Audio device

Abstract

To provide an acoustic device which is used by being mounted on an ear of a listener and performs noise cancellation.SOLUTION: An acoustic device includes: a sound shielding section engaged with an external auditory canal so as to shield peripheral sound; a sound emission section arranged closer to an eardrum than the sound shielding section so as to output an acoustic signal; a sound collection section arranged in the neighborhood of a sound shielding position to shield the peripheral sound by the sound shielding section so as to collect the peripheral sound; a processing section for processing the acoustic signal in response to the peripheral sound collected by the sound collection section; and a housing for storing the sound emission section, the sound collection section, and the processing section. The sound shielding section is constituted by an earpiece for supporting the housing in the neighborhood of an entrance of the external auditory canal.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to an acoustic device mainly worn on the ears by a listener.

Background Art

[0002] A small acoustic conversion device, namely an earphone, that converts an electrical signal output from a playback device or a receiver into an acoustic signal with a speaker close to the ear or eardrum is widely popular. This type of acoustic playback device emits sound so that only the wearer can hear it, and thus is used in various environments.

[0003] For example, a canal-type earphone has a shape in which an earpiece is deeply inserted into the ear hole (ear canal). In this type of earphone, the sound-emitting element is generally arranged on the side opposite to the eardrum when viewed from the ear canal engaging portion of the earpiece (see, for example, Patent Document 1).

[0004] In addition, in earphones and headphones, a noise cancellation system that provides a good playback sound field space with reduced or eliminated external environmental noise is known. For example, in an active noise reduction system that performs active noise reduction, a microphone picks up external noise, and a noise cancellation signal that is acoustically out of phase with the noise is generated from the audio signal of the picked-up noise. By synthesizing this noise cancellation signal with an audio signal for the original listening purpose such as music and acoustically playing it back with a speaker, the external noise is acoustically canceled out.

[0005] Noise cancellation includes a feedforward method and a feedback method. In the feedforward method, the sound (noise) picked up at a position close to the ear is analyzed, and the noise waveform at the eardrum position of the listener is predicted to generate a signal (opposite-phase waveform) that cancels out the noise. In the feedback method, noise cancellation processing is performed on the sound (noise) picked up inside the housing by a microphone provided inside the housing of the acoustic device (see Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The object of the technology disclosed in this specification is to provide an acoustic device that is worn on the listener's ear and performs noise cancellation.

Means for Solving the Problems

[0008] The technology disclosed in this specification is a sound collection unit disposed near the entrance of the external auditory canal for collecting ambient sound, a sound emission unit disposed closer to the eardrum side than the sound collection unit for outputting an acoustic signal, and an acoustic device including the same.

[0009] The acoustic device further includes a sound insulation unit that engages with the external auditory canal to insulate ambient sound. The sound emission unit is disposed closer to the eardrum side than the sound insulation unit, and the sound collection unit is disposed near a sound insulation position where the ambient sound is insulated by the sound insulation unit. Further, the acoustic device further includes a processing unit that performs feed - forward type noise cancellation based on the ambient sound collected by the sound collection unit.

[0010] The acoustic device further has a housing that houses the sound emission unit, the sound collection unit, and the processing unit. The sound insulation unit is an earpiece that supports the housing near the entrance of the external auditory canal, and supports the housing so that the sound emission unit faces the eardrum side.

Effects of the Invention

[0011] According to the technology disclosed in this specification, it is possible to provide an acoustic device that is worn near the entrance of the listener's external auditory canal and performs noise cancellation by a feedforward method.

[0012] Note that the effects described in this specification are merely examples, and the effects of the present invention are not limited thereto. Further, the present invention may have additional effects other than the above effects.

[0013] Still other objects, features, and advantages of the technology disclosed in this specification will become apparent from more detailed descriptions based on the embodiments described below and the accompanying drawings.

Brief Description of the Drawings

[0014]

Figure 1

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Figure 19

[0015] Hereinafter, embodiments of the technology disclosed in this specification will be described in detail with reference to the drawings.

