particular to a method and system for realizing sound field movement based on a multi-channel parametric array loudspeaker. Background Art

[0002] A parametric array loudspeaker is an acoustic system that uses the nonlinear acoustic effect of a medium to generate directional sound waves. The difference frequency audible sound (frequencies f1 to f2) is generated by the nonlinear self-demodulation of finite amplitude ultrasound (frequencies f1 and f2) through air.

[0003] During the forward transmission process, the ultrasonic frequencies f1 and f2 will be demodulated differently to produce virtual audible sound sources with cumulative effects at frequencies f1 to f2, forming a situation similar to an end-fire array speaker, thereby achieving a highly directional audible sound beam and an ultra-long audible sound propagation distance.

[0004] In order to achieve sound field movement or directional deflection, parametric array speakers are used in functions such as head tracking. Signal processing is usually used to adjust the phase of each channel. Phase adjustment is mainly achieved using delay to compensate for the sound path difference from each channel to the directional sound emission position.

[0005] Using multi-channel signal processing to adjust the phase of each channel requires that the spacing between channels be controlled to be less than the wavelength corresponding to the ultrasonic frequency, otherwise sidelobes will appear in the sound field. For example, an ultrasonic frequency of 40kHz corresponds to a sound wave wavelength of approximately 8.6mm, and a 0.2m wide ultrasonic transducer array requires at least 24 channels. For example, an ultrasonic frequency of 80kHz corresponds to a sound wave wavelength of approximately 4.3mm, and a 0.2m wide ultrasonic transducer array requires at least 47 channels. Therefore, using multi-channel signal processing to adjust the phase of each channel requires a large number of channels, which will increase system complexity and cost.

[0006] Alternatively, multi-channel parametric speakers can be used to achieve sound field movement. This is achieved by controlling channel signals, including by controlling whether each channel is active. However, the accuracy of sound field movement in this solution is determined by the width of a single channel, resulting in limited head positioning accuracy in functions such as head tracking. Since accuracy can only be improved by reducing channel width, the number of channels would increase significantly.

[0007] Alternatively, the number of required sound channels can be reduced by calibrating the excitation signal weights of the sound channels, thereby reducing costs and power consumption. However, the existing method of calibrating the excitation signal weights of the sound channels through experiments usually requires a lot of preliminary work, consumes manpower and material resources, and is inefficient.

[0008] Therefore, it is necessary to improve the prior art to overcome the above defects. Summary of the Invention

[0009] The object of the present invention is to provide a method and system for achieving sound field movement based on a multi-channel parametric array loudspeaker, which saves time and effort and greatly improves the efficiency of the loudspeaker in achieving sound field movement.

[0010] In order to solve the above technical problems, in a first aspect, the present invention proposes a method for achieving sound field movement based on a multi-channel parametric array loudspeaker, wherein the parametric array loudspeaker includes an ultrasonic transducer array, the ultrasonic transducer array includes a plurality of sound channels spaced apart along a first direction, each of the sound channels includes at least one ultrasonic transducer, and each of the sound channels is independently controlled. The method includes:

[0011] Identify the position information of the target object, call the excitation weight matrix according to the position information, obtain a set of excitation weights corresponding to the position information, and assign the set of excitation weights to the sound channels of the parametric array speaker so that some of the sound channels in the parametric array speaker are aligned with the position of the target object to emit sound in a direction; different position information corresponds to different excitation weights, and the sound field is moved by assigning different excitation weights to the parametric array speaker;

[0012] The process of obtaining the incentive weight matrix includes:

[0013] According to the radiation sound pressure p(x+(n-1)l) of each sound channel and the set excitation weights [α 1m ,α 2m ,…,α nm ], and the total sound field p radiated by the parametric array loudspeaker is obtained T (x);

[0014] According to the maximum value p of the total sound field Tmax , get the position information x corresponding to the maximum value m , by the position information x m and incentive weight [α 1m ,α 2m ,…,α nm ] The incentive weight matrix is expressed as:

[0015]

[0016] Among them, n is the number of sound channels, l is the distance between the sound channels, m is the number of sound field movement positions, n and m are both integers greater than or equal to 2, and x is the sound field movement position.

