JP2012248964A - Sound reproduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound reproduction device capable of avoiding risk of accidents and others in doing exercises such as jogging and cycling while wearing an earphone.SOLUTION: In a sound reproduction device, sound pick-up parts 13 and 14 of an earphone 10 pick up a sound emitted from a movable body M that approaches from behind to a user P who is taking a jog. An extraction part 24 of a portable music player 20 analyzes a temporal gradient for a sound signal X in the sound picked up by the sound pick-up parts 13 and 14. A reproduction control part 25 turns down the level of a sound signal Z supplied from a reproduction part 22 to a sound emission part 17 of the earphone 10 when the temporal gradient of the sound signal X analyzed by the extraction part 24 becomes equal to or more than a threshold value TH2.

Description

  The present invention relates to a technique for ensuring the safety of a person who exercises while listening to music with an earphone.

  With the spread of thinner and lighter portable music players, more and more users are hoping to enjoy jogging and other activities while listening to their favorite music. In order to meet such user demands, sealed earphones such as canal earphones that have excellent adhesion to the ears and do not fall off the ears during jogging are provided.

JP 2006-96070 A JP 58-150314 A JP-A-8-2339

  By the way, when performing exercises such as jogging or cycling while wearing earphones such as canal-type earphones on the outdoor road, if the user wears the earphone to the back of the ear, the user approaches from the back toward the user. There is a problem that it is difficult to avoid the danger such as an accident because the listening to the sound of the coming vehicle is hindered.

  The present invention has been devised under such a background, and an object of the present invention is to provide a technical means capable of avoiding dangers such as accidents when wearing earphones and performing exercises such as jogging and cycling. And

  The present invention includes a sound emitting unit that emits a sound signal as a sound in an ear, a sound collecting unit that collects a sound outside the ear, and the sound emitting unit as a sound signal of a specified level. And a reproduction control unit that controls the reproduction level of the sound signal supplied to the sound emitting unit when the time gradient of the volume of the sound collected by the sound collecting unit exceeds a threshold value. Provided is a sound reproducing device.

  In the present invention, when a car or motorcycle is approaching from behind while jogging while listening to music with the sound reproducing device attached, the sound emitted from the car or motorcycle is collected by the sound collection unit. Is done. Then, the reproduction control unit reduces the reproduction level of the input signal of the sound emitting unit when the time gradient of the volume of the sound outside the ear becomes equal to or greater than the threshold value. Therefore, in the present invention, when the moving body behind the user approaches the moving body at a certain speed, the volume of the sound emitted in the user's ear is reduced. Therefore, according to the present invention, it is possible to inform the user that the moving body is approaching from behind and to take a risk avoiding action such as approaching the end of the road.

  Here, Patent Documents 1 to 3 are documents relating to a technique for controlling the volume of music playback for the purpose of traffic safety and the like. In the technique disclosed in Patent Document 1, when music is played in a car, sound outside the car is picked up by a microphone, and the sound volume outside the car exceeds a threshold value or the waveform of this sound is pulsed. The volume of the music is reduced.

  In the technique disclosed in Patent Document 2, in order to notify the user in the vehicle that an emergency vehicle is approaching, noise outside the vehicle is collected by a microphone, and the volume of the collected external noise becomes equal to or higher than a predetermined value. If it is equal to or greater than a predetermined value even after a lapse of time, the volume of music playback in the vehicle is reduced.

  The technology disclosed in Patent Document 3 is such that sounds useful for users in the vehicle, such as police car sirens and railroad crossing warning sounds, are registered in advance, and the registered sounds are collected by a microphone that collects sounds outside the vehicle. When the sound is picked up, the volume of music playback in the vehicle is reduced.

  The techniques disclosed in Patent Documents 1 to 3 above are considered to be useful for protecting a user riding in an automobile from danger. However, as in the present invention, the earphones are used for jogging or the like. When a car or the like is approaching a person, the user is not informed of the danger of approaching the car and is not protected from the danger.

It is a figure which shows the structure of the sound reproduction apparatus which is one Embodiment of this invention. It is a figure which shows the state which mounted | wore the user's ear with the headphones of the apparatus. It is a figure for demonstrating that the sound collection means which has a directivity axis in the front and back of a user is implement | achieved by the two sound collection parts and subtraction parts in the same apparatus. It is a figure which shows control of the level of the sound signal by the reproduction | regeneration control part of the apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a sound reproducing device 1 according to an embodiment of the present invention. In the sound reproduction device 1, when a car C or a motorcycle B (hereinafter, the automobile C and the motorcycle B are collectively referred to as a “moving body M” as appropriate) is approaching from behind the user P who is jogging while listening to music. In addition, the volume of the sound to be heard by the user P is changed according to the degree of proximity of the moving body M, and the user P is alerted. The sound reproducing device 1 includes a pair of earphones 10 for right and left ears and a portable music player 20. In FIG. 1, the illustration of the earphone 10 for the left ear is omitted. Each earphone 10 is attached to each ear of the user P. The portable music player 20 is carried by the user P by raising the neck strap 90 connected to the portable music player 20 from the neck of the user P. Earphone 10 and portable music player 20 are connected by a cable 50.

