WO2011068192A1

WO2011068192A1 - Acoustic conversion device

Info

Publication number: WO2011068192A1
Application number: PCT/JP2010/071659
Authority: WO
Inventors: 淳司渡邊; 杏介坂倉; ゆい川口
Original assignee: 独立行政法人科学技術振興機構
Priority date: 2009-12-03
Filing date: 2010-12-03
Publication date: 2011-06-09
Also published as: JPWO2011068192A1; JP5281695B2

Abstract

The invention attempts to provide a new and unconventional acoustic space; the basic concept is to provide an acoustic space which realizes the movement of sound from inside the human body to outside of the human body, or reversely, from outside of the human body to inside of the human body. A sound output device mountable near the ear is used as the output means for internal sound positioned in the human head, and an externally located sound output device is used as the output means for external sound; the spatial effect of the sound is implemented as the acoustic space between inside and outside of the body. The acoustic conversion device is provided with a sound signal generation device (12), at least one internal sound output device (16) mountable near the ear of a listener, and at least one external sound output device (14) positioned at a distance from the listener. The internal sound output devices and the external sound output devices are capable of simultaneous output, and said devices output different sound information such that the listener can listen to sound from the internal sound output device (16) and the external sound output device (14).

Description

Acoustic transducer

The present invention relates to an acoustic conversion device that converts an audio signal generated by an audio signal reproduction device, and provides a new acoustic space that superimposes a spatial external acoustic effect outside the human body and an internal acoustic effect that is localized inside the human body. The present invention relates to an acoustic conversion device.

With regard to the method of playing sounds from various sound sources including music and natural sounds (hereinafter referred to as “sound”) as well as human voices, the playback range has been expanded to create a more realistic and realistic sound space. Various methods for providing have been proposed.

The simplest method is to output sound from a sound playback device through a single speaker and listen to it. Also, the horizontal position of the sound as used in movies and music playback, etc., can be controlled to the left and right. There is also a method of providing an acoustic space in a stereo system that outputs left and right sounds from two arranged speakers. Furthermore, in order to effectively provide a more realistic sensation, the stereo sound speaker system has two front left and right speakers, two rear left and right speakers, and one center speaker. There is a method of providing a three-dimensional acoustic space by installing a system consisting of a total of five speakers, and further installing a system consisting of a total of six speakers by adding a subwoofer speaker.

The stereophonic sound system has been devised to provide a more realistic and effective sound space by expanding the reproduction range of the sound range by using a plurality of speakers, not just one speaker at the position of each speaker. Furthermore, a technique is also disclosed in which signal processing is performed so that a natural sense of spaciousness and perspective can be obtained by adding an appropriate reflected sound or reverberation sound to the audio signal output from each speaker ( For example, see Patent Documents 1 and 2).

Also, when the listener enjoys personal use by blocking external sounds, he / she wears earphones and headphones. In this case, there is a method of using a binaurally recorded audio signal in order to output a more natural sound to both ears. Binaural recording is a system that records not only the sound that humans listen to directly from the sound source to the left and right ears, but also all the sound waves that are complicatedly diffracted and reflected by the listener's own earlobe and body parts. Then, if the recorded sound is heard in the left and right ears with earphones, the same sound field as that during recording can be felt (see, for example, Patent Document 3).

Recently, mobile terminal devices such as mobile phones, portable music players and portable game machines have become widespread. Since these devices are portable, there are many cases where there is only one built-in speaker due to physical restrictions, and when listening through the built-in speaker, sound is reproduced in monaural. On the other hand, when earphones are used, it is often enjoyed by outputting stereo sound from the left and right earphones (see, for example, Patent Document 4).

Efforts are also being made on a three-dimensional space reproduction system that allows users to experience another space using a video display device that can be visually blocked from the outside world. For example, there is a system comprising a small video display device called HMD (Head Mounted Display) for displaying video, a small video display device that can be attached to the face, a device for outputting audio signals, and a control device for the device. Since it is possible to visually block the outside world and display a three-dimensional image, it is easy to virtually experience other spaces, but the audio output device remains a stereo sound source. (For example, refer patent document 5 etc.).

JP-A-6-189399 JP 2005-184140 A JP 2007-235920 A JP 2009-194932 A JP-A-6-269096

The conventional audio reproduction system has been focused on how to provide a three-dimensional acoustic space and reproduce realistic audio for the listener. It is a three-dimensional acoustic space in a more natural form. These sound reproduction systems have focused on how to effectively transmit external sounds to the ear.

