JP7422683B2 - microphone device - Google Patents

Description

The present invention relates to a microphone device that adjusts output.

The microphone device described in Patent Document 1 includes a plurality of microphones. The microphone device calculates a level ratio of signals from a plurality of microphones, and adjusts the output of the microphones based on the level ratio. This reduces the proximity effect that occurs when a sound source approaches the microphone.

Japanese Unexamined Patent Publication No. 4-181897

Generally, when a microphone device is powered on, ambient sounds are picked up by the microphone even when the speaker is not speaking, and sounds other than the intended sound are amplified. In order to prevent this from happening, a dedicated audio staff member may turn the microphone device on and off while checking how the speaker is using the microphone device. However, in this case, dedicated sound staff must be present at the venue etc. where the microphone devices are used, and each microphone device must be turned on and off each time it is used while checking how the speaker is using the microphone device. This requires a lot of effort.

SUMMARY OF THE INVENTION An object of the present invention is to provide a microphone device that can change the output of the microphone device according to how the user uses the microphone device without turning the power on or off.

(1) A microphone device according to one aspect of the present invention includes a first microphone, a second microphone arranged behind the first microphone in the directivity direction, and an intensity of a first output of the first microphone and a second microphone disposed behind the first microphone in the directivity direction. an output ratio calculation device that calculates an output ratio that is a ratio of the intensity of a second output of two microphones; an adjustment device that adjusts a first output of the first microphone to form a third output; an output control device that controls a third output of the adjustment device based on the adjustment device, and the output control device reduces the intensity of the third output output from the adjustment device when the output ratio is smaller than a threshold value. output as the fourth output.

The output ratio between the first microphone and the second microphone is a measure of the sound source distance between the sound source and the first microphone. When the sound source distance is large, the output ratio becomes small. According to the above configuration, the third output of the adjustment device is reduced when the output ratio is smaller than the threshold value. As a result, the output of the microphone device can be changed according to the user's use of the microphone device without the need for the audio staff or the like to turn the power on or off.

(2) In the above microphone device, the adjusting device is configured such that when the output ratio is a value equal to or higher than a reference value, the larger the output ratio is, the larger the decrease from the first output is, The third output is formed by adjusting the first output so that the intensity of the third output is a constant value, and the intensity of the third output after adjustment is equal to or higher than a predetermined value. However, when the output ratio is equal to or greater than the threshold value, the output control device outputs the third output as a fourth output without changing the intensity of the third output output from the adjustment device.

The smaller the sound source distance, the more the intensity of the first output becomes excessive, resulting in a harsher sound. In this regard, according to the above configuration, the smaller the sound source distance is, the larger the amount of decrease from the first output is made so that the intensity of the third output does not become smaller than a predetermined value, and the third output is increased relative to the sound source distance. The third output is formed such that . Thereby, the intensity of the third output can be made constant with respect to changes in the sound source distance.

(3) In the microphone device, when the output ratio is equal to or greater than a reference value, the adjustment device adjusts so that the larger the output ratio is, the larger the amount of decrease from the first output is. The third output is formed by adjusting the first output so that the intensity of the subsequent third output is large and the intensity of the adjusted third output is equal to or higher than a predetermined value, and the output control is performed. When the output ratio is equal to or greater than the threshold value, the device outputs the third output as the fourth output without changing the intensity of the third output output from the adjustment device.

The smaller the sound source distance, the more the intensity of the first output becomes excessive, resulting in a harsher sound. In this regard, according to the above configuration, the smaller the sound source distance is, the larger the amount of decrease from the first output is made so that the intensity of the third output does not become smaller than a predetermined value, and the smaller the sound source distance is, the larger the amount of decrease from the first output is. The third output is formed such that . This allows the third output to have an appropriate intensity depending on the sound source distance.

(4) In the above microphone device, the adjustment device adjusts the first output so that when the output ratio is equal to or higher than the reference value, the decrease width increases from high frequencies to low frequencies. forming a third output. According to this configuration, it is possible to suppress the proximity effect in which the sound in the low frequency region is emphasized as the sound source distance becomes smaller.

(5) In the microphone device, when the output ratio becomes smaller than the threshold, the output control device controls the magnitude of the third output over a predetermined hold time from the time when the output ratio becomes smaller than the threshold. is output as the fourth output without changing, and after the hold time has elapsed, the third output output from the adjustment device is attenuated at a rate of attenuation smaller than a predetermined rate.

According to the above configuration, instead of rapidly reducing the third output as soon as the output ratio becomes smaller than the threshold, the third output is output as the fourth output without changing the magnitude over the hold time, and then , the third output is attenuated at a damping speed lower than the predetermined speed. As a result, words can be smoothly connected, and the speaker's speech (speech, etc.) can be easily heard without interruptions between words.

(6) In the above microphone device, the second microphone is one of a plurality of second microphones arranged behind the first microphone in the directivity direction, and the output ratio calculation device is configured to For each pair of one microphone and each of the plurality of second microphones, an output ratio that is a ratio between the intensity of the first output of the first microphone and the intensity of the second output of the second microphone is calculated as a reference output ratio. , it is preferable to select one of the plurality of reference output ratios as the output ratio based on at least one of the plurality of reference output ratios.

