Clipping device and clipping method

Abstract

To make it desirable to easily discriminate voice in various noise environments.SOLUTION: A clipping device includes: a voice signal acquisition unit for acquiring a voice signal; an ambient sound input unit for inputting ambient sound; a frequency calculation unit for calculating a frequency whose intensity is the highest or a frequency of noise being a prescribed frequency band including the frequency with the highest intensity from ambient sound inputted to the ambient sound input unit; a clipping unit for determining a clipping amount which is an amount by which the voice signal is clipped according to the frequency of noise, which is calculated by the frequency calculation unit, and clipping-controlling amplitude of the voice signal based on the determined clipping amount; and an output unit for outputting the voice signal which is clipping-controlled.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a clipping device and a clipping method. [Background technology]

[0002] Patent Document 1 describes a hearing aid processing device for a portable wireless device that can improve the clarity of the voice of the other party in communication. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-218045 Summary of the Invention [Problem to be solved by the invention]

[0004] However, noise levels vary greatly depending on the environment, such as location and time. In contrast, the hearing aid processing device for portable wireless devices in Patent Document 1 only clips the input audio signal within a range of 25%±5% of the maximum amplitude. Therefore, it is desirable to make it easier to distinguish audio signals in a variety of noisy environments. [Means for solving the problem]

[0005] The clipping device of the present disclosure comprises: an audio signal acquisition unit that acquires an audio signal; an ambient sound input unit for inputting ambient sound; a frequency calculation unit that calculates the frequency of the noise having the highest intensity from the ambient sound input to the ambient sound input unit or a frequency in a predetermined frequency band including the highest intensity frequency; a clipping unit that determines a clipping amount, which is a magnitude of clipping of the audio signal, in accordance with the frequency of the noise calculated by the frequency calculation unit, and clips and controls the amplitude of the audio signal based on the determined clipping amount; an output unit that outputs the clipping-controlled audio signal; A clipping device comprising:

[0006] The clipping method of the present disclosure comprises: Acquire an audio signal, Input ambient sound, Calculating the frequency of noise that is the highest frequency or a predetermined frequency band including the highest frequency from the input ambient sound; determining a clipping amount, which is a magnitude at which the audio signal is clipped, in accordance with the calculated frequency of the noise, and clipping-controlling the amplitude of the audio signal based on the determined clipping amount; This is a clipping method in which the audio signal is subjected to clipping control and output. [Effects of the Invention]

[0007] The present disclosure makes it easier to distinguish sounds in a variety of noisy environments. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a configuration of a clipping device according to an embodiment; [Figure 2] 1 is a flowchart of a clipping method according to the first embodiment. [Figure 3] 10 is a flowchart of a clipping method according to a second embodiment. [Figure 4] This figure shows waveforms on an oscilloscope and a spectrum analyzer with no clipping, with the clipping amount set to 0%. [Figure 5] FIG. 10 shows waveforms of an oscilloscope and a spectrum analyzer clipped with a clipping amount of 10%. [Figure 6] FIG. 10 shows waveforms of an oscilloscope and a spectrum analyzer clipped with a clipping amount of 20%. [Figure 7]FIG. 10 shows waveforms of an oscilloscope and a spectrum analyzer clipped with a clipping amount of 50%. [Figure 8] FIG. 3 is an image diagram of noise frequencies in the clipping method according to the first embodiment. [Figure 9] 4 is a diagram illustrating an example of a frequency of noise and an amount of clipping according to the first embodiment. [Figure 10] FIG. 10 is an image diagram of noise frequencies and audio frequencies in the clipping method according to the second embodiment. [Figure 11] 10 is a diagram illustrating an example of a frequency difference between a frequency of an audio signal and a frequency of noise and an amount of clipping according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the invention according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential means for solving the problems. For clarity of explanation, the following description and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0010] (Description of Clipping Device According to an Embodiment) FIG. 1 is a block diagram showing the configuration of a clipping device according to an embodiment. FIG. 4 is a diagram showing waveforms of an oscilloscope and a spectrum analyzer without clipping, where the clipping amount is 0%. Specifically, the diagram shows waveforms of the oscilloscope and the spectrum analyzer when the amplitude of the audio signal is 100%, i.e., when the clipping threshold is ±0.0 and no clipping is performed. FIG. 5 is a diagram showing waveforms of the oscilloscope and the spectrum analyzer when clipping is performed with the clipping amount set to 10%. Specifically, the diagram shows waveforms of the oscilloscope and the spectrum analyzer when the amplitude of the audio signal is 90%, i.e., when the clipping threshold is ±0.9. FIG. 6 is a diagram showing waveforms of the oscilloscope and the spectrum analyzer when clipping is performed with the clipping amount set to 20%. Specifically, the diagram shows waveforms of the oscilloscope and the spectrum analyzer when the amplitude of the audio signal is 80%, i.e., when the clipping threshold is ±0.8. FIG. 7 is a diagram showing waveforms of the oscilloscope and the spectrum analyzer when clipping is performed with the clipping amount set to 50%. Specifically, the figures show waveforms of an oscilloscope and a spectrum analyzer when the amplitude of the audio signal is 50%, that is, when the clipping threshold is clipped at ±0.5. The clipping device according to the embodiment will be described with reference to FIGS. 1 and 4 to 7.