[0017] As an advantage, the total sound field p T (x) is expressed as:

[0018] pT (x) = α 1m p(x)+α 2m p(x+l)+…+α nm p(x+(n-1)l).

[0019] Preferably, if the ultrasonic transducer array is divided into left and right channels, the left position information and right position information corresponding to the left and right channels are determined according to the position information of the target object, and a set of excitation weights are determined according to the left position information and the right position information.

[0020] Preferably, the accuracy of the sound field movement is smaller than the width of a single sound emission channel in the first direction.

[0021] Preferably, during the movement of the target object, the sound channels at different positions are homogenized so that the sound pressure at different positions is the same.

[0022] Preferably, the homogenization process includes adjusting the excitation voltage of the sound channel.

[0023] Preferably, the remaining sound emission channels except for some sound emission channels corresponding to the position information are controlled to emit low-frequency signals for low-frequency compensation of the sound field, and the low-frequency signals are signals below 1 kHz.

[0024] Preferably, the plurality of sound channels spaced apart along the first direction form a sound channel group, and the ultrasonic transducer array includes one or more sound channel groups arranged along one or more second directions.

[0025] Preferably, the distance between two adjacent sound emission channels and the distance between two adjacent sound emission channel groups are both 1 mm to 100 mm.

[0026] In a second aspect, the present invention further proposes a system for achieving sound field movement based on a multi-channel parametric array loudspeaker, comprising:

[0027] An excitation weight matrix acquisition module is used to obtain the total sound field radiated by the parametric array speaker based on a set of excitation weights corresponding to the radiated sound pressure of each sound channel and each set sound field movement position, obtain the position information corresponding to the maximum value of the total sound field based on the maximum value, and obtain the excitation weight matrix from the position information and the excitation weights;

[0028] A location recognition module is used to identify the location information of the target object;

[0029] The sound field movement module is connected to the excitation weight matrix acquisition module, the position identification module and the parametric array speaker as described above, and is used to call the excitation weight matrix according to the position information to obtain a set of excitation weights corresponding to the position information, and assign this set of excitation weights to the sound channels of the parametric array speaker so that some of the sound channels in the parametric array speaker are aligned with the position of the target object and emit sound in a direction; different position information corresponds to different excitation weights, and sound field movement is achieved by assigning different excitation weights to the parametric array speaker.

[0030] Preferably, the system further comprises: a sound field homogenization module, connected to the sound field movement module and the parametric array speaker, for homogenizing the sound channels at different positions during the movement of the target object, so that the sound pressure at different positions is the same.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The present invention utilizes the principle of sound field superposition to pre-derive the excitation weight matrix for the sound channel. During operation, the excitation weight matrix is directly called based on position information to obtain the excitation weights corresponding to the position information. By assigning this set of excitation weights to the sound channels of the parametric array speaker, some of the sound channels in the parametric array speaker are directed toward the target object and emit sound. Different excitation weights are called based on different position information, and sound field movement is achieved by assigning different excitation weights to the parametric array speaker. Compared to existing solutions that calibrate the excitation weights of sound channels through experiments, the present invention saves time and effort and greatly improves the efficiency of the speaker in achieving sound field movement.

[0033] 2. The parametric array loudspeaker of the present invention divides the ultrasonic transducer array into multiple, spaced-apart sound channels. Each channel includes at least one ultrasonic transducer, and each channel is independently controlled. By varying the excitation signal weights of the channels corresponding to the target object's position, high-precision movement of the sound field is achieved, enabling applications such as head tracking. Furthermore, the present invention can achieve high-precision movement of the sound field with fewer channels, thereby reducing system complexity and cost.

[0034] 3. The present invention performs homogenization on the sound channel during the movement of the target object, so that the sound pressure received by the human head at different positions is equal, reducing the difference in the hearing perception of the sound receiver during the movement and improving the auditory effect.

