WO1991011077A1

WO1991011077A1 - Sound reproducing device

Info

Publication number: WO1991011077A1
Application number: PCT/JP1991/000028
Authority: WO
Inventors: Atsushi Nagayoshi; Koichi Higuchi; Kazutoshi Yamaguchi; Eiichi Takakura; Masataka Saito; Fusanori I
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 1990-01-19
Filing date: 1991-01-16
Publication date: 1991-07-25
Also published as: DE69114772T2; EP0464222B1; DE69114772D1; EP0464222A1; EP0464222A4

Abstract

A sound reproducing device suitable for use with a headphone of the open-air type in noisy environment. The frequency band of sounds leaking out when the headphone is put on is measured in advance, and the leakage from the headphone is controlled by switching a filter for attenuating the leakage frequency band when the headphone is being put on. Moreover, noise frequency characteristics are measured in advance, a low frequency band is reinforced to correspond to the above characteristics, and operation of the filter is changed over to attenuate the high frequency band that includes the above sound leakage frequency band.

Description

Specification

Title of invention

Sound reproduction device

Technical field

The present invention relates to a headphone of an open-air type, such as a portable type tape player or a CD player. Accordingly, the present invention relates to a sound reproducing device for performing reproduction listening in noise.

Background art

In recent years, sound reproducing devices using open-air headphones have been developed to be “portable and convenient” due to the art door in the acoustic field. Many of them are seen in sound reproduction devices such as small stereo cassette tape players and portable CD players. I came.

The headphone of the above open-air type is a headphone with a so-called headpad that covers the pinna, or inside the pinna. There is a headphone for the inner type to be attached, and the above-mentioned sound reproducing device that uses these is used for cassette tape players and pockets. It is a compact CD player, a radio receiver with FM stereo, or a combination of these devices, all of which are small and convenient to carry. It is. Also, even when listening outdoors, since it is an open-air type as described above, you should be able to listen to the sounds of cars, horns, and signal sounds. It is possible to play and listen without any danger while walking outdoors.

However, in such a configuration, the open-air type However, since external sounds can be heard, the effects of the surrounding noise will be affected at the same time, and the reproduced sound from the headphone will leak to the surroundings. There was a problem.

In other words, when the noise frequency characteristics in a train or in a listening environment in a car are measured, as shown in Fig. 10, the flat frequency characteristics A of the sound reproducing device are obtained as shown in Fig. 10. They are the noise frequency characteristics B in the train and the noise frequency characteristics C in the vehicle. Although both frequency characteristics B and C have some deviations in the frequency band, both have a high noise level in the low frequency band and a low noise level in the high frequency band. It is a thing. Therefore, when trying to listen to the output of a playback device having the frequency characteristic A, the low-frequency band is buried in the noise in both the train and the car. Unfortunately, the sound in the high frequency band is emphasized, and if you try to listen to the low frequencies well and raise the volume, the high frequencies will be emphasized further. There was a problem. This applies, for example, to listening alone by a headphone on a train and also listening alone by a headphone on a train. O

Also, in a train, if the headphone is an open-air type, sound leakage to the surrounding area becomes a problem. Fig. 11 and Fig. 12 show the results of the measurement of the sound leakage. Fig. 11 shows the sound leakage frequency characteristics D measured under the conditions shown in Fig. 12 for the headphone of the conventional open-air type. FIG. That is, the headphone H is attached to the ear La of the listener L and is placed at a position separated from the ear La by a distance of about 30 cm. The sound leak is measured by sound level meter M. here , The surrounding environment is a soundproof room, and the sound level meter M uses an A curve filter. As a result, as shown in Fig. 11, sound leakage increases when the frequency is equal to or higher than I kHz, the sound leakage frequency band characteristic D a, and the frequency decreases below lk Hz. In the band, the flat frequency characteristics Db of the noise level in the soundproof room are obtained. Thus, it can be seen that large sound leakage occurs in the high frequency band, and this was heard using the above open-air type. This can be a problem as a cause of sound leakage in some cases.