The accuracy of estimating the sound source distance varies depending on the distance between the two microphones from which the output ratio is calculated. In the above configuration, a plurality of reference output ratios are calculated based on the intensity of the first output of the first microphone and the intensity of the second output of the plurality of second microphones. Then, one of the plurality of reference output ratios is selected as the output ratio based on at least one of the reference output ratios. This improves the accuracy of estimating the sound source distance.

According to the microphone device, the output of the microphone device can be changed depending on how the user uses the microphone device.

Schematic diagram of a microphone device. A block diagram of a microphone device. 3(a) shows the relationship between the output ratio and the sound source distance, FIG. 3(b) shows the relationship between the gain of the adjustment device and the sound source distance, and FIG. 3(c) shows the state of the output control device. A chart showing the relationship between and sound source distance. A chart showing frequency characteristics of the first output. The chart which shows the frequency characteristic of the 3rd output. A graph showing the intensity of the first output and the intensity of the third output with respect to the sound source distance. FIG. 7(a) is a chart showing changes in the output ratio over time, and FIG. 7(b) is a chart showing changes in the state of the output control device over time. FIG. 3 is a schematic diagram of a modification of the microphone device. Regarding the modified example of the microphone device, FIG. 9(a) is a chart showing the relationship between the first reference output ratio, the second reference output ratio, and the sound source distance, and FIG. 9(b) shows the adjustment in the first selection state. A chart showing the relationship between the gain of the device and the sound source distance, FIG. 9(c) is a chart showing the relationship between the gain of the adjusting device and the sound source distance in the second selection state, and FIG. A chart showing the relationship between the state of the output control device and the sound source distance in the selected state, and FIG. 9(e) is a chart showing the relationship between the state of the output control device and the sound source distance in the second selection state.

The microphone device will be described with reference to FIGS. 1 to 7.
As shown in FIG. 1, the microphone device 1 includes a main body 2 and a head 3 provided on the main body 2. The head unit 3 collects audio. The main body part 2 supports the head part 3. FIG. 1 shows a portable microphone device 1. As shown in FIG. The microphone device 1 may be of a stand type placed on a table or the floor.

As shown in FIG. 2, the microphone device 1 includes a first microphone 11, a second microphone 12, an output ratio calculation device 13, an adjustment device 14, and an output control device 15. The microphone device 1 may include a power supply device. The microphone device 1 may include power wiring.

The first microphone 11 has unidirectionality. The first microphone 11 is provided at the tip of the head section 3. The second microphone 12 has unidirectionality. The second microphone 12 may have the same structure as the first microphone 11, or may have a different structure from the first microphone 11. The second microphone 12 is provided in the head section 3 . The second microphone 12 is arranged behind the first microphone 11 in the directivity direction DA of the microphone device 1 . In this embodiment, the orientation direction DA coincides with the direction from the main body part 2 toward the head part 3. The pointing direction of the first microphone 11 and the pointing direction of the second microphone 12 both match the pointing direction DA of the microphone device 1. The rear DR indicates a direction opposite to the pointing direction DA.

The output ratio calculation device 13 calculates the output ratio SR. The output ratio SR indicates the ratio between the intensity of the first output S1 of the first microphone 11 and the intensity of the second output S2 of the second microphone 12. The ratio of the intensity of the first output S1 of the first microphone 11 to the intensity of the second output S2 of the second microphone 12 is the first output S1 of the first microphone 11 relative to the intensity B of the second output S2 of the second microphone 12. The ratio of the intensity A of (A/B) or the logarithm value (logA/B) of the ratio (A/B) is shown. The first output S1 and the second output S2 are acoustic signals. In one example, the output ratio SR is calculated as the logarithm of the ratio (A/B). The output ratio SR is calculated as the difference (logA-logB=logA/B) obtained by subtracting the logarithmic value of the intensity A of the first output S1 of the first microphone 11 from the logarithmic value of the intensity B of the second output S2 of the second microphone 12. May be calculated.

The sound source distance LS is defined as the distance between the first microphone 11 and the sound source on a line passing through the first microphone 11 and the second microphone 12. An example of a sound source is the user's mouth. In this embodiment, the sound source distance LS indicates the distance between the user's mouth and the first microphone 11. As the sound source distance LS increases, the sound intensity input to the first microphone 11 and the second microphone 12 decreases. Since the first microphone 11 is located closer to the user's mouth than the second microphone 12, the sound intensity input to the first microphone 11 is greater than the sound intensity input to the second microphone 12. The output ratio SR (logA/B), which is the ratio of the sound intensity input to the first microphone 11 and the sound intensity input to the second microphone 12, decreases as the sound source distance LS increases (see FIG. a)). In this way, the output ratio SR has a predetermined relationship with the sound source distance LS. The output ratio SR changes depending on the sound source distance LS, regardless of the volume of a person's voice. Therefore, the output ratio SR can be used as a guideline for the sound source distance LS.