[0035] 4. The present invention controls the radiation of low-frequency waves from the remaining sound channels except for the directionally directed sound to the target object, thereby achieving high-precision movement of the sound field and increasing the sound pressure of the low-frequency part of the sound field. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only schematic and are used to help understand the present invention, and do not specifically limit the shapes and proportional dimensions of the components of the present invention. Those skilled in the art can select various possible shapes and proportional dimensions to implement the present invention according to the specific circumstances under the guidance of the present invention. In the drawings:

[0037] Figure 1 It is a technical principle diagram of a parametric array loudspeaker in the prior art;

[0038] Figure 2 This is a schematic diagram of the principle of high directivity directional propagation of a parametric array loudspeaker in the prior art;

[0039] Figure 3 This is a structural diagram of a parametric array loudspeaker in the present invention;

[0040] Figure 4 This is a schematic diagram of a structure for applying excitation signal weights to an embodiment of a parametric array loudspeaker in the present invention;

[0041] Figure 5 2 is a schematic diagram of a structure for applying excitation signal weights in another embodiment of a parametric array loudspeaker according to the present invention;

[0042] Figure 6 It is a structural diagram of an existing parametric array loudspeaker that realizes sound field movement without adding excitation signal weight;

[0043] Figure 7 It is a structural schematic diagram of an embodiment of a parametric array loudspeaker of the present invention;

[0044] Figure 8 This is a structural diagram of an embodiment of a parametric array loudspeaker (divided into left and right channels) of the present invention;

[0045] Figure 9 It is a structural diagram of the parametric array loudspeaker for bass compensation in the present invention;

[0046] Figure 10 Schematic diagram of the frequency response curve of the parametric array loudspeaker before and after low-frequency compensation of the present invention;

[0047] Figure 11 Schematic diagram of the structure of another embodiment of the parametric array loudspeaker of the present invention;

[0048] Figure 12 It is a schematic diagram of the principle block diagram of the sound field movement system of the present invention. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0050] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be an element centered thereon. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an element centered thereon. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] like Figure 3 As shown, a parametric array loudspeaker corresponding to a preferred embodiment of the present invention includes an ultrasonic transducer array, which includes a plurality of sound emission channels 1 spaced apart along a first direction, each sound emission channel 1 includes at least one ultrasonic transducer 2, and the ultrasonic transducer 2 is used to emit directional sound, and each sound emission channel 1 independently controls the sound emission. Figure 4 and Figure 5 As shown, during operation, according to the position information of the target object, corresponding excitation signal weights are applied to the part of the sound emission channels 1 corresponding to the position information in the ultrasonic transducer array, so that the part of the sound emission channels 1 are aligned with the position of the target object and emit sound in a direction.

[0053] During implementation, each position information corresponds to at least a portion of the continuously spaced sound channels covering the target object, and different excitation signal weights are applied to the partially continuously spaced sound channels. The partially continuously spaced sound channels then emit directionally sound to targets at different positions, thereby achieving sound field movement. Figure 4As shown, for example, a parametric array loudspeaker with 8 sound channels of 640mm×300mm in size, the sound channels covering the target object are the fourth sound channel N4 and the fifth sound channel N5, which are arranged continuously at intervals. For the convenience of description, the fourth sound channel and the fifth sound channel are represented by N4 and N5 respectively, and different excitation signal weights are applied to the sound channels N4 and N5, so that the sound channels N4 and N5 can achieve directional sound at different positions. For example, the sound field radiated by these two sound channels N4 and N5 has three sound field movement positions from left to right, which are defined as position 1, position 2 and position 3 respectively, and the excitation signal weights applied to the sound channels N4 and N5 are represented as weights W1 and W2 respectively. As shown in Table 1 below, the weights W1 and W2 of the sound channels N4 and N5 corresponding to different positions are configured.

[0054] Location W1 W2 1 0.75 0.25 2 0.5 0.5 3 0 1

[0055] Table 1

[0056] That is, if the target object is at position 1, the excitation signal weights W1 and W2 of the sound channels N4 and N5 are configured to be 0.75 and 0.25 respectively; if the target object is at position 2, the excitation signal weights W1 and W2 of the sound channels N4 and N5 are configured to be 0.5 and 0.5 respectively; if the target object is at position 3, the excitation signal weights W1 and W2 of the sound channels N4 and N5 are configured to be 0 and 1 respectively. In other words, by applying different excitation signal weights to the sound channels corresponding to the target object positions, the sound field can be moved to multiple positions, such as from position 1 to position 3.

