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CN109005496A - A kind of HRTF middle vertical plane orientation Enhancement Method - Google Patents

A kind of HRTF middle vertical plane orientation Enhancement Method Download PDF

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Publication number
CN109005496A
CN109005496A CN201810834254.1A CN201810834254A CN109005496A CN 109005496 A CN109005496 A CN 109005496A CN 201810834254 A CN201810834254 A CN 201810834254A CN 109005496 A CN109005496 A CN 109005496A
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azimuth
itd
hrtf
angle
enhanced
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曾向阳
路东东
黄婉秋
王蕾
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Northwestern Polytechnical University
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Northwestern Polytechnical University
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Publication of CN109005496A publication Critical patent/CN109005496A/en
Priority to CN201910201711.8A priority patent/CN109769195B/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H04S1/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H04S1/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
    • H04S1/005—For headphones

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Stereophonic System (AREA)

Abstract

The present invention provides a kind of HRTF middle vertical plane orientation Enhancement Methods, it is related to sound source field, the present invention is after knowing front or dead astern orientation and closest azimuthal ITD, ITD when head and front or dead astern deviation are 1 ° is obtained using interpolation method, original HRTF is transformed using the ITD, new HRTF is obtained, the HRTF that the present invention synthesizes does not have difference on frequency spectrum with original HRTF, but may make hearer to enhance orientation locating effect using the HRTF.The present invention compensates the ITD in confusing orientation on the basis of not changing original signal frequency spectrum, and the HRTF obtained using the compensation and dry audio signal carry out convolution, and the aspect sense of synthesis is good, can effectively promote human ear front and back position Auditory Perception.