As described above, conventionally, when listening to the reproduced sound in a train or a car, the bass sound is very hard to hear due to the noise at the place, and the volleyball is used. There was a problem that the treble was abnormally emphasized by raising the sound, and the listener's own was also hard to hear. However, when there are many people around, as in a train, the volume of the volume tends to be large due to the noise of the surrounding train. For this reason, there was a problem that the sound leaked from the headphone was heard as loud noises to the surrounding people, and was annoying.

Disclosure of invention

In view of the above problems, the present invention is not affected by the noise characteristics of a train or a car as described above, and minimizes sound leakage. The purpose of this is to provide a sound reproducing device that enables comfortable reproduction for the people around it.

In order to solve the above problems, the sound reproducing device of the present invention has the following features: (1) In a noise environment used in a train or a car, for example, the noise is analyzed by frequency analysis of the noise amount. The frequency characteristics were measured in advance and the noise A filter that attenuates the high frequency band and enhances the low frequency band so as to correspond to the frequency characteristics is installed, and a control switch that switches the filter operation is provided. It is provided with a switch.

(2) In the configuration of (1) above, the high frequency band is attenuated and the low frequency band is enhanced so as to correspond to the train noise frequency characteristic and the car noise frequency characteristic, respectively. In addition to the provision of the first and second filters, the operation of the first or second filter and the non-operation of both filters are switched. A control switch is installed, and by switching the control switch, control is performed to obtain the frequency characteristics of the reproduced signal corresponding to the noise frequency characteristics of the train or car. It is configured as such.

(3) In addition, the sound leakage frequency band to the outside with the headphone attached is measured in advance, and an attenuation filter for attenuating the sound leakage frequency band is provided. A control switch for switching the operation of the attenuation filter is provided.

(4) In the configuration of (3) above, the frequency of the maximum attenuation level of the attenuation filter is changed to the maximum level of the frequency of the sound leakage frequency band measured in advance. It is a match.

(5) In the configuration of (3) above, the attenuation filter has a maximum attenuation level frequency of 4 to 8 k¾ and is the center frequency of the vocals. This is a damping filter with steep damping characteristics with almost no damping at 1 kHz.

(6) In addition, the noise frequency characteristics obtained by frequency analysis of the amount of noise in the noise environment used, and the sound leakage frequency band to the outside when the headphone is attached are shown. Measured in advance and the above noise frequency Switching of the operation of both filters, an enhancement filter that enhances the low frequency band to correspond to the characteristics, an attenuation filter that attenuates the sound leakage frequency band, and an attenuation filter that attenuates the sound leakage frequency band With a control switch.

According to the present invention, with the above-described configuration, the filter operation is performed by switching the control switch, and the frequency characteristic of the reproduction output is enhanced while the bass part is enhanced. When the headphone is used, the treble is attenuated and its frequency characteristics are controlled to correspond to the noise frequency characteristics. Sound leakage is attenuated as much as possible.

Also, when the switching switch is turned on and off, the sound leakage of the headphone in the frequency band is attenuated to the outside.

By switching the control switch, the frequency characteristics of the reproduced signal can be made to correspond to the above noise characteristics, and the headphone can be mounted in the headphone mounted state. The sound leakage from the phone to the outside can also be attenuated.

Brief description of the drawings

FIG. 1 is a block diagram showing a first embodiment of the present invention.

Fig. 2 is a circuit diagram of the main part

Fig. 3 shows the same frequency characteristics.

Fig. 4 is a block diagram showing the second embodiment.

FIG. 5 is a schematic circuit block diagram of a sound reproducing apparatus according to a third embodiment of the present invention.

Fig. 6 is a circuit diagram showing one block in Fig. 5 in detail. Fig. 7 shows the frequency characteristics of the third embodiment.

Fig. 8 is a sound leakage frequency characteristic diagram showing the first effect of the third embodiment.

Fig. 9 shows the frequency characteristics of yet another embodiment.

Fig. 10 shows noise frequency characteristics in trains and cars.

Fig. 11 shows the frequency characteristics of sound leakage from an open-air headphone of a conventional sound reproducing device.