The present invention is a proposal intended to provide a new acoustic space that has not existed before, and the basic concept is that sound is transmitted from the inside of the human body to the outside of the human body, or vice versa. The purpose is to present an acoustic space that achieves the effect of moving inside.

In the present invention, an audio output device that can be worn in the vicinity of the ear is used as an output unit for audio (internal audio) that is localized in the human head, and audio that is externally located is localized (external) By using them together as sound output means, the sound is presented in an acoustic space including the inside and outside of the human body.

The acoustic conversion device according to the present invention includes an audio signal generation device, at least one internal audio output device that can be mounted near the listener's ear, and at least one external audio output device that is located away from the listener. And an audio conversion device that outputs different audio information so that the internal audio output device and the external audio output device can output simultaneously, and listens to the audio from the internal audio output device and the external audio output device.

The audio signal generation device may be a stereo audio reproduction device, an AM / FM radio receiver, or the like, and needs to be an apparatus having at least two audio signal sources of an external audio signal to be reproduced and an internal audio signal. .

The external audio output device specifically uses a speaker. It is an external audio output device because it is an audio source localized outside the listener.

The internal audio output device is specifically realized with earphones or headphones. That is, if it is worn near the ear and the sound is output simultaneously to both ears, the human can listen so that the sound is localized in the head. Therefore, it is heard as sound inside the human body.

Since the internal audio output device is used together with the external audio output device, it does not have a structure that seals the external auditory canal. In addition to the function as the internal audio output device, it is necessary to transmit external audio to the ear drum. . For this reason, an open air type (open type) earphone or headphone is preferable. However, in the open air type, it is not always necessary that the eardrum and the earphone or the outside of the headphones are connected by a gap. For example, the vent may be covered with a cloth or the like. Any function that can transmit external sound to the eardrum is sufficient.

As one of the ideal devices for generating internal sound, there is a bone transmission earphone. A bone transmission earphone is an earphone that directly transmits sound to the auditory nerve by directly applying vibration such as an audio signal to the skull near the ear. In addition to being able to listen to the sound signal from the sound signal generator without being disturbed by external noise, it is possible to keep the ear open, so the external sound coming from the ear while listening to the sound with the bone conduction earphone You can listen to the sound easily.

The connection between the audio signal generating device and the internal audio output device can eliminate complicated wiring cords for wireless communication.

In this way, in addition to the external audio output device, a new acoustic space that has not been available can be provided by using the internal audio output device together with the sound localized in the human body. Of course, the external audio output device is not only a single speaker audio output, but also a three-dimensional sound space in which three speakers and a subwoofer speaker at the front left and right and center of the listener, and speakers at the rear left and right of the listener are arranged. Available. By providing an internal audio output device capable of localizing the sound inside the human body in such a stereophonic sound space, an acoustic space having an unprecedented effect can be realized.

In order to provide a new acoustic space according to the present invention, the sound for the internal audio output device is prepared and the number of channels of the audio signal is increased, but it can also be realized by converting the conventional audio reproduction system device. It is. In a conventional audio signal generating device that generates stereo type two-channel audio signals, either one of the audio signals is simultaneously supplied to the left and right external audio output devices, and the other audio signal is supplied to the internal audio output device. Supply. As a result, the left and right acoustic spaces outside the listener are converted into acoustic spaces outside and inside the listener, and sound can be heard in an acoustic space different from the conventional one.

Furthermore, the audio signal generating device may generate three or more audio signals and supply at least one or two audio signals among the plurality of audio signals to the internal audio output device. For example, it is realized by supplying at least one or two audio signals to an internal audio output device among a plurality of audio signals that generate audio signals to the left and right speakers in front of the listener and the center speaker and the left and right speakers behind the listener. May be. That is, it is an acoustic conversion device that can listen to one or two audio signals of audio signals from a plurality of sound sources provided in a conventional audio generating device as audio signals to earphones or headphones. .

Conventionally, in a portable device such as a mobile phone, a radio receiver, a music player, or a game machine, when listening to sound, it is listened with a built-in speaker, or an earphone or headphone connection cord is inserted into an earphone plug, or a sound output device. It is common to listen by switching. The present invention can also be applied to such portable devices. Switching unit so that one audio signal can be output from the earphone or headphones and the other audio can be output from the built-in speaker when a connection cord is inserted into the earphone plug in order to provide an acoustic space by external sound and internal sound This can be realized by making it possible to switch.