Description

Method for enhancing vertical plane orientation in HRTF
Technical Field
The invention relates to the field of sound sources, in particular to an HRTF (head related transfer function) azimuth enhancement method.
Background
Early studies thought that the most important basis for auditory localization was the difference in sound signals between the two ears, which is also the basic idea of duplex theory. If the distances from the sound source to the ears are different, the direct sound waves emitted from the sound source generally have a sequential order when reaching the ears. For example, when the sound source is closer to the right side of the head, the direct sound wave is transmitted to the right ear first, and then to the left ear through diffraction of the head. This process creates a small time difference between the arrival of sound waves at both ears, called Interaural Time Difference (ITD), and the sound waves are attenuated when they are transmitted to the left ear due to the obstruction of the head, and the sound intensity heard at the ear close to the sound source by 1 is greater than that heard at the ear far away, creating an interaural intensity difference (I0 LD). The ITDs and ILDs are also commonly referred to as binaural features.
On the middle vertical plane, the time difference ITD when the sound source reaches two ears and the sound level difference of the two ears are the same, and at the moment, the method for positioning by applying the duplex theory is not feasible any more. The document "Improvement of front-back positioning of 3D sound-based generation in the 7th International Conference on Advanced Communication Technology,2005, ICACT2005" provides a method for enhancing the front and back positions to achieve positioning of the front and back, which uses a spectral difference method to achieve front and back positioning. However, this method changes the frequency spectrum of the original HRTF signal. By analyzing the correlation between the HRTF and the physiological parameters, the physiological parameters influencing the HRTF at 0 degrees and 0 degrees are different from the physiological parameters influencing the HRTF at 180 degrees and 0 degrees, and by analyzing the correlation between the orientation enhancement by using spectral subtraction and the physiological parameters, the related physiological parameters of the HRTF are changed compared with the HRTF without orientation enhancement. This is not in accordance with the actual situation. This method is possible in the sense of auditory perception, but it is not clearly explained in a physical sense.
Disclosure of Invention
To overcome the deficiencies of the prior art, the present invention primarily provides a new method for implementing azimuth enhancement.
The technical scheme adopted by the invention for solving the technical problem comprises the following steps:
the method comprises the following steps: respectively obtaining the azimuth angle (theta) needing to be enhanced by using a 10% rising edge method0Phi) and adjacent azimuth angle (theta) at the same pitch angle as the phi)1Phi) ITD; wherein (theta)0Phi) denotes pitch angle phi and azimuth angle theta0When enhanced orientation is desired, (θ)1Phi) represents the pitch angle phi and the azimuth angle theta0Azimuth θ in nearest neighbor test database1To obtain:
ITDlead(θ，φ)＝tL，η-tR，η(1)
wherein the ITDlead(θ, φ) represents a binaural time difference at the azimuth angle (θ, φ); t is tL,η，tR,ηrepresenting the starting time at which the HRIRs of the left and right ears first exceed the HRIR maximum amplitude percentage η, respectively;
step two: obtaining the ITD under the condition that the azimuth angle is 1 DEG deviation from the azimuth angle needing to be enhanced through an interpolation method:
wherein,to require enhanced orientation (theta)0Phi) ITD;is the azimuth (theta) most adjacent to the enhanced azimuth1Phi) ITD;representing azimuth angle theta0+1, the pitch angle is the binaural time difference at phi, theta0+1 represents the azimuth angle theta0An azimuth of 1 ° greater;
step three: angle of azimuth (theta)0Phi) is compensated, compensated (theta)0Phi) binaural time difference of
Step four: to (theta)0Phi), the HRTF at phi) is modified as follows:
if the nearest neighbor orientation (theta) is selected1Phi) is located at (theta)0On the left side of phi), then at the azimuth angle (theta)0Phi), zero padding is performed on the left side of the left ear HRIR; meanwhile, in order to ensure the length of the left ear and the right ear to be consistent, zero filling is carried out on the right side of the HRIR of the right ear, and the HRIR after modification is
Wherein,indicating a modified azimuth angle of (theta)0Phi) right ear head related transfer function;
indicating a modified azimuth angle of (theta)0Phi) left ear head related transfer function;to representAn all-zero array of rows and columns; r represents the right ear, L represents the left ear;
if the selected nearest azimuth is located at the right side of the azimuth to be enhanced, the zero padding mode is as follows:
will be modifiedSet to the tested direction as theta0And the head-related transfer function with the pitching angle phi is used for carrying out convolution on the head-related transfer function and the dry signal to obtain an audio signal with good azimuth sense, and the technology can realize the azimuth theta0And the pitch angle is the azimuth enhancement at phi.
The invention has the advantages that on the basis of not changing the original signal frequency spectrum, ITD of the confusable azimuth is compensated, the HRTF obtained by the compensation is convoluted with the dry audio signal, the synthesized signal azimuth sense is good, and the auditory sense of the front and back azimuths of human ears can be effectively improved.
Drawings
FIG. 1 is a flow chart of the present invention for vertical plane orientation enhancement.
FIG. 2 is a diagram of the frequency domain of the original signal in an embodiment of the present invention.
Fig. 3 is a frequency domain diagram after applying azimuth enhancement in an embodiment of the present invention.
Detailed Description
The present invention will be further explained with reference to the drawings and examples, taking the azimuth angle (0 ° ) as an example.