[0016] In this specification, a small-sized acoustic device having a feed-forward type noise canceling function and configured to be worn on the listener's ear, such as a canal type, is proposed below.

[0017] An acoustic device having a noise canceling function includes a sound emitting unit that reproduces a desired acoustic signal, a sound collection unit that collects ambient sound including noise in the external environment, and a processing unit that processes the acoustic signal output from the sound emitting unit according to the ambient sound collected by the sound collection unit.

[0018] The sound emitting unit is configured by combining any two or more of sound emitting elements such as dynamic speakers, balanced armature speakers, piezo elements, or electrostatic speakers, or a plurality of these sound emitting elements.

[0019] The desired acoustic signal is a reproduction signal such as music, and is supplied to the acoustic device from an external device such as a portable audio playback device or a multifunctional information terminal such as a smartphone or a tablet.

[0020] The sound collection unit is composed of a small microphone, and collects ambient sound including noise in the external environment that is generated while the sound emitting unit outputs an acoustic signal. In this embodiment, the sound collection unit is a microphone used for feedforward type noise cancellation.

[0021] The processing unit generates a cancellation signal such that the ambient sound is minimized based on the ambient sound collected by the sound collection unit. Specifically, the waveform of the signal of the ambient sound collected by the sound collection unit is analyzed to generate a signal of opposite phase that cancels the ambient sound, and this signal of opposite phase is superimposed on the ambient sound to cancel the ambient sound. Thereby, the ambient sound at the eardrum position is reduced. In the case of the feedforward method, the processing unit estimates what waveform the ambient sound will have when it reaches the eardrum, and generates a cancellation signal such that the ambient sound is minimized based on the estimation result.

[0022] FIG. 1 shows a basic configuration example of a noise canceling system 100. Hereinafter, each part will be described. The illustrated noise canceling system 100 includes a driver unit 110 as a sound emitting unit, a microphone 120 as a sound collection unit, and a signal processing unit 130 as a processing unit.

[0023] The signal processing unit 130 includes a DSP (Digital Signal Processor) 131 and a system controller 132. Under the control of the system controller 132, the DSP 131 executes processing of acoustic signals.

[0024] When the reproduction signal of the music source is taken into the noise cancellation system 100 via an audio input terminal (not shown), it is digitally converted by an AD converter (ADC) 133 and then input to the DSP 131. The music source mentioned here is an external device such as a portable audio playback device or a multifunctional information terminal such as a smartphone or a tablet. However, when the acoustic source transmits the reproduction signal wirelessly such as via Bluetooth (registered trademark) or Wi-Fi, a wireless interface may be equipped instead of the audio input terminal and the AD converter 133.

[0025] Also, the ambient sound signal composed of noise (such as noise) in the external environment picked up by the microphone 120 is amplified by the microphone amplifier 121, further digitally converted by an AD converter (ADC) 134, and then input to the DSP 131.

[0026] Inside the DSP 131, the equalizer 135 adjusts the frequency characteristics of the reproduction signal from the music source. Also, the noise cancellation engine unit 136 analyzes the waveform of the ambient sound signal captured from the microphone 120 and generates a cancellation signal of opposite phase to cancel the ambient sound. In this embodiment, since noise cancellation by the feedforward method is implemented, the noise cancellation engine unit 136 predicts the waveform of the ambient sound at the position of the listener's eardrum and generates a cancellation signal to cancel the ambient sound. Note that the noise cancellation engine unit 136 can be implemented by software processing. Then, the synthesizing unit 137 adds the cancellation signal to the reproduction signal after waveform shaping to generate a synthesized signal.

[0027] The composite signal output from the DSP 131 is converted into an analog signal by a digital-to-analog converter (DAC), further amplified by the earphone amplifier 111, and then acoustically output from the driver unit 110. The acoustic signal output from the driver unit 110 reaches the eardrum of the listener together with the ambient sound. Here, a cancellation signal with a phase opposite to that of the ambient sound is superimposed on the acoustic signal (as described above). Therefore, when this cancellation signal overlaps with the ambient sound, only the ambient sound is canceled out, enabling the listener to quietly enjoy music or the like.