FIG. 12 is a schematic diagram showing a measurement state when obtaining the characteristics of FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a sound reproducing apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic circuit block diagram of a sound reproducing apparatus according to an embodiment of the present invention. In the embodiment, a portable CD player is used as a stereo recorder. One channel of the type is shown. In FIG. 1, 1 includes a CD (connect disk) disc, and 2 includes an optical pickup for reading out signals from CD record 1. Traverse mechanism, 3 is a servo drive circuit for accurately controlling trapper mechanism 2, and 4 is a readout for trapper mechanism 2 5 is a signal processing circuit that processes the output signal, 5 is a DA connector that converts the digital signal that has been processed by the signal processing circuit 4 into an analog signal, In the evening, 6 is a knob for the DA converter 5 and 7 is a volume control volume for controlling the output of the buffer 6. is there . Reference numeral 8 denotes a headphone drive amplifier, which is used not only for driving the headphone but also for a filter 9 described later. Operation. Reference numeral 9 denotes a filter which is inserted into the feedback circuit of the headphone drive amplifier 8, and is inserted into the feedback circuit by a control switch 10 described later. The input / output frequency characteristics of the phone drive amplifier 8 change. 10 is an on / off control switch for filter operation, 11 is a headphone connection terminal to which the output of the headphone drive amplifier 8 is connected, and 1 2 Is one of the headphone channels connected to the headphone connection terminal 11. Reference numeral 13 denotes another channel, which is composed of the same circuit from the flip-flop 6 to the headphone 12. FIG. 2 is a circuit diagram showing details of the filter 9 including the headphone drive amplifier 8 to the control switch 10 from the headphone drive amplifier 8. In FIG. 2, reference numerals 8 and 10 denote the above-mentioned headphone drive amplifier and control switch, respectively. Reference numeral 10a denotes a filter-off-side terminal of the control switch 10; 10b denotes a filter-on-side terminal of the control switch 10; Reference numerals 14 and 15 denote resistors serving as gain setting elements for determining the input / output gain ij of the headphone drive amplifier 8. In addition, the resistors 16 and 18 and the capacitor 17 are used when the control switch 10 is set to the filter 'off side 10a' and the head switch is used. Low-frequency booster that operates as the-part of the gain setting element of the drive amplifier 8 and increases the low frequency band when the filter's on-side terminal 10b is set. It is a filter element and is a part of the above-mentioned filter 9. The capacitors 19 and 22 and the resistors 20 and 21 are switched when the switching switch 10 is set to the filter-side terminal 1Ob. In addition, only a high-frequency attenuation filter element for attenuating a high-frequency band, which is also a part of the filter 9. 23 is the input terminal of this circuit, and 24 is the same output terminal. FIG. 3 is a frequency characteristic diagram showing the relationship between the input / output frequency characteristics of the circuit shown in FIG. 2 and the train noise frequency characteristics and the vehicle noise frequency characteristics shown in FIG. In the figure, 25 is the train noise frequency characteristic, 26 is the vehicle noise frequency characteristic, 27 is the frequency characteristic of the reproduction output when the filter 9 is turned off, and 28 is the same. This is the frequency characteristic of the playback output when the operation of router 9 is on.

The operation of the sound reproducing device configured as described above will be described below with reference to FIGS. 1, 2, and 3. FIG.

In Fig. 3, as can be seen from the train noise frequency characteristic 25, the vehicle noise frequency characteristic 26, and the frequency characteristic 27 when the filter 9 is turned off. In both trains and cars, the noise in the low frequency band is high, but the noise in the high frequency band is low. Therefore, the low frequency band in the output from the headphone 12 for the listener is canceled out by noise and is hard to hear, and conversely, the high frequency band is Easy to listen to because the SZN ratio with noise is large. Therefore, if the control switch 10 is set to the filter-on terminal 10b, the reproduced output will be a filter in which the low frequency band is enhanced and the high frequency band is attenuated. The frequency characteristic of the operation of the data horn 9 is 28, and the low frequency band in the output from the headphone 12 is enhanced for the listener, so the noise is reduced due to the enhancement. It is easy to hear without being erased, and conversely, the high-frequency band that was heard until it is too weak is attenuated because it is attenuated. Become . However, since it attenuates the portion of the high-frequency band Da that leaks from the headphone shown in Fig. 6, it is difficult for surrounding people on the train or in the car. Thus, it is also possible to prevent inconvenience caused by sound leakage. As described above, according to the present embodiment, the train noise frequency characteristic 25 and the car noise frequency characteristic 26 are measured in advance, and the two noise frequency characteristics are measured. By providing a filter 9 that attenuates the high frequency band and enhances the low frequency band, and a control switch 10 that switches its operation, 3 By turning the control switch 10 on and off as shown in the figure, it is necessary to listen to the playback sound in the noise. Provides a good sound, and reduces sound leakage to surrounding areas when using an open-air type headphone. Is possible.