FIG. 3A is a chart showing an example of the relationship between the sound source distance LS and the output ratio SR. According to the relationship between the sound source distance LS and the output ratio SR shown in FIG. 3A, when the output ratio SR is the first threshold value A1, the sound source distance LS is estimated to be the distance L1. When the output ratio SR is the reference value R1, the sound source distance LS is estimated to be the distance L2. FIG. 3(b) is an example of the gain used in the adjustment device 14 with respect to the sound source distance LS. FIG. 3C is an example of the state of the output control device 15 with respect to the sound source distance LS, which is used in the output control device 15. Note that the gain in FIG. 3(b) and the state of the output control device 15 in FIG. 3(c) are related to the sound source distance LS, but the gain and the state of the output control device 15 are related to the sound source distance LS. may be associated with the output ratio SR, which is the original data. In either case, the state of the gain and output control device 15 is associated with the magnitude of the output ratio SR. The state of the gain and output control device 15 is determined based on the magnitude of the output ratio SR.

The adjustment device 14 adjusts the first output S1 of the first microphone 11 to form a third output S3 based on the first output S1.
The adjustment device 14 is configured by a signal processing device. The signal processing device processes the first output S1 based on a program and outputs the processed signal as a third output S3. The program is stored in the signal processing device. The program adds various effects to the signal. Examples of effects include frequency response adjustment and intensity adjustment.

Adjustment device 14 performs a first adjustment. Preferably, the adjustment device 14 further performs a second adjustment. The first adjustment and the second adjustment may be performed separately, or may be performed simultaneously as one adjustment including the two adjustment contents.

In the first adjustment, the adjustment device 14 adjusts the output ratio SR so that when the output ratio SR is greater than or equal to the reference value R1, the larger the output ratio SR is, the larger the decrease LA from the first output S1 is. The first output S1 is adjusted so that the subsequent third output S3 has a constant value, and the intensity of the adjusted third output S3 is equal to or higher than the predetermined value CA. 3 output as S3 (see solid line in FIG. 6). The reference value R1 may be a value equal to the first threshold value A1 or a value different from the first threshold value A1. When the reference value R1 is a value different from the first threshold value A1, the reference value R1 is set to a value larger than the first threshold value A1. The amount of decrease LA indicates the amount of decrease in the intensity of the first output S1 input to the adjustment device 14. Specifically, the adjustment device 14 adjusts the magnitude of the first output S1 based on the gain shown in FIG. 3(b). The relationship between the output ratio SR and the gain is set in advance.

The first adjustment may be configured as follows. In the first adjustment, when the output ratio SR is greater than or equal to the reference value R1, the adjustment device 14 adjusts the larger the output ratio SR so that the larger the output ratio SR is, the larger the decrease LB from the first output S1 is. The first output S1 is adjusted so that the subsequent third output S3 has a large value and the intensity of the adjusted third output S3 is equal to or higher than the predetermined value CA, and the adjusted output is It is output as output S3 (see the dashed line in FIG. 6).

The smaller the sound source distance LS, the more the intensity of the first output S1 becomes excessive, resulting in a harsher sound. On the other hand, according to the first adjustment, the smaller the sound source distance LS, the larger the amount of decrease LA (LB) with respect to the first output S1 input to the adjustment device 14, so the intensity of the first output S1 becomes excessive. It is suppressed from becoming. Further, according to the first adjustment, when the sound source distance LS is less than or equal to the distance L2, the intensity of the adjusted third output S3 does not change with respect to a change in the sound source distance LS. In another example, according to the first adjustment, when the sound source distance LS is less than or equal to the distance L2, the smaller the sound source distance LS, the greater the intensity of the adjusted third output S3. As a result, the shorter the distance between the microphone device 1 and the mouth, the greater the output. Further, according to the first adjustment, the third output S3 after adjustment becomes equal to or higher than the predetermined value CA. For this reason, the value of the adjusted third output S3 does not become too small.

In the second adjustment, the adjustment device 14 adjusts the frequency characteristics of the first output S1 so that when the output ratio SR is equal to or greater than the reference value R1, the amount of decrease becomes larger from the high frequency to the low frequency. According to the second adjustment, the proximity effect is suppressed.

FIG. 4 shows the frequency characteristics of the first output S1 before the first adjustment and the second adjustment are performed. More specifically, FIG. 4 shows a plurality of waveforms of the first output S1 corresponding to sounds generated from a plurality of positions having different sound source distances LS. In this example, the sound source distances LS are 1 cm, 2 cm, 4 cm, 8 cm, 16 cm, and 32 cm. The smaller the sound source distance LS, the greater the intensity of the first output S1.

FIG. 5 shows the frequency characteristics of the third output S3 formed by performing the first adjustment and the second adjustment. Each of the intensities of the third output S3 corresponding to 1 cm, 2 cm, 4 cm, 8 cm, 16 cm, and 32 cm is smaller than the intensity of the original first output S1. Furthermore, the smaller the sound source distance LS, the greater the intensity of the third output S3. In FIG. 4, for comparison, the intensity of the first output S1 corresponding to the sound generated from a position where the sound source distance LS is 32 cm is set to "0", and the intensities of the other first outputs S1 are normalized. . Similarly, in FIG. 5, for comparison, the intensity of the third output S3 corresponding to the sound generated from the position where the sound source distance LS is 32 cm is set to "0", and the intensities of the other third outputs S3 are normalized. has been done.