The external audio output device and the internal audio output device have different sound reproduction characteristics. For example, external sound from a speaker includes reverberation in the environment, and delay due to sound propagation time from the speaker to the listener also occurs. The sound reproduction range is also different as seen in the frequency characteristics depending on the output device.To match the sound quality of the presented sound, the reverberation effect that approximates the external sound or the external sound is added to the sound signal sent to the internal sound output device. It is also effective to correct a signal such as a delay in accordance with the propagation time.

In order to match the frequency characteristics of the external audio output device and the internal audio output device, a low-pass filter is installed on the one with good audio reproducibility to cut the high frequency range, and the audio from other audio output devices Consistency with the reproduction range may be taken. The internal audio output device is specifically an earphone or a headphone, and the external output device is a speaker. The frequency characteristics are determined depending on the device. Therefore, a low-pass filter is provided on one side, and the cut-off frequency is variable, so that the frequency reproduction range between the external audio output device and the internal audio output device can be adjusted.

イ Earphones and headphones are small devices, and bass reproducibility is generally inferior compared to speakers. For this reason, the low-frequency region of the internal audio signal to the internal audio output device is taken out by the internal audio low-pass filter, the signal is added to the external audio output device, and a part of the internal audio is output from the external audio output device. Output. When matched to the frequency characteristics of earphones, etc., the external sound (especially in the low frequency region) will be greatly degraded. However, this operation can compensate for the low frequency region that cannot be reproduced by the earphone of the internal sound signal with the external sound. . The cut-off frequency of the internal audio low-pass filter is adjusted according to the characteristics of the low-frequency region that cannot be reproduced by the internal audio output device. In addition, signal processing for perspective is effective for localization within the human body. And then output from the speaker to share the function as internal sound.

The audio signal generation device can also be provided with an output screen for image information including moving images. In this case, the sound that uses the output screen as a sound source is output from the external audio output device, and the sound of the announcer on the output screen By outputting sound that does not use the output screen of the commentator's voice as a sound source from the internal audio output device, an effective acoustic space integrated with the output screen announcer and commentator can be provided. In some cases, reversely, the sound that uses the output screen as the sound source is output from the internal audio output device, and the sound that does not use the output screen as the sound of the announcer or commentator on the output screen is output from the external audio output device. By outputting, you can also expect the effect of creating a sense of unity with the screen.

When the audio signal generator is a 3D television, a powerful acoustic space from the outside of the human body to the inside of the human body can be realized along with the stereoscopic effect of the image.

In recent years, the development of digital technology and video display technology has been remarkable, and a three-dimensional space reproduction system that cuts off the outside and vision has been proposed. For example, it is a head-mounted display called HMD (Head Mounted Display). The HMD is mounted on the head, and a small video display device is arranged on the face, and audio is output by the audio output device. An external audio output device and an internal audio output device can be configured by headphones or the like worn on the human body, and a three-dimensional acoustic space that has not been available in the past can be provided.

According to the acoustic conversion device of the present invention, in addition to the sound output device in which the sound is localized outside the listener, the sound conversion device includes an internal sound output device localized in the listener, so that a new acoustic space can be realized. An unprecedented sound effect can be obtained. Also, in an existing audio reproduction system, a completely different acoustic effect can be realized by distributing a plurality of audio output signals to an external audio output device and an internal audio output device.

1 is a basic schematic diagram of an acoustic transducer device according to the present invention. The block diagram of the concrete acoustic converter by an audio | voice signal generator, one external audio | voice output apparatus, and one internal audio | voice output apparatus. The concrete conceptual diagram using the acoustic converter by one external audio | voice output apparatus and one internal audio | voice output apparatus. The block diagram of the acoustic converter provided with the external audio | voice output apparatus of 2 channels and the internal audio output apparatus of 2 channels to which this invention is applied. The concrete conceptual diagram using the acoustic converter provided with the external audio | voice output apparatus of 2 channels, and the internal audio | voice output apparatus of 2 channels. The block diagram of the acoustic converter provided with the external output apparatus which has a several sound source and which comprises this invention, and comprises a stereophonic sound space, and the internal audio output apparatus of 2 channels. The concrete conceptual diagram using the acoustic converter provided with the external output apparatus which has a some sound source, and comprises the stereophonic sound space, and the internal audio output apparatus of 2 channels. The block diagram of the conventional stereo system which has a 2-channel audio | voice output apparatus. The block diagram of the acoustic converter which supplied one audio | voice to the headphones with respect to the conventional stereo system which has a two-channel audio | voice output apparatus. The block diagram of the acoustic converter which output the audio | voice output of back 2 channel to the headphones on either side among the audio | voice outputs in the stereophonic sound space which arrange | positions audio | voice output apparatuses ahead and back conventionally. An example of frequency characteristics of an earphone and a speaker. The block diagram at the time of providing the low-pass filter, signal processing part, and signal correction | amendment part for making the audio | voice output from a speaker and the characteristic of an earphone match. The block diagram of the acoustic converter by this invention using a mobile telephone. The example using the acoustic converter by this invention using a mobile telephone. The example of the acoustic converter by this invention using a head mounted display.