  The earphone 10 is provided with two sound collecting portions 13 and 14 on one end surface 12 on the side of the main body 11, and an insertion portion 16 from a position on the other side 15 of the main body 11 on the back side of the sound collecting portion 13. And a sound emitting portion 17 is provided at the distal end of the insertion portion 16. The sound collecting parts 13 and 14 in the earphone 10 are separated along the extending direction of the main body part 11 (the direction from the back of the head toward the face), and the sound collecting parts 13 and 14 have a distance D1. As shown in FIG. 2, the earphone 10 is attached to the ear of the user P by inserting the insertion portion 16 protruding from the end surface 15 of the main body portion 11 into the ear canal EAC of the ear of the user P. Usually, the earphone 10 is worn on the ear of the user P in such a posture that the two sound collection units 13 and 14 are arranged in parallel with the front-rear direction of the user P (the direction of the bidirectional arrow in FIG. 1).

  In this normal wearing state, the sound collection units 13 and 14 in the earphone 10 collect sound outside the ear of the user P, and the sound signals X1 and X2 of the sound collected by each of the sound are collected via the cable 50. Output to the portable music player 20. The sound emitting unit 17 in the earphone 10 emits the sound signal Z supplied from the portable music player 20 via the cable 50 to the sound emitting unit 17 as a sound in the ear.

In FIG. 1, the portable music player 20 includes a storage unit 21, a playback unit 22, a subtraction unit 23, an extraction unit 24, and a playback control unit 25. The storage unit 21 includes MP3 (MPEG Audio Layer-3) and AAC (Advanced Audio
Various audio files encoded with music formats such as Coding) are stored. The playback unit 22 decodes the audio file in the storage unit 21, and supplies the decoded sound signal as the sound signal Z having the playback level LEV specified by the playback control unit 25 to the sound emitting unit 17 of the earphone 10. To do. Details of the control of the reproduction level LEV of the sound signal Z by the reproduction control unit 25 will be described later.

  The subtracting unit 23 receives the sound signals X1 and X2 output from the sound collecting units 13 and 14 of the earphone 10, subtracts the sound signal X2 from the sound signal X1, and outputs the subtraction result as the sound signal X. Here, in the normal wearing state described above, the subtracting unit 23 and the sound collecting units 13 and 14 of the earphone 10 function as a bi-directional sound collecting unit having directional axes in front and rear of the user P. . The reason is as follows. As shown in FIG. 3, the direction from the sound collection unit 13 to the sound collection unit 14 in the normal wearing state (in front of the user P) is a reference direction, and the direction of the sound source AS viewed from the user P's ear and the reference If the angle formed by the direction is θ (0 ≦ θ ≦ 180), the propagation distance of the sound from the sound source AS to the sound collection unit 13 in the direction near θ = 90 degrees (that is, the direction directly beside the user P) is The sound propagation distance to the sound collection unit 14 is substantially the same. Therefore, in this case, the output signal X1 of the sound collection unit 13 and the output signal X2 of the sound collection unit 14 are substantially in phase and level, and the level of the output signal X of the subtraction unit 23 is substantially zero. However, if the direction of the sound source AS viewed from the user P is greatly deviated from the direction of θ = 90 degrees, the sound propagation distance from the sound source AS to the sound collection unit 13 and the sound propagation distance to the sound collection unit 14 A large distance difference ΔL is generated between them, and a phase difference Δφ corresponding to the distance difference ΔL is generated between the output signal X1 of the sound collection unit 13 and the output signal X2 of the sound collection unit 14. For this reason, when paying attention to the entire band of the sound to be collected, the direction of the sound source AS viewed from the ear of the user P is shifted from the direction of θ = 90 degrees toward θ = 0 degrees and 180 degrees. Accordingly, the level of the output signal X of the subtracting unit 23 tends to increase. For the above reasons, the sound collecting units 13 and 14 and the subtracting unit 23 as a whole are bi-directional sound collecting having a directivity axis in front (θ = 0 degrees) and rear (θ = 180 degrees) of the user P. It will function as a means.