As can be seen by comparing FIG. 4 and FIG. 5, according to the adjustment by the adjustment device 14, the intensity of the third output S3 is lower than the intensity of the first output S1 in the frequency range of 50 Hz to 20 kHz. Furthermore, the smaller the first output S1 is, the smaller the sound source distance LS is, the larger the intensity reduction LA (LB) is. This indicates that the first adjustment has been reflected. This suppresses overemphasis of the voice when the mouth approaches the microphone device 1. Furthermore, the smaller the first output S1 is at the sound source distance LS, the greater the intensity of the adjusted third output S3 (see FIG. 5). This indicates that the first adjustment has been reflected. According to the first adjustment, when the user brings the microphone device 1 close to the mouth during speech, the third output S3 increases. This allows the relationship between the distance between the user and the microphone device 1 and the volume to match the user's experience that the volume increases as the user approaches the microphone device.

As can be seen from a comparison between FIG. 4 and FIG. 5, according to the adjustment by the adjustment device 14, in the frequency range of 50 Hz to 20 kHz, the lower the frequency, the greater the decrease in the intensity of the first output S1. This indicates that the second adjustment for suppressing the proximity effect is reflected. This suppresses changes in sound quality (muffledness) when the mouth approaches the microphone device 1.

The output control device 15 controls the third output S3 of the adjustment device 14 based on the output ratio SR calculated by the output ratio calculation device 13. The output control device 15 has an open state in which the input third output S3 is output as is without changing the intensity of the third output S3, and a closed state in which the intensity of the third output S3 is reduced to a mute intensity. Take. For example, in the closed state, the output control device 15 reduces the intensity of the third output S3 by a predetermined reduction width LC. The output control device 15 switches between an open state and a closed state based on the value of the output ratio SR. The mute strength indicates the strength of a signal that cannot be heard by the speaker.

When the output ratio SR becomes larger than the second threshold value A2 in the closed state, the output control device 15 immediately enters the open state and directly operates the third output S3 of the adjustment device 14 without changing the intensity thereof. Output as 4 output S4. The second threshold A2 is larger than the first threshold A1.

When the output control device 15 is in the open state and the output ratio SR becomes smaller than the first threshold value A1, the output control device 15 enters the closed state and reduces the intensity of the third output S3 of the adjustment device 14 and outputs it as the fourth output S4. (hereinafter referred to as "output reduction operation"). Specifically, in the output reduction operation, the output control device 15 reduces the intensity of the third output S3 to the mute intensity by reducing the intensity of the third output S3 by a predetermined reduction width LC in the closed state. In this embodiment, "when the output ratio SR is smaller than the first threshold A1" indicates when the sound source distance LS is larger than the distance L1.

Preferably, when the output ratio SR becomes smaller than the first threshold value A1, the output control device 15 controls the magnitude of the third output S3 over a predetermined hold time TH from the point in time when the output ratio SR becomes smaller than the first threshold value A1. is outputted as the fourth output S4 without changing, and after the elapse of the hold time TH, the third output S3 is attenuated at a damping speed smaller than the predetermined speed.

An example of the third output S3 for the sound source distance LS will be described with reference to FIG. 6.
The graph in FIG. 6 shows the relationship between the intensity of the first output S1 output from the first microphone 11 and the intensity of the third output S3 formed by adjusting the first output S1. FIG. 6 shows a chart formed by plotting the intensity of the first output S1 and the intensity of the third output S3 against the sound source distance LS and the output ratio SR. As can be seen from FIG. 6, the first output S1 becomes smaller as the sound source distance LS becomes larger. When the sound source distance LS is greater than the distance L1, the intensity of the third output S3 is lowered by the output control device 15 by a predetermined reduction width LC from the intensity of the first output S1 (mute intensity). As can be seen from FIG. 6, when the sound source distance LS is less than or equal to the distance L2, the third output S3 is adjusted so that the lower the sound source distance LS becomes, the larger the decrease LA from the intensity of the first output S1 becomes. The value is greater than or equal to value CA. In one example, when the sound source distance LS is less than or equal to the distance L2 (when the output ratio SR is greater than or equal to the reference value R1), the third output S3 is constant with respect to the sound source distance LS (see the solid line in FIG. 6). In another example, when the sound source distance LS is less than or equal to the distance L2 (when the output ratio SR is greater than or equal to the reference value R1), the third output S3 increases as the sound source distance LS becomes smaller (see the dashed line in FIG. 6). .

FIG. 7 shows an example of the operation of the output control device 15. The chart shown in FIG. 7(a) shows changes in the output ratio SR with respect to time. The output ratio SR rises from its initial value at time t1, becomes constant at time t2, falls at time t3, and returns to its initial value at time t4. Such patterns emerge in speech. Specifically, this pattern occurs when a speaker creates a "pause" (a period of time during which no pronunciation is made) between words. The period from time t1 to time t4 is the time period during which words are uttered, and the period after time t4 is the time period corresponding to the "pause" between words. For such a pattern, the output control device 15 operates as shown in the chart shown in FIG. 7(b). The output control device 15 is in the closed state and becomes open at time t21 when the output ratio SR becomes larger than the second threshold value A2. That is, when the speaker starts speaking, the output control device 15 becomes open, and the third output S3 is output as the fourth output S4. Thereafter, in the open state, when the hold time TH has elapsed from the time t22 at which the output ratio SR becomes smaller than the first threshold A1, the output control device 15 controls the predetermined attenuation rate from the time t23. to the closed state. That is, after the speaker finishes speaking, the output control device 15 remains open for at least the hold time TH. As a result, when the speaker starts speaking after a short pause after finishing speaking, the output control device 15 outputs the sounds corresponding to these words as a continuous signal without interruption. Output. As a result, the sound reproduced by the speaker based on the output from the microphone device 1 becomes a natural and easy-to-listen sound without interruption.