Next, a sound reproducing apparatus according to a second embodiment of the present invention will be described.

FIG. 4 is a schematic circuit block diagram of a sound reproducing apparatus according to a second embodiment of the present invention, which is a partial modification of the first embodiment. . In the figure, reference numeral 29 denotes a volume control volume for controlling the output amount from the preceding stage. Reference numeral 30 denotes a headphone drive amplifier, which not only drives the headphone but also operates as a file evening operation described later. Go. Reference numeral 31 denotes a first filter which is inserted into the feedback circuit of the headphone drive amplifier 30 and measures the noise frequency characteristics of the train in advance and determines the noise frequency. The high frequency band is attenuated to correspond to the characteristics, and the low frequency band is augmented. Therefore, the feedback circuit is provided to the control switch 33 described later. When input to the headphone, the input / output frequency characteristics of the headphone drive amplifier 30 change. Reference numeral 32 denotes a second filter which is inserted into the feedback circuit of the headphone drive amplifier 30 and has a characteristic different from that of the first filter 31 described above. The vehicle noise frequency characteristics are measured in advance and the noise frequency is measured. The high frequency band is attenuated to correspond to the wave number characteristics, and the low frequency band is augmented.The control switch 33 described later inputs the feedback circuit. When this is done, the input / output frequency characteristics of the headphone drive amplifier 30 change with characteristics different from those of the first filter. 3 3 is a filter operation on / off control switch, 34 is a headphone connection terminal to which the output of the headphone drive amplifier 30 is connected, 3 Reference numeral 5 denotes one channel of the headphone connected to the headphone connection terminal 34. The operation of the sound reproducing apparatus configured as described above will be described below with reference to FIGS. 4 and 3. In Fig. 3 above, as can be seen from the train noise frequency characteristics 25 and the vehicle noise frequency characteristics 26, there is a clear difference between the two noise frequency characteristics. The most suitable first filter 31 and second filter 32 corresponding to the noise frequency characteristics are installed, and the control switch 3 can be selected by the listener. By switching 3, the sound is more balanced and more suitable for the environment around the listener. However, since the high frequency band leaking from the headphone is attenuated in accordance with the surrounding environment, sound leaks to surrounding people in the train or in the car. Can also prevent inconvenience caused by the

As described above, according to the second embodiment, the train noise frequency characteristics 25 and the vehicle noise frequency characteristics 26 are measured in advance, and the above-described noise frequency characteristics are respectively corresponded. A first filter 31 and a second filter 32 that attenuate the high frequency band and enhance the low frequency band, and a control switch that switches the operation of the first filter 31 and the second filter 32. By setting the switch 33, the switching of the control switch 33 can reduce noise in the noise. If you need to listen to the playback of a sound, it can provide a good sound with a good balance, as well as an open-air type headphone. This makes it possible to reduce sound leakage to the surroundings when using a button.

In the embodiment described above, the filter characteristics are limited to the train noise frequency characteristics and the vehicle noise frequency characteristics. In an environment where noise of vehicles and other characteristics is generated other than a car, the noise frequency characteristics of the surrounding environment are measured in advance, and a file corresponding to the noise frequency characteristics is measured. The same effect can be obtained by setting the data characteristics.

Also, in the above-described embodiment, the case where the playback signal is listened to by the age of the open-ended type has been described. May be the case. For example, if you listen in the car, you can play it back through the speakers of the car stereo, but in this case, the person playing the car and the car The noise and noise will be mixed and heard. Therefore, if reproduced by the above-described device of the present invention, even in the case of listening in the noise of a vehicle, the reproduced sound can be reproduced in a well-balanced manner even if the speaker is reproduced. You can do this.

Next, a sound reproducing device according to a third embodiment of the present invention will be described. This embodiment focuses on the attenuation of the sound leakage frequency band D a shown in FIG. 11 described above, and does not apply to the high frequency region where no sound leakage occurs. In particular, the fact that it does not attenuate makes it possible to minimize the audible artifacts in the high frequency range.