[0028] The greater the correlation between the ambient sound signal observed by the microphone 120 and the ambient sound actually reaching the eardrum, the greater the noise cancellation effect. Therefore, by arranging the microphone 120 inside the ear canal or near the entrance of the ear canal, the correlation between the ambient sound observed by the microphone 120 and the ambient sound reaching the eardrum can be increased.

[0029] The acoustic device with a noise cancellation function proposed in this specification is assumed to be worn on the listener's ear, such as a canal type. This type of small acoustic device is generally used by inserting it near the entrance of the ear canal using an earpiece. In this case, since the ambient sound is shielded to some extent by the earpiece, the ambient sound leaking in from the earpiece occupies most of the ambient sound actually reaching the eardrum. Therefore, it can be said that arranging the microphone 120 near the sound shielding position that shields the ambient sound, in other words, near the earpiece, increases the correlation between the ambient sound signal observed by the microphone 120 and the ambient sound reaching the eardrum, and enhances the noise cancellation effect.

[0030] In addition, the acoustic device proposed in this specification is assumed to have a feedforward-type noise cancellation function. When implementing feedforward-type noise cancellation, the frequency band in which the noise cancellation effect can be obtained is determined by the relationship between the time t1 for sound waves to propagate between the driver unit 110 and the eardrum, the time t2 for ambient sound to propagate from the vicinity of the microphone 120 to the eardrum, and the processing time t3 of the ambient sound signal observed by the microphone 120. Note that the time t3 corresponds to the required time for analyzing the input signal of the microphone 120, generating a cancellation signal, and adding the cancellation signal to the reproduction signal by the synthesizing unit 137 and outputting it within the signal processing unit 130. The time shift Δt of the system input / output with respect to the ambient sound to be canceled in the noise cancellation system 100 is represented by the following formula (1).

[0031] [Number]

[0032] For example, when trying to ensure a noise cancellation amount of 20 dB or more at a certain frequency, it is considered necessary to suppress the above delay Δt within the range corresponding to 5 degrees of the phase of the signal to be canceled.

[0033] In the feedforward method, the microphone 120 is arranged outside the earphone (or headphone). However, if it is arranged further outside than the ear canal, the correlation between the ambient sound observed by the microphone 120 and the ambient sound reaching the eardrum becomes small, which is not preferable. When the position of the microphone 120 is fixed (near the sound insulation position), since the time t2 becomes constant, the shorter the time t1 for sound waves to propagate between the driver unit 110 and the eardrum, the wider the frequency band in which the noise cancellation effect can be obtained extends to the high frequency range.

[0034] In a general noise - canceling earphone, a sound - emitting element is arranged on the side opposite to the eardrum when viewed from the ear canal engaging portion of the earpiece (see, for example, Patent Document 1), has a sound - guiding portion extending from the sound - emitting element toward the eardrum side, and the earpiece is attached to the sound - guiding portion. In this case, the propagation time of sound waves is increased by the length of the earpiece. Also, a microphone for ambient sound detection is arranged more outside than the ear canal.

[0035] On the other hand, the acoustic device proposed in this specification includes an earpiece as a sound - insulating portion that engages with the ear canal to insulate ambient sound, a driver unit 110 as a sound - emitting portion arranged closer to the eardrum side than the earpiece and outputting a reproduction signal such as music, a microphone 120 as a sound - collecting portion arranged near the sound - insulating position where the earpiece insulates ambient sound and collecting ambient sound, a signal processing unit 130 that processes the reproduction signal according to the ambient sound observed by the microphone 120, and a housing that houses these driver unit 110, microphone 120, and signal processing unit 130.