The operation of this embodiment will be explained.
According to the microphone device 1 of this embodiment, when the output ratio SR is smaller than the first threshold value A1, the intensity of the third output S3 is reduced and output as the fourth output S4. Specifically, the output control device 15 lowers the intensity of the third output S3 to an intensity that cannot be heard through speaker reproduction ("mute intensity"), and outputs it as the fourth output S4.

For example, if the user's mouth moves far away from the microphone device 1 due to the user's actions, and the sound does not enter the microphone device 1, and the output ratio SR becomes smaller than the first threshold value A1, the output control device 15 is in the closed state, and the intensity of the third output S3 is reduced to the mute intensity. Further, even if audio such as BGM is played in a place far from the microphone device 1, if the output ratio SR is smaller than the first threshold value A1, the output control device 15 remains in the closed state. At this time, the output control device 15 lowers the intensity of the third output S3 to an intensity that cannot be heard through speaker reproduction ("mute intensity"), and outputs it as the fourth output S4. In this way, even if a sound far from the microphone device 1 is input to the microphone device 1, the strength of the signal of the sound is reduced, so that the distant sound is prevented from being amplified via the microphone device 1. be done.

As shown in FIG. 6, when the user's mouth approaches the microphone device 1 due to the user's actions and the output ratio SR becomes equal to or greater than the reference value R1, the adjusting device 14 adjusts the adjusted third position as the sound source distance LS approaches. The first output S1 is adjusted so that the intensity of the output S3 is reduced. Furthermore, as shown in FIG. 5, when the output ratio SR is equal to or higher than the reference value R1, the frequency characteristics of the adjusted third output S3 are adjusted so that the intensity is approximately constant from high frequency to low frequency. The frequency characteristics of S1 are adjusted. This suppresses the proximity effect.

As shown in FIG. 7, even when a "pause" is formed between words in speech, etc., the output ratio SR becomes a value smaller than the first threshold value A1. That is, situations in which the output ratio SR takes a value smaller than the first threshold value A1 occur in two cases: when the sound source distance LS becomes the distance L1, and when the intensity of the input sound is small. . When the output control device 15 enters the closed state at the moment when the output ratio SR becomes smaller than the first threshold value A1, the speaker's speech is interrupted. In this regard, as explained with reference to FIG. 7, the output control device 15 maintains the open state for at least the hold time TH from the time when the output ratio SR becomes smaller than the first threshold value A1, and the output control device 15 maintains the open state for at least the hold time TH, and is output as the fourth output S4 without changing. This allows the speaker's speech to be amplified into an uninterrupted, easy-to-hear voice.

The effects of this embodiment will be explained.
(1) In the microphone device 1, when the output ratio SR is smaller than the first threshold value A1 (threshold value), the output control device 15 reduces the intensity of the third output S3 of the adjustment device 14 and outputs it as the fourth output S4. do.

The output ratio SR between the first microphone 11 and the second microphone 12 is a measure of the sound source distance LS, which is the distance between the sound source and the first microphone 11. When the sound source distance LS is large, the output ratio SR becomes small. According to the above configuration, the intensity of the third output S3 of the adjustment device 14 is reduced when the output ratio SR is smaller than the first threshold value A1 (threshold value). As a result, the output of the microphone device 1 can be changed in accordance with the use of the microphone device 1 by the user without the need for the audio staff or the like to turn on/off the power of the microphone device 1.

(2) When the output ratio SR is greater than or equal to the reference value R1, the adjustment device 14 determines that the larger the output ratio SR is, the larger the decrease LA from the first output S1 is, The third output S3 is adjusted by adjusting the first output S1 so that the intensity of the third output S3 becomes a constant value, and so that the intensity of the third output S3 after adjustment becomes equal to or higher than the predetermined value CA. form. When the output ratio SR is equal to or greater than the first threshold value A1, the output control device 15 outputs the third output S3 outputted from the adjustment device 14 as the fourth output S4 without changing its intensity.

The smaller the sound source distance LS, the more the intensity of the first output S1 becomes excessive, resulting in a harsher sound. In this regard, according to the above configuration, the lower the sound source distance LS is, the larger the reduction amount LA from the first output S1 is, so that the intensity of the third output S3 does not become smaller than the predetermined value CA. The third output S3 is formed such that the third output S3 has a constant value. Thereby, the intensity of the third output S3 can be made constant with respect to changes in the sound source distance LS.

(3) The adjustment device 14 may adjust the third output S3 as follows. When the output ratio SR is greater than or equal to the reference value R1, the adjustment device 14 adjusts the amount of decrease LB from the first output S1 to a larger value as the output ratio SR becomes larger, and adjusts the adjusted third output as the output ratio SR becomes larger. The third output S3 is formed by adjusting the first output S1 so that the intensity of S3 increases and the intensity of the adjusted third output S3 becomes equal to or greater than a predetermined value CA. When the output ratio SR is equal to or greater than the first threshold value A1, the output control device 15 outputs the third output S3 outputted from the adjustment device 14 as the fourth output S4 without changing its intensity.