In FIG. 1, the extraction unit 24 extracts a signal having an acoustic feature corresponding to the emission sound (engine sound, tire noise, etc.) of the car C or the motorcycle B in the waveform indicated by the output signal X of the subtraction unit 23. A time gradient of the volume of the sound represented by the extracted signal is obtained, and the time gradient is compared with the threshold value TH1. In more detail, the extraction unit 24, BPF (Band Pass Filter) processing and release sound motorcycle B to release sound of the car C is a band W _C passband belonging to the output signal X from the subtraction portion 23 is subjected to the BPF processing for the pass band belongs band W _B individually to determine whether passage components pass component or band W _B of the band W _C exceeds the threshold value TH1. The extraction unit 24 performs the following processing when the passing components pass component or band W _B of the band W _C exceeds the threshold value TH1.
a1. In this case when the passing components of band W _C exceeds the threshold value TH1, extractor 24 considers that there is an automobile C traveling within a predetermined distance range at the rear of the user P. Extractor 24, a sound collection signal of the sound emission of the output signal X from the subtraction portion 23 car C between the passage component band W _C is greater than the threshold value TH1 to below the threshold TH1, during which the subtraction unit 23 The time gradient (differential value) of the output signal X is calculated. The extraction unit 24 outputs this time gradient as a signal Y indicating the speed of the vehicle C approaching the user P.
a2. In this case when the passing components of the band W _B exceeds the threshold TH1, the extraction unit 24, regarded as there are bike B traveling within a predetermined distance range at the rear of the user P. Extractor 24, a sound collection signal of the sound emission bike B output signal X from the subtraction portion 23 between the passage component band W _B is greater than the threshold value TH1 to below the threshold TH1, during which the subtraction unit 23 The time gradient (differential value) of the output signal X is calculated. The extraction unit 24 outputs this time gradient as a signal Y indicating the speed of proximity of the motorcycle B to the user P.

  Here, when it is assumed that the user P and the moving body M (the car C or the motorcycle B) are traveling in a semi-free space where there are no obstacles, a spherical wave of the sound generated in the moving body M (the moving body M). The volume when a spherical wave having a point sound source is transmitted to the user P is inversely proportional to the square of the distance between the moving body M and the user P. Therefore, the time gradient (differential value) that is the amplitude of the sound signal Y increases as the speed of the moving body M that is close to the user P from the rear of the user P increases.

  The reproduction control unit 25 determines whether or not the time gradient of the volume, which is the amplitude of the output signal Y from the extraction unit 24, is equal to or greater than the threshold value TH2. When it is determined that the time gradient is equal to or greater than the threshold value TH2, the level LEV of the sound signal Z supplied from the reproducing unit 22 to the sound emitting unit 17 of the earphone 10 is decreased by a gradient according to the amplitude of the signal Y at the time of the determination. When the time length T has elapsed since this determination, the level LEV of the sound signal Z is returned to the original level. The process of reducing the level LEV of the sound signal Z with a gradient corresponding to the amplitude of the signal Y is performed, for example, by the following two modes.

  As shown in FIG. 4A, in the first mode, the playback control unit 25 determines the time length T1 (T1 <T from the time t when the amplitude of the output signal Y of the extraction unit 24 is determined to be equal to or greater than the threshold value TH2. ), The level LEV of the sound signal Z is decreased by ΔLEV (for example, ΔLEV = 10 dB), and the decreased level LEV−ΔLEV is maintained for a time length T2 (T2 = T−T1). To do. In this aspect, the time length T1 is shortened as the amplitude of the signal Y at time t increases. According to this aspect, as the moving body M behind the user P approaches the user P, the time required for lowering the sound volume in the ear of the user P becomes shorter. Therefore, according to this aspect, the user P running forward is audibly auditory without visually recognizing how dangerous the moving body M approaching from behind is approaching. I can know.

  As shown in FIG. 4B, in the second mode, the reproduction control unit 25 until the time length T1 elapses from the time t when it is determined that the amplitude of the output signal Y of the extraction unit 24 is equal to or greater than the threshold value TH2. During this period, the level LEV of the sound signal Z is lowered by ΔLEV, and the lowered level LEV−ΔLEV is maintained over the time length T2 (T2 = T−T1). In this aspect, the level LEV decrease amount ΔLEV is increased as the amplitude of the signal Y at time t increases. According to this aspect, the greater the speed at which the moving body M behind the user P approaches the user P, the greater the reduction in the volume of the sound in the user P's ear. Therefore, even in this mode, the user P running forward is audible without visually recognizing how dangerous the moving body M approaching from the rear is approaching. Can know.