[0036] In the acoustic device proposed in this specification, the driver unit 110 is arranged closer to the eardrum side than the engaging portion of the earpiece with the ear canal. Therefore, by shortening the distance between the driver unit 110 and the eardrum, the phase delay in the propagation path of the sound wave output from the driver unit 110 is reduced, so that the frequency band in which the noise - canceling effect can be obtained can be expanded up to the high - frequency range. It can also be said that by arranging the driver unit 110 closer to the eardrum than the sound - insulating position by the earpiece, the influence due to delay can be suppressed and the noise - canceling effect can be enhanced.

[0037] In addition, in the acoustic device proposed in this specification, the microphone 120 is disposed near a sound insulation position where ambient sound is insulated by the earpiece. The noise to be canceled is the ambient sound that leaks from the earpiece and reaches the eardrum. Therefore, by optimally disposing the microphone 120 near the sound insulation position, it becomes possible to observe with the microphone 120 the ambient sound that is actually to be canceled. That is, the correlation between the ambient sound signal observed by the microphone 120 and the ambient sound reaching the eardrum increases, and the noise canceling effect can be enhanced.

[0038] Incidentally, the ambient sound that leaks from the earpiece and reaches the eardrum, which is the target to be canceled, is actually an acoustic signal affected by reflections from the auricle, head, and body of the listener wearing the acoustic device. In the present embodiment, since the sound insulation position where the microphone 120 is disposed corresponds to the vicinity of the entrance of the external auditory canal, the microphone 120 can observe the ambient sound affected by reflections from the auricle, head, and body of the listener wearing the acoustic device. From this viewpoint as well, the noise canceling effect can be enhanced.

[0039] FIG. 2 shows the external configuration of the acoustic device 200 according to the present embodiment. The acoustic device 200 includes a housing 210 and an earpiece 250.

[0040] The housing 210 incorporates a driver unit 110, a microphone 120, a signal processing unit 130, and a battery as a driving power source for each of these units (none of which are shown in FIG. 2). Further, although an earphone cable for taking in a reproduction signal from an external device (music source) such as a portable audio reproduction device or a multifunctional information terminal such as a smartphone or a tablet may be connected to the housing 210, the illustration thereof is omitted in FIG. 2 for simplification.

[0041] FIG. 3 shows the external appearance configuration of the housing 210 alone. The housing 210 has a hollow cylindrical shape and incorporates a driver unit 110, a microphone 120, a signal processing unit 130, and a battery as a driving power source for each of these units inside. The housing 210 is made of elastic or plastic silicon rubber, elastomer, plastic such as ABS (Acrylonitrile Butadiene Styrene), or metal.

[0042] In FIG. 3, the arrangement examples of the driver unit 110 and the microphone 120 as acoustic elements are shown by broken lines respectively. The position of the driver unit 110 is on the eardrum side rather than the engagement portion with the external auditory canal of the earpiece 250. Also, the position of the microphone 120 is near the sound insulation position where the ambient sound is insulated by the earpiece 250. On the wall surface near the position where the microphone 120 of the housing 210 is arranged, one or more sound holes 211 for the microphone 120 to capture the ambient sound are formed.

[0043] FIG. 4 shows the cross-sectional configuration of the earpiece 250. The earpiece 250 is composed of an umbrella portion 251 that engages with the inner wall of the external auditory canal and a cylindrical portion 252 that holds the housing 210. The earpiece 250 is made of elastic or plastic silicon rubber, elastomer, etc.

[0044] FIG. 5 shows a state where the housing 210 is attached to the cross-section of the earpiece 250. Both the housing 210 and the earpiece 250 are substantially rotationally shaped, and the housing 210 is supported by the cylindrical portion 252 so that the central axis of the housing 210 substantially coincides with the central axis of the earpiece 250. The earpiece 250 may have an elliptical shape or a shape along the external auditory canal shape. Also, when the acoustic device 200 is worn on the listener's ear in a state where the housing 210 is attached to the earpiece 250, the position of the driver unit 110 is on the eardrum side rather than the engagement portion with the external auditory canal of the earpiece 250, and the position of the microphone 120 is near the sound insulation position where the ambient sound is insulated by the earpiece 250.