The smaller the sound source distance LS, the more the intensity of the first output S1 becomes excessive, resulting in a harsher sound. In this regard, according to the above configuration, the lower the sound source distance LS is, the larger the reduction amount LB from the first output S1 is, so that the intensity of the third output S3 does not become smaller than the predetermined value CA. The third output S3 is formed such that the smaller the third output S3 is, the larger the third output S3 becomes. This allows the third output S3 to have an appropriate intensity depending on the sound source distance LS.

(4) When the output ratio SR is equal to or greater than the reference value R1, the adjustment device 14 adjusts the first output S1 so as to increase the decrease in the third output S3 from the high frequency to the low frequency. Form. According to this configuration, it is possible to suppress the proximity effect in which the sound in the low frequency region is emphasized as the sound source distance LS becomes smaller.

(5) When the output ratio SR becomes smaller than the first threshold A1 (threshold), the output control device 15 controls the third output S3 for a predetermined hold time TH from the point in time when the output ratio SR becomes smaller than the first threshold A1. is outputted as the fourth output S4 without changing the magnitude thereof, and after the elapse of the hold time TH, the third output S3 outputted from the adjustment device 14 is attenuated at a damping speed smaller than the predetermined speed.

If the third output S3 is suddenly reduced as soon as the output ratio SR becomes smaller than the first threshold value A1, there is a possibility that the sound amplified via the microphone device 1 will be interrupted. For example, even during a short period when the speaker is not making a sound between words, the intensity of the third output S3 is lowered and output as the fourth output, so the background noise between the words is erased. As a result, the speaker's speech becomes unnatural and difficult to listen to, with gaps between words.

In this regard, in the above configuration, instead of rapidly decreasing the third output as soon as the output ratio SR becomes smaller than the first threshold value A1, the third output S3 is not changed in magnitude over the hold time TH, and the third output is increased. 4 output S4, and then attenuates the third output S3 at a lower attenuation speed than the predetermined speed. As a result, when the period between words is shorter than the hold time TH, the words will be connected smoothly, and the speaker's speech (speech, etc.) will not be interrupted between words. It becomes easier to listen to.

<Other embodiments>
The description regarding the embodiment is an illustration of the microphone device 1. The microphone device 1 can take the form of a combination of the following modifications and at least two mutually consistent modifications. In the following modified examples, parts common to the embodiment are given the same reference numerals as in the embodiment, and the explanation thereof will be omitted.

- With reference to FIG. 8, an example of a microphone device 1x including a plurality of second microphones will be described.
As the sound source distance LS increases, the output ratio SR decreases. When the output ratio SR becomes smaller, the change in the output ratio SR with respect to the change in the sound source distance LS becomes smaller, so the estimation error of the sound source distance LS estimated based on the output ratio SR becomes larger. On the other hand, as the distance between the first microphone 11 and the second microphone 12 increases, the output ratio SR also increases. However, if the distance between the first microphone 11 and the second microphone 12 is too large, the intensity of the second output S2 of the second microphone 12 will decrease, and the noise in the output ratio SR will increase. For this reason, multiple output ratios SR are calculated from multiple sets of microphones with different spacing distances, and an appropriate one is selected from among the multiple output ratios SR depending on the size of the sound source distance LS. It is preferable. A specific example will be explained below.

As shown in FIG. 8, the microphone device 1x includes a first microphone 11 and two second microphones 12 and 17. The two second microphones 12 and 17 are arranged behind the first microphone 11 in the directivity direction DA. The two second microphones 12 and 17 are arranged in a line along the directivity direction DA.

The output ratio calculation device 13 calculates the intensity of the first output S1 of the first microphone 11 and the second output S21 of the second microphones 12, 17 for each pair of the first microphone 11 and the two second microphones 12, 17. The ratio with the intensity of S22 is calculated as a first reference output ratio SRX1 and a second reference output ratio SRX2. The first reference output ratio SRX1 is calculated as the logarithm of the ratio (A/B1) of the intensity A of the first output S1 of the first microphone 11 to the intensity B1 of the second output S21 of the second microphone 12 on the front side. The second reference output ratio SRX2 is calculated as the logarithm of the ratio (A/B2) of the intensity A of the first output S1 of the first microphone 11 to the intensity B2 of the second output S22 of the second microphone 12 on the rear side. .

The output ratio calculation device 13 selects one of the two reference output ratios SRX as the "output ratio SR" depending on the magnitude of the sound source distance LS. The magnitude of the sound source distance LS is estimated based on at least one of the two reference output ratios SRX. In this modification, the "output ratio SR" has the same function as the "output ratio SR" in the microphone device 1 of the embodiment.