  In the present embodiment described above, the moving body M (the car C or the motorcycle B) approaches from the rear while the user P is jogging while inserting the insertion portion 16 into the ear and listening to music. If so, the sound that is emitted by the moving body M is picked up by the sound pickup units 13 and 14. Then, the time gradient of the volume of the sound outside the ear when the insertion unit 16 is inserted into the ear is analyzed, and when the time gradient becomes equal to or greater than the threshold value TH2, the level LEV of the input signal Z of the sound emitting unit 17 is reduced. . Therefore, in this embodiment, when the moving body M behind the user P comes close to the moving body P at a certain speed, the volume of the sound emitted into the user's P ear is reduced. Therefore, according to the present embodiment, it is possible to inform the user P that the moving body M is approaching from behind and to take a risk avoiding action such as approaching the end of the road.

  Further, in the present embodiment, the time gradient of the volume is set as the analysis target, not the volume of the sound outside the ear when the insertion unit 16 is inserted into the ear. Therefore, it is possible to appropriately notify the user P how much the moving body M behind the vehicle P is approaching at a dangerous speed.

  In the present embodiment, the two sound collecting units 13 and 14 and the subtracting unit 23 arranged with a distance D therebetween constitute sound collecting means having a directivity axis in front of and behind the user. Therefore, it is possible to avoid the occurrence of a situation in which the volume of the sound that is erroneously reacted to the sound coming from a direction other than the rear and is emitted into the user P's ear is reduced.

  In the present embodiment, a waveform portion having the same characteristics as the emission sound of the car C or the motorcycle B in the waveform indicated by the output signal Y of the subtracting unit 23 is an analysis target. Therefore, it is possible to avoid the occurrence of a situation in which the volume of the sound that is erroneously reacted to the sound of an object other than the automobile C and the motorcycle B and is emitted to the user P's ear is reduced.

Although one embodiment of the present invention has been described above, the present invention may have other embodiments. For example, it is as follows.
(1) In the above embodiment, when the amplitude of the output signal Y of the extraction unit 24 is larger than the threshold value TH2, the reproduction control unit 25 has the entire band of the sound signal Z supplied from the reproduction unit 22 to the sound emission unit 17. Reduced the level. However, the frequency band in which the volume level of the sound signal Z is reduced may be controlled according to the waveform characteristics indicated by the output signal X of the subtracting unit 23. This embodiment is realized as follows, for example. When the waveform characteristic indicated by the output signal X of the subtractor 23 is the same as the characteristic of the waveform of the emission sound of the automobile C, the reproduction control unit 25 belongs to the band W _C (the emission sound of the automobile C belongs to the sound signal Z. Only the level of the band component is reduced. Further, when the characteristics of the waveform indicated by the output signal X of the subtracting unit 23 are the same as the characteristics of the waveform of the emission sound of the motorcycle B, the component of the band W _B (the band to which the emission sound of the motorcycle B belongs) in the sound signal Z. Reduce only the level. According to this embodiment, if it has the car C approaches from the rear of the user P, only the component of the band W _C the emission sound of the car C belongs among the sound is emitted in the ear of the user P Therefore, the user P can easily hear the sound emitted from the automobile C. Also, if you are approaching the motorcycle B from the rear of the user P, since only the components of the band W _B to release sound belongs bike B of the sound is emitted in the ear of the user P is reduced The user P can easily hear the sound emitted from the motorcycle B. Therefore, according to this embodiment, the user P can be alerted to the car C and the motorcycle B behind while listening to music.

(2) In the above-described embodiment, the two sound collecting units 13 and 14 and the subtracting unit 23 constitute a bi-directional sound collecting unit having directional axes in front and rear of the user P in a normal wearing state. It was. However, the sound collection units 13 and 14 and the subtraction unit 23 may be replaced with a directional microphone having a directional axis behind the user P in a normal wearing state.

(3) In the above embodiment, the present invention is applied as technical means for avoiding an accident when the user P wears the earphone 10 and performs jogging. However, the present invention may be applied as technical means for avoiding an accident when the user P wears the earphone 10 and rides a bicycle. Here, the range in which the user P can move per unit time differs depending on whether the user P jogs or rides a bicycle. Thus, when riding a bicycle, even if the time for notifying the proximity of the moving object M is delayed later than in jogging due to a decrease in sound volume, the user P can perform a behavior to avoid danger with a certain margin. is there. Therefore, when rowing a car, the threshold TH1 in the BPF process of the extraction unit 24 may be higher than that when jogging.