[0011] The clipping device of the present disclosure is an audio transmission device that makes it easier to distinguish audio when, for example, audio received from a remote location via a radio is played back in various noisy environments. Making audio easier to distinguish means making it easier to distinguish audio in a noisy environment.

[0012] As shown in Figure 4, if the audio signal is not clipped as shown on the left, a 1 kHz sound signal can be heard as shown on the right. However, such audio has low sound pressure and is easily hidden by noise. Sound pressure is the density of sound, and is the difference between loud and soft parts of the sound.

[0013] As shown in Figures 5, 6, and 7, clipping with clipping thresholds of ±0.9, ±0.8, and ±0.5, as shown in the left figure, results in distortion, as shown in the right figure. When an audio signal is distorted, harmonic components of the audio signal are generated and superimposed on the main audio signal, making the sound pressure higher than a signal without distortion. As the sound pressure increases, the difference between loud and soft parts becomes smaller, and the sound tends to be perceived as louder than an audio signal with a lower sound pressure, even at the same volume.

[0014] The volume of the harmonic components of the audio signal changes depending on the level of distortion in the audio signal, resulting in a change in sound pressure. Specifically, when the distortion of the audio signal is small, the volume of the harmonic components of the audio signal is small and the sound pressure is low. When the distortion of the audio signal is large, the volume of the harmonic components of the audio signal is large and the sound pressure is high. Increasing the sound pressure by distorting the audio signal makes it easier to distinguish voices in noisy environments. Furthermore, increasing the sound pressure in noisy environments, especially in low-frequency noise environments, tends to make it easier to distinguish voices.

[0015] That is, when the clipping threshold is reduced, distortion occurs more easily, and the sound pressure increases, making it easier to distinguish speech in a noisy environment.

[0016] As shown in FIG. 1, the clipping device 100 includes an audio signal acquisition unit 101, an ambient sound input unit 102, a frequency calculation unit 103, a clipping unit 104, and an output unit 105.

[0017] The audio signal acquisition unit 101 has a function of acquiring an audio signal. The audio signal is, for example, audio received by a radio. The ambient sound input unit 102 inputs ambient sound near the location where the audio signal is played. The ambient sound is sound around the device itself. The ambient sound input unit can be, for example, a microphone.

[0018] The frequency calculation unit 103 calculates the frequency of noise (also called the noise frequency), which is the frequency with the highest intensity or a predetermined frequency band including the frequency with the highest intensity, from the ambient sound input to the ambient sound input unit 102. For example, the frequency of the noise is the frequency at which the peak volume occurs, a predetermined frequency band including the frequency at which the peak volume occurs, the average frequency of the average volume, or a predetermined frequency band including the frequency at which the average volume occurs. The frequency calculation unit 103 may calculate the audio frequency of the audio signal acquired by the audio signal acquisition unit 101. The audio frequency is, for example, the frequency of the audio with the highest intensity (also called the audio frequency) among the audio received by a radio. The frequency difference is the difference between the frequency of the audio signal and the frequency of the noise. The frequency difference can be expressed as |frequency of audio signal - frequency of noise|.