In one example, the output ratio calculation device 13 selects one of the first reference output ratio SRX1 and the second reference output ratio SRX2 as the output ratio SR based on the magnitude of the first reference output ratio SRX1. For example, the output ratio calculation device 13 selects the first reference output ratio SRX1 as the output ratio SR when the first reference output ratio SRX1 becomes a value equal to or greater than the determination value. The output ratio calculation device 13 selects the second reference output ratio SRX2 as the output ratio SR when the first reference output ratio SRX1 becomes a value less than the determination value. The determination value is a value that is set independently of the first threshold A1 shown in the embodiment.

The first reference output ratio SRX1 and the second reference output ratio SRX2 take different values. It is preferable that continuity be maintained when switching the reference output ratio SRX selected as the output ratio SR.

In this way, the output ratio SR takes the value of the first reference output ratio SRX1 or the second reference output ratio SRX2 depending on the sound source distance LS. Thereby, the output ratio SR becomes a reference value of the sound source distance LS with a small error compared to the actual sound source distance LS. By using such an output ratio SR in the adjustment device 14, the adjustment performed according to the sound source distance LS becomes more suitable for the sound source distance LS.

The operation of this modification will be explained below. The accuracy of estimating the sound source distance LS changes depending on the distance between the two microphones from which the output ratio SR is calculated. According to this modification, the output ratio calculation device 13 calculates two reference values based on the intensity of the first output S1 of the first microphone 11 and the intensity of the second outputs S21 and S22 of the two second microphones 12 and 17. Calculate the output ratio SRX. Then, one of the two reference output ratios SRX is selected as the output ratio SR based on at least one of the reference output ratios SRX. This improves the accuracy of estimating the sound source distance LS.

- Another example of the microphone device 1y including a plurality of second microphones 12 and 17 will be described with reference to FIGS. 8 and 9. Regarding the microphone device 1y, the arrangement relationship of the plurality of second microphones 12 and 17 is similar to the arrangement relationship in the microphone device 1x.

The microphone device 1y has a third threshold A3 and a fourth threshold A4 instead of the first threshold A1. Since the microphone device 1y has the two third threshold values A3 and the fourth threshold value A4, it is possible to change the sound source distance LS at which the output reduction operation is performed. The output lowering operation is a function of reducing the intensity of the third output S3 to the mute intensity. In one example, the third threshold value A3 and the fourth threshold value A4 are selected by, for example, a switching operation of a switch (not shown) attached to the microphone device 1y. Hereinafter, the selection of the third threshold A3 will be referred to as a "first selection state," and the selection of the fourth threshold A4 will be referred to as a "second selection state."

In this modification, the fourth threshold A4 is smaller than the third threshold A3. By switching from the third threshold A3 to the fourth threshold A4, the sound source distance LS at which the output control device 15 is in the closed state becomes farther from the mouth.

The output ratio calculation device 13 takes one of the first reference output ratio SRX1 and the second reference output ratio SRX2 as the output ratio SR, depending on the sound source distance LS. Specifically, the output ratio calculation device 13 selects the first reference output ratio SRX1 as the output ratio SR when the first reference output ratio SRX1 becomes a value equal to or greater than the determination value. The output ratio calculation device 13 selects the second reference output ratio SRX2 as the output ratio SR when the first reference output ratio SRX1 becomes a value less than the determination value. The adjustment device 14 and the output control device 15 use the value obtained by multiplying the second reference output ratio SRX2 by the correction coefficient as the output ratio SR at the time when the second reference output ratio SRX2 is selected as the output ratio SR. The correction coefficient is a correction coefficient for the second reference output ratio SRX2 in order to maintain continuity between the graph of the second reference output ratio SRX2 against the sound source distance LS and the graph of the first reference output ratio SRX1 against the sound source distance LS. be. The adjustment device 14 and the output control device 15 calculate the sound source distance LS based on the output ratio SR. The adjustment device 14 and the output control device 15 compare the output ratio SR with the third threshold A3 or the fourth threshold A4, and determine whether the output ratio SR is greater than or equal to the third threshold A3 or greater than the fourth threshold A4. Determine whether or not.

Referring to FIG. 9, an example of the gain of the adjustment device 14 and an example of the state of the output control device 15 when the third threshold value A3 is selected, and an example of the state of the adjustment device 14 when the fourth threshold value A4 is selected. An example of the gain and an example of the state of the output control device 15 will be explained.

In FIG. 9(a), a curve C1 indicates the first reference output ratio SRX1 with respect to the sound source distance LS. According to the relationship between the sound source distance LS and the first reference output ratio SRX1 shown by the curve C1, when the first reference output ratio SRX1 is the third threshold value A3, the sound source distance LS is estimated to be the distance L1.

In FIG. 9(a), a curve C2 indicates the second reference output ratio SRX2 with respect to the sound source distance LS. According to the relationship between the sound source distance LS and the second reference output ratio SRX2 shown by the curve C2, when the second reference output ratio SRX2 is the fourth threshold A4, the sound source distance LS is estimated to be the distance L3. Distance L3 is greater than distance L1.

FIG. 9(b) is an example of the gain for the sound source distance LS used by the adjustment device 14 in the first selection state. FIG. 9C shows an example of the gain for the sound source distance LS, which is used by the adjustment device 14 in the second selection state. FIG. 9(d) is an example of an open/closed state of the output control device 15 with respect to the sound source distance LS, which is used in the output control device 15 in the first selection state. FIG. 9E shows an example of the open/closed state of the output control device 15 with respect to the sound source distance LS, which is used in the output control device 15 in the second selection state.