[0045] FIG. 6 shows a state in which the acoustic device 200 shown in FIGS. 2 to 5 is worn on the listener's ear. The ear canal is about 2.5 to 3 centimeters from the entrance to the eardrum and is curved in an S shape to prevent foreign objects from entering. The bend closer to the entrance is called the first curve, and the bend deeper inside is called the second curve. Therefore, unless the acoustic device 200 has a shape along the ear canal (first curve), it cannot be inserted deep inside. If it cannot be inserted deep inside, the distance between the driver unit 110 and the eardrum becomes longer, and the propagation time t1 of the sound wave becomes longer accordingly, so the noise canceling effect decreases.

[0046] If the acoustic device 200 is configured such that the central axis of the housing 210 can be inclined at an arbitrary angle with respect to the central axis of the earpiece 250 (at least within a certain angle range), the acoustic device 200 can be inserted deeper into the ear canal (in other words, closer to the eardrum).

[0047] FIG. 7 shows another example in which the acoustic device 200 is worn on the listener's ear. Here, the central axis 701 of the housing 210 with respect to the earpiece 250 is configured to be variable. By inclining the central axis 701 of the housing 210 with respect to the central axis 702 of the earpiece 250 along the shape of the ear canal (first curve), the acoustic device 200 can be inserted deeper into the ear canal than in the example shown in FIG. 6.

[0048] As shown in FIG. 4, the earpiece 250 includes an umbrella portion 251 that abuts against the inner wall of the ear canal and a cylindrical portion 252. And by inserting the housing 210 into the hollow cylindrical portion 252, the housing 210 is supported by the earpiece 250. Therefore, the earpiece 250 may be configured to support the housing 210 such that the inclination angle of the central axis of the housing 210 with respect to the central axis of the umbrella portion 251 is variable.

[0049] By configuring the earpiece 250 using elastic or plastic silicon rubber, elastomer, etc., the earpiece 250 can support the housing 210 so that the inclination angle is variable. Further, by configuring the housing 210 using elastic or plastic silicon rubber, elastomer, etc., the tip of the housing 210 can also come into contact with the inner wall of the outer ear canal and conform to the shape of the outer ear canal (the first curve).

[0050] However, since a reaction force acts according to the magnitude of the angle by which the central axis of the housing 210 is inclined with respect to the central axis of the umbrella portion 251, this reaction force is applied to the wall surface of the outer ear canal via the umbrella portion 251, which becomes a physical burden on the listener wearing the acoustic device 200.

[0051] Therefore, the earpiece 250 may be configured to reduce the reaction force that acts when the central axis of the housing 210 is inclined with respect to the central axis of the umbrella portion 251.

[0052] FIG. 8 illustrates a cross-section of the earpiece 250 configured to reduce the reaction force when the housing 210 is inclined. In the illustrated example, as shown by reference numerals 801 and 802, a wave surface shape centered on the central axis is formed on the front end surface of the earpiece 250. For this reason, the strength of the front end surface of the earpiece 250 decreases and it becomes easy to bend in the radial direction. As a result, the cylindrical portion 251 becomes easy to bend with respect to the front end surface, and the reaction force when the housing 210 is inclined decreases.

[0053] FIG. 9 shows a state in which the housing 210 is attached to the cross-section of the earpiece 250 shown in FIG. 8. Since the wave surface shape portions 801 and 802 of the front end surface of the earpiece 250 are easily deformed, even if the central axis 701 of the housing 210 is inclined with respect to the central axis 702 of the earpiece 250 as shown in the figure, the reaction force to return the central axis 701 of the housing 210 to the central axis 702 of the earpiece 250 is reduced.