[0019] The clipping unit 104 determines the clipping amount, which is the magnitude at which the audio signal is clipped, according to the frequency of the noise calculated by the frequency calculation unit, determines a clipping threshold based on the determined clipping amount, and controls clipping of the amplitude of the audio signal based on the determined clipping threshold. The clipping amount is the percentage of the amplitude to be clipped when the maximum amplitude is 100%. If the clipping amount is small, the percentage of clipping is small. Conversely, if the clipping amount is large, the percentage of clipping is large.

[0020] The clipping unit 104 may increase the clipping amount when the frequency of the noise is lower than a predetermined frequency, and decrease the clipping amount when the frequency of the noise is higher than the predetermined frequency. Furthermore, the clipping unit 104 may increase the clipping amount when the difference between the frequency of the noise and the frequency of the audio is smaller than the predetermined frequency difference, and decrease the clipping amount when the difference between the frequency of the noise and the frequency of the audio is larger than the predetermined frequency difference.

[0021] The clipping amount may have multiple predetermined values ​​depending on the frequency of the noise. Also, the clipping amount may have multiple predetermined values ​​depending on the difference between the frequency of the noise and the frequency of the voice. In this way, the clipping amount can be determined in multiple stages.

[0022] The noise frequency may be processed to remove the sound output by the device itself. This is to prevent the sound output by the device itself from affecting the noise frequency. Also, if the audio signal is a single tone, the clipping amount may be set to 0%. This is because if an audio signal is used as a control signal for a single tone, distortion will cause malfunction.

[0023] The clipping-controlled audio signal is output from the output unit 105. The output unit 105 may be a speaker, an earphone, a headphone, or the like.

[0024] The above configuration makes it easier to distinguish between sounds in a variety of noisy environments.

[0025] (Description of Clipping Method According to First Embodiment) Fig. 2 is a flowchart of the clipping method according to the first embodiment. Fig. 8 is an image diagram of noise frequencies in the clipping method according to the first embodiment. Fig. 9 is an example of noise frequencies and clipping amounts in the first embodiment. The clipping method according to the first embodiment will be described with reference to Figs. 2, 8 and 9.

[0026] As shown in FIG. 2, first, an audio signal is acquired (step S201). For example, the audio signal acquisition unit 101 acquires an audio signal from a remote location received by a wireless device. Next, ambient sound is input (step S202). Ambient sound near the device is input to the ambient sound input unit 102. Next, it is determined whether the frequency of the ambient noise is higher or lower than a predetermined frequency (step S203). The frequency calculation unit 103 calculates the frequency of the ambient sound and determines whether the frequency of the noise is higher or lower than the predetermined frequency. If the frequency of the noise is lower than the predetermined frequency (low in step S203), the clipping unit 104 increases the clipping amount (step S204). If the frequency of the noise is higher than the predetermined frequency (high in step S203), the clipping unit 104 decreases the clipping amount (step S205). After clipping control, the output unit 105 outputs audio (step S206). After the audio is output, the processing ends.

[0027] In the example shown in Figure 8, the noise frequency is 300 Hz. As shown in Figure 9, for example, the clipping amount is set to 0% when the noise frequency is 2001 Hz or higher, and the clipping amount increases as the noise frequency decreases, and when the noise frequency is between 0 and 300 Hz, the clipping amount is set to 25%. This is because voice tends to be more difficult to distinguish when the noise frequency is low than when it is high. This makes it easier to distinguish voices in a variety of noisy environments.