FIG. 5 is a schematic circuit block diagram of a sound reproducing apparatus according to a third embodiment of the present invention. In the embodiment, a tape player stereo is shown. The type is indicated. In Fig. 5, 41 is magnetic A magnetic head for extracting an audio electric signal from a tape (not shown), 42 is a preamplifier having a built-in equalizer circuit, and 43 is a noise reducer. The left and right channels are used to input the output signal of the noise reduction circuit 43 and attenuate and output only a specific frequency band. A damping filter provided independently of the filter, 45 is a volume control unit that receives the output of the damping filter, and 46 is a circuit that boosts the bass range. A power amplifier with bass enhancement circuit that can drive a low impedance load, 47 is the head of the inner type, and the horn and 48 are the attenuation A control switch that can switch the router between operating and non-operating (a state in which the input and output do not have frequency characteristics).

FIG. 6 is a circuit diagram showing the details of the channel and the control switch 48 on only one side of the attenuation filter 44. In Fig. 6, 49 and 50 are the input and output terminals of the attenuation fin- olator 44, respectively. 51 is a semiconductor inductor composed of one transistor stone, and 52 is a resonance capacitor connected in series with the semiconductor inductor 51 so as to perform series resonance. It is a capacitor. Reference numeral 53 denotes a switching circuit for supplying the output of the control switch 48 to the semiconductor inductor 51.

The operation of the sound reproducing apparatus configured as described above will be described below with reference to FIGS. 5, 6, and 7. FIG.

The attenuation filter 44 corresponds to the previously measured level (6 kHz) of the maximum level of the sound leakage frequency characteristic shown in FIG. 11 and is set to this frequency (6 kHz). ) Is the notch filter with the maximum attenuation value. Therefore, the series resonance circuit composed of the semiconductor inductor 51 and the resonance capacitor 52 has a resonance frequency of 6 kHz. The constants have been determined so as to be as follows. As can be seen from FIG. 6, when the control switch 48 is set to 0 N, the semiconductor circuit 51 is energized and operated, so that the resonance circuit operates and the attenuation filter is operated. The filter 44 works as a notch filter having a center frequency of 6 kHz. Conversely, when the control switch 48 is set to 0FF, the semiconductor inductor 51 does not conduct electricity, so the attenuation filter 44 is set to a notch filter. As a result, there is no frequency characteristic between the input and output 49 and 50. From the above, the frequency characteristics of the entire circuit block of FIG. 5 are as shown in FIG. In FIG. 7, 54a shows the frequency characteristics when the control switch 480FF is used, and 54b shows the frequency characteristics when the control switch 480N is used. ing . As can be seen in FIG. 7, the characteristics of the attenuation filter 44 have almost no effect on the center frequency of the vocals, 1 kHz. For the purpose and to maximize the damping effect at 6 kHz, the Q of the resonant circuit was increased as much as possible. As a result, an attenuation level of 12 dB was realized at 6 kHz.

As described above, according to the third embodiment, the attenuation filter 44 for attenuating the sound leakage frequency band and the control switch 48 for switching the operation thereof are provided. By installing the control switch 48 as shown in Fig. 8, the control switch 48 can be set to 0 N · 0 FF to reduce sound leakage when necessary. And are possible. In FIG. 8, 55a shows the frequency characteristics when the control switch 48 is OFF, and 55b shows the frequency characteristics when the control switch 48 is ON.

FIG. 9 shows a frequency characteristic diagram based on still another embodiment. This example is based on the attenuation filter of the sound leakage frequency band of the third embodiment described above and the low frequency band of the first or second embodiment. It is a combination of only enhancement filters. That is, in Fig. 9, reference numeral 56 denotes the noise frequency characteristic obtained by frequency-analyzing the noise in the train.In contrast, the reproduction frequency characteristic 54c corresponds to the lower frequency. The band is enhanced, and the sound leakage frequency band centered at 6 k 減衰 is attenuated with a steep attenuation characteristic.