[0054] Figure 10 also shows another example of the cross-section of the earpiece 250 configured to reduce the reaction force when the housing 210 is tilted. In the illustrated example, the cross-section of the earpiece 250 is configured in an H shape, and a cylindrical portion 252 is formed on a web (web plate) 1003 sandwiched between flanges 1001 and 1002 at both ends of the H shape, and is configured to support the earpiece 210. Comparing FIG. 10 with FIG. 4, the fulcrum when the tip of the housing 210 abuts against the wall surface of the external auditory canal and a moment is generated is set back from the tip surface of the in-piece 250 to approximately the central web 1003. Therefore, when an external force is applied to the tip of the earpiece 250 from the wall surface of the external auditory canal, the configuration example shown in FIG. 10 becomes larger and the tilt angle also becomes larger. In other words, when the central axis of the housing 210 is tilted by the same angle with respect to the central axis of the umbrella portion 251, the reaction force acting can be reduced more in the configuration example shown in FIG. 10 than in FIG. 4.

[0055] FIG. 11 shows a state in which the housing 210 is attached to the cross-section of the earpiece 250 shown in FIG. 10. Different from FIG. 8, the cross-section of the earpiece 250 is in an H shape, the tip surface of the earpiece 250 becomes an opening, and the web 1003 that supports the cylindrical portion 252 is more easily deformed with respect to the flanges 1001 and 1002. Further, the reaction force that tries to return the central axis 701 of the housing 210 to the central axis 702 of the earpiece 250 is reduced by the amount that the fulcrum is set back when the central axis 701 of the housing 210 is tilted with respect to the central axis 702 of the earpiece 250 as shown in the figure. Further, by reducing the plate thickness of the web 1003, the reaction force can be further reduced.

[0056] On the other hand, when the housing 210 is configured to reduce the reaction force when tilted with respect to the earpiece 250, the housing 210 may be easily tilted at any angle with respect to the earpiece 250, and there is a concern that the housing 210 may bend in an unnecessary direction and it may take time to attach it to the listener's ear. For this reason, the earpiece 250 may be configured so that the housing 210 is difficult to tilt in an undesired direction or tilts only in a desired direction.

[0057] FIG. 12 shows a top view of the earpiece 250 configured such that the housing 210 is less likely to tilt in an undesired direction. In the illustrated earpiece 250, a pair of ribs 1201 and 1202 are formed between the umbrella portion 251 and the cylindrical portion 252. Therefore, the cylindrical portion 252 (or the housing 210 supported by the cylindrical portion 252 (not shown in FIG. 12)) remains likely to tilt in the A direction, but is less likely to tilt in the B direction.

[0058] Further, FIG. 13 shows a top view of the earpiece 250 configured such that the housing 210 tilts only in a desired direction. In the illustrated earpiece 250, an elastic body such as a sponge 1301 is packed between the umbrella portion 251 and the cylindrical portion 252. Therefore, the cylindrical portion 252 (or the housing 210 supported by the cylindrical portion 252 (not shown in FIG. 13)) is likely to tilt in the C direction which is the gap of the sponge 1301, but a high load is applied when tilting in other directions.

[0059] Subsequently, the internal configuration of the housing 210 will be described in detail.

[0060] As shown in FIG. 3, the housing 210 has a hollow cylindrical shape, and a driver unit 110 and a microphone 120 are accommodated therein. Although not shown in FIG. 3, a signal processing unit 130 that performs processing such as noise cancellation and a battery as a driving power source are also arranged in the housing 210.

[0061] The position of the driver unit 110 is closer to the eardrum side than the engagement portion with the external auditory canal of the earpiece 250. By shortening the distance between the driver unit 110 and the eardrum, the phase delay in the propagation path of the sound wave output from the driver unit 110 is reduced, so the frequency band in which the noise cancellation effect can be obtained can be expanded up to the high frequency range. It can also be said that by arranging the driver unit 110 closer to the eardrum than the sound insulation position by the earpiece 250, the influence due to the delay can be suppressed and the noise cancellation effect can be enhanced.