(4) In the above embodiment, when the user P is running on one lane side of a two-lane road, the moving body M ′ (that is, the user P running on the lane on the opposite side of the user P). The amount of decrease ΔLEV of the reproduction level when the time gradient of the volume of the sound emitted from the moving body M ′) approaching from the front exceeds the threshold value TH2 is set to the moving body M traveling on the same lane as the user P (that is, You may make it smaller than the fall amount (DELTA) LEV of the reproduction level when the time change of the sound volume of the emitted sound of the moving body M) approaching from the back of the user P exceeds the threshold value TH2. Further, the amount of decrease ΔLEV of the reproduction level LEV when the time gradient of the volume of the sound emitted from the moving body M traveling diagonally behind the user P exceeds the threshold value TH2 is expressed as the amount of sound emitted from the moving body M traveling directly behind. It may be smaller than the amount of decrease ΔLEV of the reproduction level LEV when the time gradient of the volume exceeds the threshold value TH2. That is, the reproduction level ΔLEV that is lowered according to the angle (horizontal azimuth angle) in the direction in which the moving body approaches the user P may be set.

(5) In the above embodiment, the volume of the sound emitted in the ear of the user P even when the moving body M other than the automobile C or the motorcycle B is approaching the user P from the back of the user P is set. It may be lowered. In this case, the volume decrease amount ΔLEV when the moving body M other than the car C or the motorcycle B is approaching the user P is the volume decrease amount ΔLEV when the car C or the motorbike B is approaching the user P. It may be smaller than ΔLEV.

(6) In the above embodiment, the extraction unit 24 moves behind the user P when the component of the band W _C (the band to which the emission sound of the car C belongs) in the output signal X of the subtraction unit 23 exceeds the threshold value TH1. If there is a motorcycle B running behind the user P when the component of the band W _B (band to which the emission sound of the motorcycle B belongs) in the signal X exceeds the threshold value TH1, assuming that the vehicle C is running. I saw it. However, the output signal X of the subtracting unit 23 is subjected to FFT (Fast Fourier Transform) processing, and it is determined from the power spectrum obtained as a result of the processing which of the user C's car C and motorcycle B is approaching. Good.

(7) In the above embodiment, the portable music player 20 may be stored in the pocket of the clothes of the user P without being raised from the neck of the user P.
(8) In the above embodiment, the present invention is realized by a portable music player. However, this may be realized by a mobile phone. In this case, it is preferable to install a program that realizes the storage unit 21, the reproduction unit 22, the subtraction unit 23, the extraction unit 24, and the reproduction control unit 25 in the CPU of the mobile phone.

(9) In the above embodiment, the processing procedure for reducing the level LEV of the sound signal Z with a gradient according to the amplitude of the signal Y is the first mode (FIG. 4A) or the second mode (FIG. 4). (B)) is not limited. A process for lowering the level LEV may be performed in another aspect different from these two aspects, or the process may be performed using both the first aspect and the second aspect.

DESCRIPTION OF SYMBOLS 1 ... Sound reproduction apparatus, 10 ... Earphone, 11 ... Main-body part, 12, 15 ... End surface, 13, 14 ... Sound collection part, 16 ... Insertion part, 17 ... Sound emission part, 20 ... Portable music player, 21 ... Memory | storage part , 22 ... reproducing unit, 23 ... subtracting unit, 24 ... extracting unit, 25 ... reproducing control unit.

Claims (5)

A sound emission part that emits a sound signal as a sound in the ear;
A sound collection unit that collects sound outside the ear;
A playback unit that supplies the sound signal to the sound output unit as a sound signal of a specified level;
And a reproduction control unit that controls a reproduction level of a sound signal supplied to the sound emitting unit when a time gradient of a volume of the sound collected by the sound collecting unit exceeds a threshold value. Playback device.   The reproduction control unit reduces the level of a sound signal supplied to the sound emitting unit for a predetermined time when the time gradient of the volume of the sound collected by the sound collecting unit is equal to or greater than a threshold value. The sound reproducing device according to claim 1.   An extraction unit for extracting a sound signal having an acoustic characteristic corresponding to a predetermined sound from the output signal of the sound collection unit, and the reproduction control unit obtains a time gradient of the sound signal extracted by the extraction unit; The sound reproducing apparatus according to claim 1, wherein the sound reproducing apparatus performs comparison with the threshold value.   2. The reproduction control unit controls a frequency band for reducing a level in a sound signal supplied to the sound emitting unit according to a waveform characteristic indicated by an output signal of the sound emitting unit. The sound reproducing device according to claim 1. 5. The sound reproduction device according to claim 1, wherein the sound collection unit is a sound collection unit having a sound collection directing axis behind the user. 6.

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