[0057] If no excitation signal weight is applied to the sound channels N4 and N5, the sound field position formed by them is generally at the center of the two sound channels, that is, there is only one directional sound position, and the sound pressure level at this position is the largest. Figure 6 It is a 16-channel existing parametric array loudspeaker with a size of 640mm×300mm. The loudspeaker realizes sound field movement by controlling whether the channel sounds. Therefore, the accuracy of its moving sound field is the width of a single sound channel in the first direction, that is, the minimum accuracy of the sound field movement is the width of a single sound channel. Therefore, the loudspeaker can realize sound field movement in 15 positions. Figure 6 The figure shows the sound field distribution achieved by controlling whether the channel emits sound when the head is in different positions. By applying different excitation signal weights to each sound channel, the sound field can be moved to multiple positions as needed. For example, it is not limited to the three positions shown here, and can be more than three positions. In this way, the accuracy of the sound field movement will be higher. Figure 5The parametric array loudspeaker shown in the figure achieves sound field movement by controlling the excitation signal weights of some sound channels, and the movement accuracy of the sound field is less than the width of a single sound channel in the first direction. If the sound field moves with an accuracy of half the width of the sound channel, under the same size (640mm×300mm), the above Figure 6 The same amount of sound field movement in the existing only requires 8 sound channels. Figure 5 The figure shows the sound field distribution achieved by controlling the excitation weights of the channels when the head is in different positions. Therefore, the present invention can effectively reduce the number of channels required by moving the sound field with high precision.

[0058] Unlike the existing method of obtaining the excitation signal weights of the sound channel through experimental calibration, the excitation signal weights of the sound channel corresponding to different sound field movement positions in the present invention are preferably obtained by calling a pre-calculated excitation weight matrix. Specifically, the process of obtaining the excitation weight matrix includes:

[0059] According to the radiation sound pressure p(x+(n-1)l) of each sound channel and the set excitation weights [α 1m ,α 2m ,…,α nm ], and the total sound field p radiated by the parametric array loudspeaker is obtained T (x). Wherein, the total sound field p T (x) can be expressed as:

[0060] p T (x) = α 1m p(x)+α 2m p(x+l)+…+α nm p(x+(n-1)l).

[0061] According to the maximum value p of the total sound field Tmax , get the position information x corresponding to the maximum value m , by the position information x m and incentive weight [α 1m ,α 2m ,…,α nm ] The incentive weight matrix is expressed as:

[0062]

[0063] Where n is the number of sound channels, l is the distance between the sound channels, m is the number of sound field movement positions, n and m are both integers greater than or equal to 2, α 1m ,α 2m ,…,α nm The excitation weight applied to each vocal channel.

[0064] Theoretically, the radiated sound pressure of each sound channel should be the same, that is, p(x) = p(x+l) = ... = p(x+(n-1)l). In practice, p(x) can be solved theoretically or measured experimentally. For example, a set of excitation matrices [α 10 ,α 20 ,…,α n0 ], between p(x) and [α 10 ,α 20 ,…,α n0 ] is known, the total sound field p can be T The total sound field p at the sound field moving position is obtained by the formula (x) T (x), because p T (x) is a function of the sound field movement position x, so its maximum value p can be calculated Tmax , record the maximum value p Tmax The corresponding position is x0, that is, a set of position information and excitation matrices can be obtained, namely [x0, α 10 ,α 20 ,…,α n0 ], and so on, the matrix of m position information and excitation can be calculated, and finally the above-mentioned excitation weight matrix can be obtained.

[0065] Taking a specific embodiment as an example, Figure 7 As shown, there are a total of 8 sound channels in the parametric array loudspeaker. The width of each sound channel is 75mm, and the distance between two adjacent sound channels is also 75mm. The total length of the loudspeaker is 600mm and the width is 300mm. The sound field movement is achieved by sounding through 4 to 5 sound channels. The center point between sound channel 4 and sound channel 5 is taken as the coordinate origin, and 17 sound field movement positions are set, namely x = [0, ±18.75, ±37.5, ±56.25, ±75, ±93.75, ±112.5, ±131.25, ±150], that is, the sound field is moved with 1 / 4 channel width. In other words, for the parametric array loudspeaker mentioned in this embodiment, the sound field movement of 17 positions can be achieved. According to the acquisition process of the above-mentioned excitation weight matrix, the excitation weights of each sound channel at these 17 different positions and the total excitation voltage at each position can be solved as shown in Table 2 below:

[0066] Position mm Channel 1 Channel 2 Channel 3 Channel 4 Channel 5 Channel 6 Channel 7 Channel 8 Total voltage 0 0 0 1 1 1 1 0 0 4 18.75 0 0 1 1 1 1 0.5 0 4.5 37.5 0 0 1 1 1 1 1 0 5 56.25 0 0 0.5 1 1 1 1 0 4.5 75 0 0 0 1 1 1 1 0 4 93.75 0 0 0 1 1 1 1 0.5 4.5 112.5 0 0 0 1 1 1 1 1 5 131.25 0 0 0 0.5 1 1 1 1 4.5 150 0 0 0 0 1 1 1 1 4 -18.75 0 0.5 1 1 1 1 0 0 4 -37.5 0 1 1 1 1 1 0 0 5 -56.25 0 1 1 1 1 0.5 0 0 4.5 -75 0 1 1 1 1 0 0 0 4 -93.75 0.5 1 1 1 1 0 0 0 4.5 -112.5 1 1 1 1 1 0 0 0 5 -131.25 1 1 1 1 0.5 0 0 0 4.5 -150 1 1 1 1 0 0 0 0 4

[0067] Table 2

[0068] In addition, preferably, during the movement of the target object, in order to reduce the difference in hearing perception of the sound receiver at different positions, it is preferred to perform homogenization processing on the sound channels at different sound field movement positions so that the sound pressure at different sound field movement positions is the same. During implementation, the excitation voltage of the sound channel is specifically adjusted. Specifically, the principle of homogenization is: there is a positive correlation between the total sound pressure level of the sound pressure radiated by the sound channel and the excitation voltage of the sound channel. Therefore, by controlling the excitation voltage of the sound channel, it can be achieved that the sound pressure of the sound received by the target object remains unchanged during the movement of the sound field, thereby ensuring the user's hearing perception. After the homogenization process, Table 2 above will be updated to Table 3 below:

[0069] Position mm Channel 1 Channel 2 Channel 3 Channel 4 Channel 5 Channel 6 Channel 7 Channel 8 Total voltage 0 0.00 0.00 1.00 1.00 1.00 1.00 0.00 0.00 4 18.75 0.00 0.00 0.89 0.89 0.89 0.89 0.44 0.00 4 37.5 0.00 0.00 0.80 0.80 0.80 0.80 0.80 0.00 4 56.25 0.00 0.00 0.44 0.89 0.89 0.89 0.89 0.00 4 75 0.00 0.00 0.00 1.00 1.00 1.00 1.00 0.00 4 93.75 0.00 0.00 0.00 0.89 0.89 0.89 0.89 0.44 4 112.5 0.00 0.00 0.00 0.80 0.80 0.80 0.80 0.80 4 131.25 0.00 0.00 0.00 0.44 0.89 0.89 0.89 0.89 4 150 0.00 0.00 0.00 0.00 1.00 1.00 1.00 1.00 4 -18.75 0.00 0.44 0.44 0.89 0.89 0.89 0.00 0.00 4 -37.5 0.00 0.80 0.80 0.80 0.80 0.80 0.00 0.00 4 -56.25 0.00 0.89 0.89 0.89 0.89 0.44 0.00 0.00 4 -75 0.00 1.00 1.00 1.00 1.00 0.00 0.00 0.00 4 -93.75 0.44 0.89 0.89 0.89 0.89 0.00 0.00 0.00 4 -112.5 0.80 0.80 0.80 0.80 0.80 0.00 0.00 0.00 4 -131.25 0.89 0.89 0.89 0.89 0.44 0.00 0.00 0.00 4 -150 1.00 1.00 1.00 1.00 0.00 0.00 0.00 0.00 4

[0070] Table 3

[0071] Preferably, the present invention is also applicable to the sound field movement of the left and right channels. Specifically, if the ultrasonic transducer array is divided into left and right channels, the left position information and right position information corresponding to the left and right channels are determined according to the position information of the target object, and a set of excitation weights are determined according to the left position information and the right position information.