Hereinafter, embodiments of an acoustic conversion device of the present invention will be described in detail with reference to the drawings.

Example 1
FIG. 1 is a basic block diagram of an acoustic transducer 10 according to the present invention. The audio signal generator 12, the external audio output device 14, and the internal audio output device 16 are included. Here, the audio signal generation device 12 is, for example, a CD (Compact Disk) player, an FM (Frequency Modulation) radio receiver, or the like, and generates an audio signal of one channel or more to each of the external audio output device and the internal audio output device. Equipment. The external audio output device 14 is a speaker, and is an audio output source arranged at a position away from the listener. The internal audio output device 16 is an output device in which sound is localized inside the human body, particularly inside the head, and uses earphones, headphones, and the like. The earphones and headphones may be wireless. Bone conduction earphones and headphones can also be used.

As an audio reproduction method by the external audio output device 14, a simple monaural reproduction method including one speaker, a stereo reproduction method for reproducing an audio signal of two channels, a multi-speaker reproduction method for providing a three-dimensional sound space, and the like. There is.

The monaural playback system is used in low-cost devices as a simple audio playback system. The stereo reproduction method is presented with a volume level difference or a time difference between the two channels. In order to produce a spatial acoustic effect, there is a case in which an extension is performed in which the sound pressure felt by the ear is subjected to sound signal processing by a head-related transfer function, for example, and the sound direction is arbitrarily localized. The multi-speaker playback method for a three-dimensional acoustic space with a multi-speaker generally has a left speaker, a right speaker and a center speaker arranged in front of a listener, and a left rear speaker and a rear part of the listener. A right rear speaker is arranged to provide a three-dimensional acoustic space.

Conventionally, the provision of a three-dimensional acoustic space has been an acoustic space consisting only of speakers as an external audio output source, or an acoustic space consisting only of internal audio output sources such as earphones and headphones as an audio output source from the vicinity of the ear. On the other hand, the acoustic space according to the present invention is characterized by using an external audio output source and an internal audio output source at the same time to localize sound both outside and inside the human body. It is to provide.

In the present invention, since it is necessary to listen to the external sound from the speaker and the internal sound from the earphone or the headphones at the same time, it is desirable that the earphone or the headphones is an open air type device. And it is more effective if it is a bone conduction earphone whose ears are completely opened.

FIG. 2 is a block diagram specifically showing an acoustic conversion apparatus according to the present invention when the external audio output and the internal audio output are in a monaural reproduction system in order to explain the present invention more specifically. The audio signal generation device 12 inputs audio through the audio input unit 20. The input method may be any method other than microphone input as long as audio input is possible such as audio cassette tape, CD, DVD (Digital Video Disk), Blu-ray Disc. The storage unit 22 stores the input audio signal. The audio signal processing circuit 24 is a circuit for encoding and decoding audio data. The output signal processing unit 26 performs processing corresponding to each output device on the audio output signal. An external audio signal is amplified by the amplifier 28 and output from the speaker 30. The internal audio signal is output from the headphones 32 and the sound source is localized in the head.

FIG. 3 is a specific conceptual diagram of the present invention for a case where the external audio output and the internal audio output are monaural reproduction systems. An audio signal for external audio output and an audio signal for internal audio output are supplied from the audio signal generator 12. The listener can configure a new acoustic space by wearing the headphones 32 and listening to the internal sound, and further adding the external sound from the speaker 30 and listening simultaneously.

FIG. 4 is a block diagram specifically showing an acoustic conversion apparatus according to the present invention when the external audio output and the internal audio output are in a stereo reproduction system. The amplifier 28 includes an amplifier R28-1 and an amplifier L28-2 corresponding to the left and right speakers 30 of the listener, and external sound is output from the speaker R30-1 and the speaker L30-2. Also, the stereo internal sound is simultaneously heard from the headphones R32-1 and L32-2.

FIG. 5 is a specific conceptual diagram of the acoustic conversion device according to the present invention when the external audio output and the internal audio output are in a stereo reproduction system. In this case, the headphones 32 are attached to the left and right with respect to the two-channel audio signal, so that the user can experience a more realistic sound space than the case shown in FIG.