The effects of this modification will be explained. The microphone device 1y of the modified example has a third threshold A3 and a fourth threshold A4 instead of the first threshold A1. The third threshold value A3 and the fourth threshold value A4 are switched by a switching operation of a switch. According to this configuration, the sound source distance LS for performing the output reduction operation can be changed.

DA...direction, DR...rear, LS...sound source distance, S1...first output, S2...second output, SR...output ratio, 1...microphone device, 2...main unit, 3...head, 11...first Microphones, 12, 17...Second microphone, 13...Output ratio calculation device, 14...Adjustment device, 15...Output control device.

Claims (7)

a first microphone;
a second microphone located behind the first microphone in the pointing direction;
an output ratio calculation device that calculates an output ratio that is a ratio of the intensity of the first output of the first microphone to the intensity of the second output of the second microphone;
an adjustment device that adjusts a first output of the first microphone to form a third output;
an output control device that controls the third output of the adjustment device based on the output ratio,
The adjustment device adjusts the output ratio so that when the output ratio is a reference value or more that is set as a threshold value or more, the larger the output ratio is, the larger the decrease from the first output is. The third output is adjusted by adjusting the first output so that the intensity of the subsequent third output becomes a constant value, and so that the intensity of the third output after adjustment becomes a predetermined value or more. form,
The output control device includes:
When the output ratio is a value equal to or greater than the threshold value, outputting the third output as a fourth output without changing the intensity of the third output output from the adjustment device;
When the output ratio is smaller than the threshold value, the microphone device reduces the intensity of the third output output from the adjustment device and outputs it as a fourth output. a first microphone;
a second microphone located behind the first microphone in the pointing direction;
an output ratio calculation device that calculates an output ratio that is a ratio of the intensity of the first output of the first microphone to the intensity of the second output of the second microphone;
an adjustment device that adjusts a first output of the first microphone to form a third output;
an output control device that controls the third output of the adjustment device based on the output ratio,
When the output ratio is a value equal to or greater than a reference value set as a value equal to or greater than a threshold value, the adjustment device is arranged such that the greater the output ratio is, the greater the decrease from the first output is, and the greater the output ratio is, the greater the adjustment device is. forming the third output by adjusting the first output so that the intensity of the subsequent third output is large and the intensity of the adjusted third output is equal to or higher than a predetermined value;
The output control device includes:
When the output ratio is a value equal to or greater than the threshold value, outputting the third output as a fourth output without changing the intensity of the third output output from the adjustment device;
When the output ratio is smaller than the threshold value, the microphone device reduces the intensity of the third output output from the adjustment device and outputs it as a fourth output. The adjustment device forms a third output by adjusting the first output so that when the output ratio is equal to or greater than the reference value, the amount of decrease increases from high frequencies to low frequencies. 3. The microphone device according to 1 or 2. When the output ratio becomes smaller than the threshold, the output control device controls the fourth output without changing the magnitude of the third output for a predetermined hold time from the time when the output ratio becomes smaller than the threshold. The microphone device according to any one of claims 1 to 3, wherein the third output is output as an output, and after the hold time has elapsed, the third output output from the adjustment device is attenuated at an attenuation speed smaller than a predetermined speed. The second microphone is one of a plurality of second microphones arranged behind the first microphone in the pointing direction,
The output ratio calculation device calculates the ratio of the intensity of the first output of the first microphone to the intensity of the second output of the second microphone for each pair of the first microphone and the plurality of second microphones. An output ratio is calculated as a reference output ratio, and one of the plurality of reference output ratios is selected as the output ratio based on at least one of the plurality of reference output ratios. The microphone device according to item 1. a first microphone;
a second microphone located behind the first microphone in the pointing direction;
an output ratio calculation device that calculates an output ratio that is a ratio of the intensity of the first output of the first microphone to the intensity of the second output of the second microphone;
an adjustment device that adjusts a first output of the first microphone to form a third output;
an output control device that controls the third output of the adjustment device based on the output ratio,
When the output ratio becomes smaller than the threshold, the output control device outputs the third output as a fourth output without changing the magnitude for a predetermined hold time from the time when the output ratio becomes smaller than the threshold. and after the hold time has elapsed, the third output output from the adjustment device is attenuated at an attenuation speed smaller than a predetermined speed and output as a fourth output. a first microphone;
a plurality of second microphones arranged in a line behind the first microphone in the pointing direction;
an output ratio calculation device that calculates an output ratio that is a ratio of the intensity of the first output of the first microphone to the intensity of the second output of the second microphone;
an adjustment device that adjusts a first output of the first microphone to form a third output;
an output control device that controls the third output of the adjustment device based on the output ratio,
The output ratio calculation device calculates the ratio of the intensity of the first output of the first microphone to the intensity of the second output of the second microphone for each pair of the first microphone and the plurality of second microphones. calculating the output ratio as a reference output ratio, and selecting one of the plurality of reference output ratios as the output ratio based on at least one of the plurality of reference output ratios;
The output control device lowers the intensity of the third output output from the adjustment device and outputs it as a fourth output when the output ratio is smaller than a threshold value. The microphone device.

Images