[0028] (Description of Clipping Method According to Second Embodiment) Fig. 3 is a flowchart of the clipping method according to the second embodiment. Fig. 10 is an image diagram of the noise frequency and the audio frequency in the clipping method according to the second embodiment. Fig. 11 is an example of the frequency difference between the audio signal frequency and the noise frequency and the clipping amount according to the second embodiment. The clipping method according to the second embodiment will be described with reference to Figs. 3, 10 and 11.

[0029] As shown in FIG. 3, first, an audio signal is acquired (step S301). For example, the audio signal acquisition unit 101 acquires an audio signal from a remote location received by a wireless device. Next, ambient sound is input (step S302). Ambient sound near the device is input to the ambient sound input unit 102. Next, it is determined whether the frequency difference between the audio frequency and the noise frequency is larger or smaller than a predetermined frequency difference (step S303). The frequency calculation unit 103 calculates the frequency of the audio frequency and the ambient sound, and determines whether the frequency difference between the audio frequency and the noise frequency is larger or smaller than the predetermined frequency difference. If the frequency difference is smaller than the predetermined frequency difference (small in step S303), the clipping unit 104 increases the clipping amount (step S304). If the frequency difference is larger than the predetermined frequency difference, the clipping unit 104 decreases the clipping amount (step S305). After clipping control is performed, the output unit 105 outputs audio (step S306). After the audio is output, the processing ends.

[0030] In the example shown in Figure 10, the noise frequency is 300 Hz and the voice frequency is 1000 Hz. As shown in Figure 11, for example, when the frequency difference is 2001 Hz or more, the clipping amount is set to 0%, and as the frequency difference becomes smaller, the clipping amount is increased, and when the frequency difference is between 0 and 200 Hz, the clipping amount is set to 25%. This is because when the frequency difference between the noise frequency and the voice frequency is large, the voice signal is less likely to be buried in the noise, making it easier to distinguish the voice, and when the frequency difference is small, the voice signal is more likely to be buried in the noise, making it difficult to distinguish the voice. This makes it easier to distinguish voices in a variety of noisy environments.

[0031] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention. [Explanation of symbols]

[0032] 100 Clipping device, 101 Audio signal acquisition unit, 102 Ambient sound input unit, 103 Frequency calculation unit, 104 Clipping unit, 105 Output unit

Claims

1. an audio signal acquisition unit that acquires an audio signal; an ambient sound input unit for inputting ambient sound; a frequency calculation unit that calculates the frequency of the ambient sound inputted to the ambient sound input unit, or the frequency of noise in a predetermined frequency band including the frequency of the ambient sound inputted to the ambient sound input unit; a clipping unit that determines a clipping amount, which is a magnitude of clipping of the audio signal, in accordance with the frequency of the noise calculated by the frequency calculation unit, and clips and controls the amplitude of the audio signal based on the determined clipping amount; an output unit that outputs the clipping-controlled audio signal; A clipping device comprising:

2. 2. The clipping device according to claim 1, wherein the clipping unit determines the clipping amount to be large when the frequency of the noise is lower than a predetermined frequency, and determines the clipping amount to be small when the frequency of the noise is higher than the predetermined frequency.

3. the frequency calculation unit calculates a frequency of the audio signal having the highest intensity among the frequencies of the audio signal acquired by the audio signal acquisition unit; 2. The clipping device according to claim 1, wherein the clipping unit determines the clipping amount to be large when a frequency difference between the noise frequency and the voice frequency is smaller than a predetermined frequency difference, and determines the clipping amount to be small when the frequency difference between the noise frequency and the voice frequency is larger than the predetermined frequency difference.

4. 4. The clipping device according to claim 1, wherein the frequency of the noise is an average frequency of an average volume or a predetermined frequency band including the average frequency of the average volume.

5. Acquire an audio signal, Input ambient sound, Calculating the frequency of the noise with the highest intensity from the input ambient sound or the frequency of the noise with the highest intensity in a predetermined frequency band; determining a clipping amount, which is a magnitude at which the audio signal is clipped, in accordance with the calculated frequency of the noise, and clipping-controlling the amplitude of the audio signal based on the determined clipping amount; A clipping method in which the audio signal is clipped and output.

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