FIG. 6 is a block diagram specifically showing an acoustic conversion device provided with an internal audio output device in addition to a sound reproduction method having a three-dimensional sound space effect using a large number of speakers. The output signal processing unit 26 performs signal processing for expressing a three-dimensional sound effect.

５ Five amplifiers 28-1 to 28-5 are used to amplify the audio to the external audio output device. In the amplifier 28, each amplifier is connected to five speakers 30-1 to 30-5. The speaker 30 includes a speaker R30-1 disposed at the front right side of the listener, a speaker C30-3 disposed at the front center, a speaker L30-2 disposed at the front left side, a speaker RR30-4 disposed at the rear right side, and the rear left side And the speaker RL30-5 disposed in the.

Furthermore, headphones 32 are used for internal audio output. Headphone 32 is attached to headphone R32-1 on the right ear and headphone L32-2 on the left ear corresponding to the left and right ears.

FIG. 7 is a specific conceptual diagram of the three-dimensional acoustic space according to the present invention described in FIG. Such an acoustic space generates an acoustic effect from the outside and inside of the human body, so that it is possible to experience an acoustic space with a new and powerful presence that has never existed before.

(Example 2)
In the first embodiment, it is necessary to newly input an input signal for internal voice in addition to the conventional voice input. However, the present invention can be realized even if a conventional voice signal is used. .

FIG. 8 shows an audio playback device using a conventional stereo playback system. The audio input unit 20 receives 2-channel audio signals corresponding to the left and right audio output devices. An audio signal may be stored in the storage unit 22. The input audio signal is subjected to signal processing by the signal processing unit 24 and the output signal processing unit 26. In the case of external audio output, the audio amplified by the amplifier R28-1 is output from the speaker R30-1 on the right side of the listener. The left speaker L30-2 outputs the sound amplified by the amplifier L28-2. In the speaker 30 and the headphone 32, when the headphone plug 31 is inserted into the jack 33, the switching unit 27 operates in conjunction with the output signal so that the output signal is an R side jack line 29-1 and an L side jack line 29-2 to the headphone 32 side. Configured to connect to.

FIG. 9 is a block diagram showing an example in which the present invention is applied using a stereo reproduction type audio signal. In the present invention, for example, the switching unit 27 can switch the right audio signal from the speaker 30 and the left audio signal from the headphones 32. In FIG. 9, the left audio signal line and the right audio signal line for external audio output are connected together, the right audio signal flows to the left amplifier L28-2, and the right audio signal amplified also to the speaker L30-2. Is supplied. At this time, the same left audio signal flows through the R side jack line 29-1 and the L side jack line 29-2 of the headphones 32.

Conventionally, the acoustic space is such that the left and right audio signals are output only with the speakers or only with the headphones, but by switching the switching unit 27 so that one audio signal is output from the speaker 30 and the other audio signal is output from the headphones 32. New acoustic space can be provided.

(Example 3)
The new acoustic space according to the present invention can be applied to a multi-speaker reproduction system using a conventional audio signal.

FIG. 10 is a block diagram when the present invention is applied to a three-dimensional acoustic space provided by a plurality of speakers. Conventionally, the audio signal supplied from the output signal processing unit 26 includes a front right speaker R30-1, a front center speaker C30-3, a front left speaker L30-2, a rear right speaker RR30-4, and a rear left side. Speaker RL30-5, and when listening through the headphones 32, the sound is output by being integrated into two channels. The present invention supplies the audio signal supplied to the rear speaker RR30-4 and the rear speaker RL30-5 among the five-channel audio signals supplied to the speaker 30 to the headphone R32-1 and the headphone 32-2. To realize a new acoustic space. Audio signals supplied to the speakers RR30-4 and RL30-5 are switched before the amplifiers RR28-4 and RL28-5, and the signal lines are connected to the headphones R32-1 and L32-2. As a result, a new sound is generated by the external audio output composed of the speaker R30-1, the speaker C30-3 and the speaker L30-2 and the internal audio output composed of the headphone R32-1 and the headphone L32-2. A space is constructed.

Of course, as the internal output sound, other sound sources, that is, sound sources from the speaker R30-1, the speaker C30-3, and the speaker L30-2 may be used.

Example 4
In the present invention, an external audio output device and an internal audio output device are used. Specifically, the external audio output device is a speaker, and the internal audio output device is a headphone, an earphone, a bone conduction earphone, or the like. It is. However, there are cases where the speaker and the earphone are different in the reproduction range of the audio output, particularly in the frequency characteristics, and the audio output is not matched and it is necessary to process the audio signal.