[0072] Taking the parametric array loudspeaker with 8 sound channels as an example, if the distance between the left and right channels is 150 mm, which is exactly the distance between the two sound channels, the following table 4 can be obtained according to the above method:

[0073]

[0074] Table 4

[0075] For example, if the target is at -150mm, Figure 8 The left and right channel sound field diagram is shown in Figure 1. The left and right channel position information should be at -225mm and -75mm respectively. Figure 8 As shown, channels 1, 2, 3, and 4 sound, and according to the left position information and the right position information, the excitation weights of these four sound channels are determined to be 1:1:1:1. The superimposed sound field at this time is as follows Figure 8 shown.

[0076] If the distance between the left and right channels is 180 mm, which is greater than the distance between the two sound channels, the following excitation weight table (Table 5) can be obtained according to the above method:

[0077]

[0078] Table 5

[0079] In addition, preferably, in addition to controlling the normal audio signals of some sound emission channels corresponding to the position information, the remaining sound emission channels can also be controlled to emit low-frequency signals for low-frequency compensation of the sound field. In implementation, the low-frequency signal can specifically be a signal below 1KHz. In implementation, if Figure 9 As shown in the figure, the normal sound channel is connected to the audio signal, and the remaining low-frequency compensation channels are connected to the audio signal through a low-pass filter. The audio signal is directly input to the normal sound channel for directional output. At the same time, the audio signal is filtered by the low-pass filter and outputs a low-frequency signal below 1kHz to the low-frequency compensation channel, which is output by the low-frequency compensation channel to form a moving sound field while performing low-frequency compensation on the sound field, thereby effectively making up for the low-frequency deficiency of the parametric array speaker.

[0080] like Figure 10 Figure 2 shows a schematic diagram of the frequency response curves of a parametric array loudspeaker before and after low-frequency compensation in a specific embodiment. This embodiment features an 8-channel, 640mm x 300mm parametric array loudspeaker. Two of the channels are normal sound channels, enabling sound field movement, while the remaining six channels are low-frequency compensation channels. Before low-frequency compensation, the parametric array loudspeaker attenuates at a rate of 12dB / oct below 1kHz. The low-frequency compensation channels boost the sound pressure level below 1kHz by approximately 6dB, thus compensating for the parametric array loudspeaker's limited low-frequency radiation.

[0081] like Figure 3 As shown, there is a certain distance l between the centers of two adjacent sound channels 1, and the distance l is adapted to the moving accuracy of the moving sound field. For example, if the accuracy is high, the number of sound channels will increase accordingly, thereby reducing the distance between the sound channels, and vice versa. The theoretical basis for setting the distance between the sound channels is that the distance between each sound channel is controlled to be less than the wavelength corresponding to the ultrasonic frequency. Preferably, the distance l between the centers of two adjacent sound channels 1 is set between 1mm and 100mm. It should be explained that the distance between two adjacent sound channels 1 here is Figure 2 The distance between the longitudinal center axes of the two sound channels 1.

[0082] Furthermore, a plurality of sound channels 1 arranged along the second direction are defined to form a sound channel group 3, such as Figure 11As shown, the ultrasonic transducer array also includes one or more sound channel groups 3 arranged along one or more second directions, and the number and direction of the second directions are not limited. Preferably, the number of the second directions is one, and the second direction is arranged perpendicular to the first direction, so that the sound channels in one or more sound channel groups 3 can be arranged in a square array in the direction of the X-axis and the Y-axis, so that the sound field can move more evenly. Of course, a reference point can also be selected in the first direction, the reference point and the first direction form a first reference line, the reference point and the second direction form a second reference line, and the angle between the first reference line and the second reference line is 0° to 360°, so that an irregular arrangement of sound channels can be formed to adapt to different application scenarios. Accordingly, the spacing between the centers of two adjacent sound channel groups 3 is also adapted to the movement accuracy of the moving sound field. The reason can be seen in the spacing l between the centers of two adjacent sound channels 1, which will not be further elaborated here.