In this example, as can be seen from FIG. 9, in the train, the noise in the low-pitched portion is large but the noise in the high-pitched portion is small. Therefore, for the listener, the low-pitched portion in the output from the headphone 47 is buried in the noise and cannot be heard, and conversely, the high-pitched portion has a large SN ratio with the noise. Easy to hear. Therefore, when operating the attenuation circuit of the sound leakage frequency band and the operation of the boost circuit for the low frequency band, it is easy for the listeners in the train to hear the low-pitched sound that cannot be heard, and at the same time, the noise is increased. It is possible to attenuate the treble that has been heard so far to an appropriate level, thereby providing more audible and more natural sound quality. I can do it. However, it is possible to prevent the surrounding passengers on the train from being disturbed by sound leakage.

Note that the semiconductor inductor 16 in the embodiment may be a so-called inductor (coinole) that is a passive element.

Headphones 12 and 47 also include those of the recently used auricular insertion types.

Industrial applicability

As described above, the present invention measures in advance the noise frequency characteristics obtained by frequency-analyzing the noise in a train, the noise frequency characteristics obtained by frequency-analyzing the noise in a car, and the like. A filter that attenuates the high frequency band and enhances the low frequency band At the same time, a control switch for switching this filter operation is installed, and by switching the control switch, the frequency characteristic of the reproduced signal is adjusted to the above-mentioned value. The listener is able to obtain a sound that is well-balanced and suitable for the surrounding environment because of the noise frequency characteristics.

Also, the present invention provides an attenuation filter for attenuating a sound leakage frequency band and a control switch for switching an operation of the attenuation filter, and the control switch for the control switch is provided. By turning the switch on and off, it is possible to actively control sound leakage from the headphone to the outside in the mounted state, When used in a place with a lot of noise, such as inside an object, or in crowds, it is possible to reduce external sound leakage if necessary. To provide a sense of security to the listener, to avoid inconvenience to the surrounding people, and to provide a more natural sound quality than under noise. This is a very effective invention that can be obtained.

Claims

The scope of the claims

In a noise environment used in trains and cars, the noise frequency is analyzed in advance to measure the noise frequency characteristics, and the high frequency band is adjusted to correspond to the above noise frequency characteristics. In addition to providing a filter that attenuates and enhances the low frequency band, a control switch for switching this filter operation is provided, and the above-mentioned control switch is switched off. In other words, the sound reproducing apparatus is characterized in that the frequency characteristic of the reproduced signal is controlled so as to correspond to the above-mentioned noise frequency characteristic. '

2. In the first aspect, the first frequency band is attenuated in the high frequency band and the low frequency band is enhanced so as to correspond to the train noise frequency characteristic and the vehicle noise frequency characteristic, respectively. In addition to providing a second filter, a control switch for switching the operation of the first or the second filter and the non-operation of both the filters is provided. A switch is provided, and by controlling the control switch, control is performed so as to obtain a frequency characteristic of a reproduced signal corresponding to a noise frequency characteristic of a train or a car. A sound reproduction device that features this.

3. Measure the sound leakage frequency band to the outside with the headphone attached, and provide an attenuation filter to attenuate the sound leakage frequency band. A control switch for switching the operation of the attenuation filter is provided, and the switch is turned on and off to turn on the switch. A sound reproducing device characterized by being configured to control sound leakage from the phone to the outside.

4. The frequency of the maximum attenuation level of the attenuation filter according to claim 3. A sound reproducing apparatus characterized in that the number is matched with the frequency of the maximum level in the sound leakage frequency band measured in advance.

In Claim 3, the attenuation filter has a maximum attenuation level of 4 to 8 kHz and an attenuation at 1 kHz, which is the center frequency of the vocals. A sound reproduction device that is characterized by being an attenuating filter that has almost no steep attenuation characteristics.

Predict the noise frequency characteristics obtained by frequency analysis of the amount of noise in the noise environment used, and the frequency band of external sound leakage when the headphone is attached. And an attenuating filter that attenuates the above-mentioned sound leakage frequency band, and an attenuating filter that attenuates the above-mentioned sound leakage frequency band. A control switch for switching the operation of both filters is provided, and by switching the control switch, the frequency characteristic of the reproduced signal is adjusted to the above noise characteristics. An acoustic playback device that is designed to control sound leakage from the headphone to the outside when it is mounted and to be compatible.