FIG. 11 is an example of the frequency reproduction range 34 of the speaker and the earphone. In FIG. 11, the frequency characteristic 36 of the speaker shows a relatively flat response from a low frequency region to a high frequency region, and is usually in a range of about 10 Hz to 20 kHz. The frequency characteristic 38 of the earphone has a low response characteristic in a low frequency region of 200 Hz or less and a high frequency region of 5 kHz or more. Since the earphone is structurally small, it is difficult to reproduce in the low frequency region, and the response characteristic is generally inferior to the speaker even in the high frequency region. Of course, there are various characteristics depending on the earphone model, but it is inevitable that the sound quality will be different due to the difference from the speaker.

In the present invention, it is considered that the external sound and the internal sound can be heard without a sense of incongruity by matching the characteristics of the speaker and the earphone. For this purpose, first, in the high frequency region, the audio signal supplied to the speaker is cut in accordance with the frequency characteristics of the earphone. In the example of FIG. 11, the responsiveness of the earphone is lowered when it exceeds about 5 kHz. In order to match the characteristics of the earphone and the speaker, a low-pass filter having a cutoff frequency of 5 kHz is provided in the audio signal supplied to the speaker. Although the sound quality from the speaker is degraded, the sound quality matched with the earphone allows a natural sense of listening.

Next, in the example of FIG. 11, the response characteristics of the low frequency region are degraded at about 200 Hz or less. In this case, the frequency characteristics of the speaker may be cut to a frequency region of 200 Hz or less to match the sound quality. However, when the high frequency and the low frequency are cut, the sound quality is further deteriorated. Since low-frequency sound has a sensation of reverberating throughout the body, the sound signal supplied to the earphone is branched into a speaker sound for external sound through a low-pass filter that extracts a frequency component of 200 Hz or less. Superimpose. As a result, the low frequency region of the audio signal supplied to the earphone is reproduced, but it is an internal audio signal, and is subjected to signal processing that gives a sense of perspective and is superimposed on the external audio.

FIG. 12 is an example applied to the two-speaker stereo reproduction system shown in FIG. 4, and a low-pass filter A40 for cutting a high-frequency region is provided in the audio signal to the speaker 30. Further, in order to cover the low frequency region that deteriorates due to the earphone characteristics, the audio signal to the earphone is branched, the low frequency region is taken out, and the speaker 30 is connected via the low-pass filter B42 and the signal processing unit 44. Are superimposed on the amplifier 28 and output.

The external audio signal supplied from the output signal processing unit 26 to the speaker R30-1 passes through the low-pass filter A40-1 having a cutoff frequency of 5 kHz, for example, in accordance with the characteristics of the earphone 46, and then the amplifier R28- 1 is amplified. Similarly, a low-pass filter A40-2 is provided for the signal supplied to the speaker L30-3. The cut-off frequency of the low-pass filter A40 can be arbitrarily adjusted in accordance with the frequency response characteristics of the earphone 46, so that the earphone model can be changed.

In order to cover the low frequency region reproducibility, the internal audio signal to the earphone 46 is branched into the internal audio signal to the earphone R46-1 and the earphone L46-2, and the cut-off frequency is set to 200 Hz respectively. Internal audio low-pass filters B42-1 and 42-2 are provided. The internal sound low-pass filters B42-1 and 42-2 here are for extracting signal components in the low-frequency region of the internal sound signals output from the earphones 46-1 and 46-2, and the signal processing unit The signal is superimposed on the external audio signal for the speaker 30 via 44-1 and 44-2. The signal processing unit 44 of the internal audio signal performs processing such as reducing the reverberation effect so that an audio effect similar to the internal audio output can be obtained.

Furthermore, there is an acoustic spatial difference between the external sound and the internal sound when the listener listens. For example, the external sound is unavoidably accompanied by a reverberation effect from the surroundings and a delay due to the sound propagation time from the speaker that physically outputs the external sound to the listener. For this purpose, signal correcting sections 48-1 and 48-2 are provided for the internal audio signal, and signals with at least reverberation effect added and time delay processing are sent to the earphones 46-1 and 46-2. The processing in the signal correction unit 48 is not limited to the reverberation effect and the time delay, and other processing may be performed.

By correcting the external audio signal and the internal audio signal as described above, it is possible to reduce differences in the characteristics and acoustic space of the output device.