[0083] There is no restriction on the arrangement of the ultrasonic transducers 2 in the ultrasonic transducer array. It can be arranged in a conventional square array or a circular array, or it can be arranged in an irregular shape. Different arrangements adapt to different sound channel 1 arrangement scenarios, making the parametric array speaker more flexible. The number of sound channels 1 in each sound channel group 3 is adapted to the size of the ultrasonic transducer array in that direction and the movement accuracy of the moving sound field. For example: the ultrasonic frequency is 40kHz, the required movement accuracy of the moving sound field is 20mm, and the width of the ultrasonic transducer array in that direction is 0.2m. Then the number of sound channels required is at least 10. Compared with the at least 24 channels required by the prior art method of using multi-channel signal processing to adjust the phase of each channel, the number of sound channels is greatly reduced, thereby effectively reducing the system complexity and cost. Accordingly, the size of the ultrasonic transducer array in any direction is adapted to the movement accuracy and sound pressure level requirements of the moving sound field. Typically, the size of the ultrasonic transducer array is between 0.1m and 0.5m.

[0084] Correspondingly, such as Figure 12 As shown, the present invention also proposes a system for achieving sound field movement based on a multi-channel parametric array speaker, which can be applied, for example, in scenarios such as precise head tracking, including:

[0085] The excitation weight matrix acquisition module 4 is used to obtain the total sound field radiated by the parametric array speaker 7 based on a set of excitation weights corresponding to the radiated sound pressure of each sound channel and each set sound field movement position, and obtain the position information corresponding to the maximum value of the total sound field, and obtain the excitation weight matrix from the position information and the excitation weight; wherein, how to obtain the excitation weight matrix specifically can refer to the description in the above method, which will not be further elaborated here.

[0086] Position identification module 5, used to identify the location information of the target object;

[0087] The sound field movement module 6 is connected to the excitation weight matrix acquisition module 4, the position identification module 5 and the above-mentioned parametric array speaker 7, and is used to call the excitation weight matrix according to the position information to obtain a set of excitation weights corresponding to the position information, and assign this set of excitation weights to the sound channels of the parametric array speaker 7, so that some of the sound channels in the parametric array speaker 7 are aligned with the position of the target object and emit sound in a direction; different position information corresponds to different excitation weights, and sound field movement is achieved by assigning different excitation weights to the parametric array speaker 7.

[0088] Preferably, the system may further include a sound field homogenization module (not shown), connected to both the sound field movement module 6 and the parametric array speaker 7, for homogenizing the sound channels at different locations during the movement of the target object, thereby ensuring that the sound pressure at different locations is uniform. The specific method for performing the homogenization process can be found in the description of the parametric array speaker 7 and will not be further elaborated here.

[0089] like Figure 4 and Figure 5 As shown, taking the head tracking scenario as an example, a camera or ultrasonic positioning technology is usually used to identify the position of the head, and the position of the head is transmitted to the sound field movement module 6. By calling the excitation weight matrix according to the position of the head, a set of excitation weights corresponding to the position of the head is obtained. By assigning this set of excitation weights to the sound channels of the parametric array speaker 7, some of the sound channels in the parametric array speaker 7 are aligned with the position of the target object and make directionally sound. When the target object moves, the position recognition module 5 updates the target object position in real time, and the sound field movement module 6 calls the excitation weight matrix in real time to update the excitation signal weight. At the same time, the sound field uniformization module adjusts the excitation voltage of the corresponding sound channel, so that the sound field moves and is aligned with the target object while making the sound pressure at different positions consistent.

[0090] During implementation, the distance between the parametric array speaker 7 and the target object (such as a human head) is preferably between 0.5m and 3m, so that the sound emitted by the parametric array speaker 7 can be better received by the human, and the width of the sound channel 1 is preferably adapted to the width of the human head, so as to reduce interference with other areas and provide point-to-point reminders. Furthermore, preferably, the width of the entire parametric array speaker 7 is 300mm, the total number of sound channels 1 is 16, and the distance between two adjacent sound channels 1 is between 10mm and 100mm, which can better control costs, obtain a better sound pressure level, and have better sound field movement accuracy.

[0091] Preferably, the system may further include a bass compensation module (not shown), which is connected to the remaining sound channels of the parametric array loudspeaker, excluding the sound channels corresponding to the position information, and is used to provide a low-frequency signal for low-frequency compensation of the sound field. The specific low-frequency compensation method can also be referred to the description of the parametric array loudspeaker above and will not be further elaborated here.