To overcome the deficiencies of the prior art, the present invention is directed to implementing azimuth enhancement by attempting to invent a new method. The invention can help to realize the direction enhancement at the front and back positions by slightly rotating the head. Because the position that the human ear can recognize is 3.6 degrees in the horizontal position, the human ear can hardly clearly distinguish (0 degrees ) from (0 degrees, 1 degrees); meanwhile, the HRTF at the (0 ° ) bearing reflects the auditory perception of the human ear on the front sound, but the auditory perception itself affects the sound, so that the sound is in the center of the head. The invention discloses a method for reconstructing an original HRTF by knowing the ITD of an azimuth right in front or behind and the nearest azimuth angle, applying an interpolation method to obtain the ITD when the deviation of the head from the azimuth right in front or behind is 1 degree, and applying the ITD to reconstruct the original HRTF to obtain a new HRTF. The synthesized HRTF has no difference with the original HRTF in frequency spectrum, but the application of the HRTF can enhance the azimuth positioning effect of a listener.
Although the orientation enhancement algorithm obtained by the spectral difference method can enhance the orientation feeling of a listener, the application of the method to obtain the front and back orientation spectrums actually changes the physiological factors influencing the frequency spectrums, which are two completely different HRTFs from the HRTF obtained by measurement. The invention provides a new orientation enhancement algorithm on the basis of not changing the HRTF frequency spectrum, so that a listener can accurately distinguish signal sources.
The technical scheme adopted by the invention for solving the technical problem comprises the following steps:
the method comprises the following steps: respectively obtaining the azimuth angle (theta) needing to be enhanced by using a 10% rising edge method0Phi) and adjacent azimuth angle (theta) at the same pitch angle as the phi)1Phi) ITD; wherein (theta)0Phi) denotes pitch angle phi and azimuth angle theta0When enhanced orientation is desired, (θ)1Phi) represents the pitch angle phi and the azimuth angle theta0Azimuth θ in nearest neighbor test database1To obtain:
ITDlead(θ，φ)＝tL，η-tR，η(1)
wherein the ITDlead(θ, φ) represents a binaural time difference at the azimuth angle (θ, φ); t is tL,η，tR,ηrespectively representing the starting time when the HRIR of the left ear and the right ear exceeds the maximum HRIR amplitude percentage eta for the first time, wherein eta is 10 percent.
Step two: obtaining the ITD under the condition that the azimuth angle is 1 DEG deviation from the azimuth angle needing to be enhanced through an interpolation method:
wherein,to require enhanced orientation (theta)0Phi) ITD;is the azimuth (theta) most adjacent to the enhanced azimuth1Phi) ITD;representing azimuth angle theta0+1, the pitch angle is the binaural time difference at phi, theta0+1 represents the azimuth angle theta0An azimuth of 1 ° greater;
step three: angle of azimuth (theta)0,φ) Compensating for the ITD of (theta)0Phi) binaural time difference of
Step four: to (theta)0Phi), the HRTF at phi) is modified as follows:
if the nearest neighbor orientation (theta) is selected1Phi) is located at (theta)0On the left side of phi), then at the azimuth angle (theta)0Phi), zero padding is performed on the left side of the left ear HRIR; meanwhile, in order to ensure the length of the left ear and the right ear to be consistent, zero filling is carried out on the right side of the HRIR of the right ear, and the HRIR after modification is
Wherein,indicating a modified azimuth angle of (theta)0Phi) right ear head related transfer function;
indicating a modified azimuth angle of (theta)0Phi) left ear head related transfer function;to representAn all-zero array of rows and columns; r represents the right ear, L represents the left ear;
if the selected nearest azimuth is located at the right side of the azimuth to be enhanced, the zero padding mode is as follows:
will be modifiedSet to the tested direction as theta0And the head-related transfer function with the pitching angle phi is used for carrying out convolution on the head-related transfer function and the dry signal to obtain an audio signal with good azimuth sense, and the technology can realize the azimuth theta0And the pitch angle is the azimuth enhancement at phi.
The examples are as follows:
the method comprises the following steps: referring to fig. 1, the ITDs at the azimuth (0 ° ) and the azimuth (5 °,0 °) adjacent to the same pitch angle are obtained by applying the 10% rising edge method:
ITDlead(θ,φ)＝tL,10％-tR,10％(5)
wherein the ITDlead(θ, φ) represents a binaural time difference at the azimuth angle (θ, φ); t is tL,10％、tR,10％Representing the starting time when the HRIRs of the left and right ears first exceeded 10% of their maximum amplitude, respectively.
Step two: the ITD at an azimuth offset of 1 ° from the azimuth to be enhanced, i.e., (1 °,0 °) is obtained by an interpolation method.
Wherein the ITD(0°,0°)For ITD at orientations (0 deg. ) requiring enhancement, ITD(5°,0°)To be most oriented with the enhancementThe ITD of the adjacent orientation, the closest orientation of the database used in the present invention is (5 °,0 °).
Step three: the ITD at azimuth angle (0 ° ) is compensated. After compensation (0 DEG ) the binaural time difference is
Step four: and (5) reconstructing the HRTF at the position of (0 degrees and 0 degrees).
If the closest azimuth (5 DEG, 0 DEG) is selected to be located on the right side of (0 DEG ), the azimuth angle (theta)0Phi) zero padding is performed on the left side of the right ear HRIR; and zero filling is carried out on the right side of the right ear HRIR for ensuring the length consistency of the left ear and the right ear.To rebuild the finished HRIR.
Wherein,representing the right ear head related transfer function at the position angle (0 DEG, phi DEG) after the transformation;
representing the related transfer function of the left ear head at the position of the transformed azimuth angle (0 degrees and 0 degrees);to representRow, 1 column of all-zero arrays; (0 ° ) is the azimuth angle that needs to be enhanced, R for the right ear and L for the left ear.
Compared with the HRTF obtained by measurement, the HRTF at the position of (0 degrees and 0 degrees) reconstructed by applying the method has better direction sense.
As can be seen from fig. 2 and fig. 3, after the method proposed by the present invention is applied to the azimuth enhancement, the frequency domain graph after the azimuth enhancement is not changed from the frequency domain graph of the original signal.