(Example 5)
The audio signal generation device is not limited to audio, and may be provided with an image display as visual information. For example, there are television screens, DVD playback screens with image output, and recently, three-dimensional video display devices. Moreover, there are a mobile phone, a music player, a game machine, etc. as portable mobile terminals, and the present invention is applicable to any case. On TV screens and DVD playback screens, moving the sound from the speaker to the earphone, especially the sound of water flowing from the faucet, moves the body into the water. Feel like. Moreover, if the sound of human beings, such as the sound of the heart and breathing, is transferred from the earphone to the speaker, an effect that the consciousness is easily directed outward is produced.

For example, when the output screen is a live broadcast of baseball or soccer, the sound that does not use the output screen such as the announcer's voice or the commentator's voice is output from the earphone, and the atmosphere of the stadium or ballpark is passed through the sound collection microphone. By outputting from the speaker, a more realistic sound space can be provided.

(Example 6)
The present invention can be easily applied to mobile terminals such as mobile phones and music players.

FIG. 13 is a block diagram of the case where the present invention is applied to the mobile phone 50. The CPU 52 controls the operation of the mobile phone 50 according to a control program installed in the storage unit 54. The storage unit 54 is a nonvolatile memory such as a flash memory. The recording medium 56 is a removable memory such as a removable smart media, and supplies image data, various data, programs, and the like from the outside. The memory 58 is an internal memory having a work area, and is composed of, for example, a DRAM (Dynamic Random Access Memory).

The telephone communication unit 62 to which the antenna 60 constituting the radio unit is connected takes in the signal from the receiving side and demodulates it, then gives this audio signal to the acoustic control unit 74 and outputs it from the reception speaker 78. When enjoying music such as a music file, sound is output from the built-in speaker 80, or output from the left and right portable earphones R82-1 and L82-2 via the switching unit 84. The audio signal is monaural when output from the built-in speaker 80, and becomes two-channel stereo sound when output from the portable earphone. This control is performed by the acoustic control unit 74. Also, the audio information is transmitted by taking the audio signal input from the audio microphone 76 from the acoustic control unit 74 and transmitting it from the telephone communication unit 62 through the antenna 60.

The main display unit 66 is a liquid crystal display device or the like that displays character information and various messages controlled by the image control unit 64 with high quality. The sub display unit 68 provided on the back side of the apparatus main body is Display date and time, simple messages, icons, etc. The key operation unit 70 performs numeric input, character input, command input, and the like. A key for instructing the start of a telephone call, a key for instructing the end of a telephone call, a reproduction key for instructing a reproduction output of a music file / recording file, etc. have.

The portable earphone R82-1 and portable earphone L82-2 that are worn on the left and right ears are connected to the main body of the mobile phone 50 by inserting an earphone plug into the switching unit 84 and used for playing music files, etc. To do. When a music file is played back without connecting the portable earphone R82-1 and the portable earphone L82-2, sound is output from the built-in speaker 80. When a telephone call start operation is performed while voice is being output from the built-in speaker 80, the portable earphone R82-1, or the portable earphone L82-2, the output destination of the received voice is sent to the reception speaker 78. When switching or telephone call termination operation is performed, the output destination is again returned to the built-in speaker 80, the portable earphone R82-1, and the portable earphone 82-2.

The present invention is applied when a mobile phone is mainly used as an output device for audio signals such as music files, and a specific embodiment is shown in FIG. When listening to music from the built-in speaker 80, the sound is monaural, and when listening through the portable earphone R82-1 and the portable earphone L82-2, the sound is stereo. Switching between the normally used mode and the use mode according to the present invention in this case is manually performed by the switching unit operation button 86. In the use mode according to the present invention, one of the left and right stereo sounds is output as an external sound from the built-in speaker 80, and the other stereo sound is connected to the portable earphone R82-1 and the portable earphone L82-2 to supply an audio signal. To do. Recently, there is a mobile terminal provided with two speakers to reproduce stereo sound even with a built-in speaker, but the present invention can be applied even in such a case. In any case, a two-channel audio information source to the built-in speaker or the portable earphone is sufficient.

As described above, the mobile terminal such as a mobile phone can also provide the acoustic space according to the present invention, and can enjoy a new acoustic space that could not be experienced in the past.

(Example 7)
The present invention is particularly effective when applied to a 3D television or a head mounted display (HMD) which is a head mounted display.