[0092] It should be understood that the above description is for illustrative purposes only and is not intended to be limiting. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of completeness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the preceding claims is not a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A method for achieving sound field movement based on a multi-channel parametric array speaker, wherein the parametric array speaker includes an ultrasonic transducer array, the ultrasonic transducer array includes a plurality of sound channels spaced apart along a first direction, each of the sound channels includes at least one ultrasonic transducer, and each of the sound channels is independently controlled, characterized in that: The method comprises: Identify the position information of the target object, call the excitation weight matrix according to the position information, obtain a set of excitation weights corresponding to the position information, and assign the set of excitation weights to the sound channels of the parametric array speaker so that some of the sound channels in the parametric array speaker are aligned with the position of the target object to emit sound in a direction; different position information corresponds to different excitation weights, and the sound field is moved by assigning different excitation weights to the parametric array speaker; The process of obtaining the incentive weight matrix includes: According to the radiation sound pressure p(x+(n-1)l) of each sound channel and the set excitation weights [α 1m ,α 2m ,…,α nm ], and the total sound field p radiated by the parametric array loudspeaker is obtained T (x), x is the moving position of the sound field; According to the maximum value p of the total sound field Tmax , get the position information x corresponding to the maximum value m , by the position information x m and incentive weight [α 1m ,α 2m ,…,α nm ] The incentive weight matrix is expressed as: Wherein, n is the number of sound channels, l is the distance between the sound channels, and m is the number of sound field movement positions, and both n and m are integers greater than or equal to 2.

2. The method for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 1, characterized in that: The total sound field p T (x) is expressed as: p T (x)=a 1m p(x)+a 2m p(x+l)+…+a nm p(x+(n-1)l).

3. The method for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 1, characterized in that: If the ultrasonic transducer array is divided into left and right channels, the left position information and right position information corresponding to the left and right channels are determined according to the position information of the target object, and a set of excitation weights are determined according to the left position information and the right position information.

4. The method for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 1, characterized in that: When the target object moves, the sound channels at different sound field moving positions are homogenized so that the sound pressure at different sound field moving positions is the same.

5. The method for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 4, characterized in that: The homogenization process includes adjusting the magnitude of the excitation voltage of the sound channel.

6. The method for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 1, characterized in that: The remaining sound emission channels except for some sound emission channels corresponding to the position information are controlled to emit low-frequency signals for low-frequency compensation of the sound field, where the low-frequency signals are signals below 1 KHz.

7. The method for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 1, characterized in that: The plurality of sound emission channels spaced apart along the first direction form a sound emission channel group, and the ultrasonic transducer array includes one or more sound emission channel groups arranged along one or more second directions.

8. The method for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 7, characterized in that: The distance between two adjacent sound channels and the distance between two adjacent sound channel groups are both 1 mm to 100 mm.

9. A system for achieving sound field movement based on a multi-channel parametric array speaker, characterized in that: include: An excitation weight matrix acquisition module is used to obtain the total sound field radiated by the parametric array speaker based on a set of excitation weights corresponding to the radiated sound pressure of each sound channel and each set sound field movement position, obtain the position information corresponding to the maximum value of the total sound field based on the maximum value, and obtain the excitation weight matrix from the position information and the excitation weights; A location recognition module is used to identify the location information of the target object; a sound field movement module, connected to the excitation weight matrix acquisition module, the position identification module, and the parametric array loudspeaker according to any one of claims 1 to 8, for calling the excitation weight matrix according to the position information to obtain a set of excitation weights corresponding to the position information, and assigning the set of excitation weights to the sound channels of the parametric array loudspeaker so that some of the sound channels in the parametric array loudspeaker are aligned with the position of the target object and emit sound in a directionally directed manner; Different position information corresponds to different excitation weights, and the sound field movement is achieved by assigning different excitation weights to the parametric array speakers.

10. The system for achieving sound field movement based on a multi-channel parametric array loudspeaker according to claim 9, characterized in that: The system further comprises: The sound field homogenization module is connected to the sound field movement module and the parametric array speaker, and is used to homogenize the sound channels at different positions during the movement of the target object so that the sound pressure at different positions is the same.

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