Claims (1)

1.一种HRTF中垂面方位增强方法，其特征在于包括下述步骤：1. a vertical plane orientation enhancement method in HRTF, is characterized in that comprising the steps: 步骤一：应用10％上升沿法分别获得需要增强的方位角(θ0,φ))以及与其同俯仰角下相邻方位角(θ1,φ)的ITD；其中，(θ0,φ)表示俯仰角为φ方位角为θ0时需要增强的方位，(θ1,φ)表示俯仰角为φ时与方位角θ0最相邻的测试数据库中的方位角θ1的方位，从而得到：Step 1: Apply the 10% rising edge method to obtain the ITD of the azimuth angle (θ 0 ,φ)) and the adjacent azimuth angle (θ 1 ,φ) at the same pitch angle to be enhanced respectively; where (θ 0 ,φ) Indicates the azimuth that needs to be enhanced when the pitch angle is φ and the azimuth angle is θ 0 , (θ 1 , φ) represents the azimuth θ 1 in the test database that is closest to the azimuth θ 0 when the pitch angle is φ, so that : ITDlead(θ，φ)＝tL，η-tR，η (1)ITD lead (θ, φ) = t L, η -t R, η (1) 其中，ITDlead(θ,φ)表示方位角(θ,φ)处的双耳时间差；tL,η，tR,η分别表示左、右耳的HRIR第一次超过HRIR最大幅值百分比η的起始时间；Among them, ITD lead (θ, φ) represents the binaural time difference at the azimuth (θ, φ); t L, η , t R, η respectively represent the HRIR of the left and right ears exceeding the HRIR maximum amplitude percentage η for the first time start time of 步骤二：通过插值方法获得在方位角为与需要增强的方位角1°偏差下的ITD：Step 2: Obtain the ITD at the azimuth with a deviation of 1° from the azimuth to be enhanced by interpolation method: 其中，为需要增强的方位(θ0,φ)的ITD；为与增强方位最邻近的方位(θ1,φ)的ITD；表示方位角为θ0+1，俯仰角为φ处的双耳时间差，θ0+1表示比方位角θ0大1°的方位；in, is the ITD of the orientation (θ 0 ,φ) that needs to be enhanced; is the ITD of the azimuth (θ 1 ,φ) closest to the enhanced azimuth; Indicates the binaural time difference where the azimuth angle is θ 0 +1 and the elevation angle is φ, and θ 0 +1 represents the azimuth that is 1° larger than the azimuth angle θ 0 ; 步骤三：对方位角(θ0,φ)处的ITD进行补偿，补偿后(θ0,φ)处双耳时间差为 Step 3: Compensate the ITD at the azimuth (θ 0 , φ), and the time difference between the two ears at (θ 0 , φ) after compensation is 步骤四：对(θ0,φ)处的HRTF进行如下改造：Step 4: Transform the HRTF at (θ 0 ,φ) as follows: 若选择的最邻近的方位(θ1,φ)位于(θ0,φ)的左侧，则在方位角(θ0,φ)处左耳HRIR在左侧进行补零；同时为保证左右耳长度一致，在右耳HRIR的右侧进行补零，改造后的HRIR为 If the selected closest azimuth (θ 1 , φ) is on the left side of (θ 0 , φ), then at the azimuth (θ 0 , φ), the HRIR of the left ear will be zero-filled on the left side; The length is the same, and the zero padding is performed on the right side of the HRIR of the right ear. The HRIR after transformation is 其中，表示改造后方位角为(θ0,φ)处右耳头相关传递函数；表示改造后方位角为(θ0,φ)处左耳头相关传递函数；表示行1列的全零阵列；R表示右耳，L表示左耳；in, Indicates the relative transfer function of the right ear at the azimuth angle (θ 0 , φ) after transformation; Indicates the relative transfer function of the left ear at the azimuth angle (θ 0 , φ) after transformation; express An all-zero array with one row and one column; R means the right ear, L means the left ear; 若选择的最邻近的方位位于待增强方位的右侧，则补零方式为：If the selected nearest azimuth is on the right side of the azimuth to be enhanced, the zero padding method is: 将改造后的设置为该被试在方位为θ0，俯仰角为φ的头相关传递函数，应用该头相关传递函数与干信号进行卷积可获得具有良好方位感的音频信号，该技术可以实现方位为θ0，俯仰角为φ处的方位增强。will be transformed Set the head-related transfer function of the subject at the azimuth of θ 0 and the pitch angle of φ, and apply the head-related transfer function to perform convolution with the dry signal to obtain an audio signal with a good sense of azimuth. This technology can realize the azimuth of θ 0 , the azimuth enhancement at elevation angle φ.
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