FIG. 15 shows a specific example in which the present invention is applied when the head-mounted display 90 is used. The head-mounted display 90 is a three-dimensional space reproduction system using video and sound. The basic configuration includes a display device 92 for the left and right eyes and an HMD headphone 94 for outputting audio signals to the left and right ears. The control unit (not shown) includes a video signal source, a depth signal generator, a high-speed phase modulator, an acoustic signal generator, a reverberation synthesis circuit, and the like. This is a system that presents a virtual three-dimensional space by blocking the field of view from the outside, using an HMD speaker 98 as an audio output device, connected to the head-mounted display 90 with a connection cord 96, and an HMD headphone 94. It can be realized by using it together (however, the connection between the head mounted display 90 and the HMD speaker 98 may be wireless). Along with the three-dimensional display screen, an acoustic effect from the inside of the human body to the outside, or conversely, from the outside to the inside of the human body, makes it possible to feel an unprecedented presence.

Although the embodiments of the present invention have been described above, the present invention includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited by the above embodiments.

Claims

An audio signal generator,
At least one internal audio output device that can be worn near the listener's ear;
At least one external audio output device remote from the listener;
With
Outputting different audio information as being capable of simultaneously outputting the internal audio output device and the external audio output device, and listening to audio from the internal audio output device and the external audio output device;
An acoustic transducer characterized by the above.
In the scope of claim 1,
The external audio output device is a speaker;
An acoustic transducer characterized by the above.
In the scope of claim 1 or claim 2,
The internal audio output device is an earphone or a headphone;
An acoustic transducer characterized by the above.
In the scope of claim 3,
The earphone or the headphone is an open air type,
An acoustic transducer characterized by the above.
In the scope of claim 1 or claim 2,
The internal audio output device is a bone conduction earphone;
An acoustic transducer characterized by the above.
In the range in any one of Claims 3-5,
The internal audio output device is a wireless type;
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-6,
The audio signal generator generates two stereotype audio signals, supplies one of the audio signals to an external audio output device, and supplies the other audio signal to the internal audio output device;
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-6,
The audio signal generator generates three or more audio signals,
Supplying at least one or two of the plurality of audio signals to the internal audio output device;
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-6,
The external audio output device is integrally incorporated in the audio signal generation device as a monaural type or stereo type audio output device, and when the earphone or headphone plug is inserted into the audio signal generation device to listen to the audio, the stereo type The left and right audio signals are output from the external audio output device incorporating the left and right audio signals, and the other one is output from the left and right internal audio output devices. An acoustic transducer characterized by the above.
In the scope of claim 9,
The audio output device in which the external audio output device is integrally incorporated in the audio signal generating device is a portable device,
An acoustic transducer characterized by the above.
In the scope of claim 10,
The portable device is a mobile phone, a radio receiver, a music player or a game machine;
An acoustic transducer characterized by the above.
In the range of either claim 10 or claim 11,
Providing a switching unit capable of switching one audio signal of a stereo type audio signal supplied to the internal audio output device to the external audio output device;
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-12,
Having a signal correction unit that corrects at least the reverberation effect of external audio output and the delay time of audio propagation to the listener with respect to the audio signal to the internal audio output device;
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-13,
In order to match the characteristics of the external audio output device and the internal audio output device in the high frequency range, a low-pass filter is provided in one of the audio signal circuit supplied to the external audio output device or the internal audio output device. Having
An acoustic transducer characterized by the above.
In the scope of claim 14,
The cut-off frequency of the low-pass filter is variable and can be adjusted to balance the sound reproduction range between the external audio output device and the internal audio output device,
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-14,
In order to have the audio signal supplied to the internal audio output device output from the external audio output device a low frequency region whose reproduction characteristics are degraded depending on the performance of the internal audio output device, the external audio output device, Adding the low frequency signal that has passed through the internal audio signal low-pass filter,
An acoustic transducer characterized by the above.
In the scope of claim 16,
A signal processing unit for making the cut-off frequency in the low frequency region of the internal audio low-pass filter variable and further approximating the audio signal that has passed through the internal audio low-pass filter to the internal audio;
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-6,
The audio signal generating device includes an output screen for image information including moving images,
The sound using the output screen as a sound source is output from the external audio output device,
Outputting from the internal audio output device audio that does not use the output screen as a sound source, such as the voice of the announcer of the output screen and the voice of the commentator,
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-6,
The audio signal generating device includes an output screen for image information including moving images,
The sound having the output screen as a sound source is output from the internal audio output device,
Outputting from the external audio output device audio that does not use the output screen as a sound source, such as the voice of the announcer on the output screen and the voice of the commentator,
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-6,
The audio signal generating device is a stereoscopic television;
An acoustic transducer characterized by the above.
In the range in any one of Claims 1-6,
The audio signal generating device includes a head-mounted display;
An acoustic transducer characterized by the above.