[0062] Also, the position of the microphone 120 is near the sound insulation position where the ambient sound is blocked by the earpiece 250. On the wall surface near the position where the microphone 120 is arranged in the housing 210, one or more sound holes 211 for the microphone 120 to capture the ambient sound are drilled. The noise to be canceled is the ambient sound that leaks into the ear canal through the gap of the earpiece 250 and reaches the eardrum. Therefore, by the microphone 120 collecting the ambient sound near the sound insulation position of the earpiece 250, it becomes possible to observe with the microphone 120 the ambient sound that is actually to be canceled. That is, the correlation between the ambient sound signal observed by the microphone 120 and the ambient sound reaching the eardrum becomes large, and the noise canceling effect can be enhanced.

[0063] The ambient sound that leaks from the earpiece and reaches the eardrum and is to be canceled is actually an acoustic signal affected by the reflection from the auricle, head, and body of the listener wearing the acoustic device. As can be seen from FIG. 6 or FIG. 7, since the sound hole 211 of the microphone 120 is arranged near the entrance of the ear canal, the microphone 120 can observe the ambient sound affected by the reflection from the auricle, head, and body of the listener wearing the acoustic device. From this perspective as well, the noise canceling effect can be enhanced.

[0064] FIG. 14 shows a modified example of the acoustic device 200. In the configuration example of the acoustic device 200 shown in FIG. 5, the rear end of the housing 210 protrudes from the cylindrical portion 252 of the earpiece 250. In contrast, in the configuration example of the acoustic device 200 shown in FIG. 14, the housing portion 210 is inserted into the cylindrical portion 252 up to the rear end, and accordingly, the drive unit 110 on the front end side can be brought closer to the eardrum, and the noise canceling effect is enhanced. Also, the position where the microphone 120 is arranged is covered by the cylindrical portion 252. Therefore, as shown in FIG. 15, a sound hole 1501 for the microphone 120 is also drilled in the wall surface of the cylindrical portion 252 corresponding to the sound hole 211.

[0065] In order to improve the volume efficiency, a small microphone may be installed. Fig. 16 shows a configuration example of the acoustic device 200 in which the miniaturized microphone 120 is arranged deep inside the earpiece 250.

[0066] In an acoustic output device such as a speaker, it is common practice to provide a space for adjusting the acoustic characteristics on the front or back surface of the diaphragm.

[0067] Similarly, in the acoustic device 200 according to the present embodiment, it is preferable to provide a space for adjusting the acoustic characteristics. Fig. 17 shows a state in which a front space 1701 and a back space 1702 are provided on the diaphragm side and the side opposite to the diaphragm of the driver unit 110, respectively, inside the housing 210.

[0068] When the acoustic device 200 is housed in the ear canal, it is assumed that it is difficult to provide a space for adjusting the acoustic characteristics on the front or back surface of the driver unit 110 in the housing 210. Therefore, a space for adjusting the acoustic characteristics may be provided at an arbitrary location inside the housing 210, and the space may be connected to the tip of the housing 210 on the diaphragm side by an acoustic conduction portion.

[0069] Fig. 18 shows another configuration example of the acoustic device 200 in which a space for adjusting the acoustic characteristics is provided inside the housing 210. In the figure, a front space 1801 is provided on the side opposite to the diaphragm of the driver unit 110 inside the housing 210, and the front space 1801 is connected to the tip of the housing 210 on the diaphragm side by a tube-shaped acoustic conduction portion 1802 to secure a space for adjusting the acoustic characteristics.

[0070] FIG. 19 shows still another configuration example of the acoustic device 200 in which a space for adjusting acoustic characteristics is provided inside the housing 210. In this figure, inside the housing 210, both a front space 1901 and a rear space 1902 are provided on the side opposite to the diaphragm of the driver unit 110 to secure a space for adjusting acoustic characteristics. Further, the portion from the front space 1901 to the tip on the diaphragm side of the housing 210 is connected by a tubular sound guide portion 1903.

[0071] So far, the arrangement of the processing unit 130 and the battery inside the housing 210 has not been particularly mentioned. Different from acoustic elements such as the driver unit 110 and the microphone 120, the processing unit 130 and the battery are not subject to the constraints of the arrangement in terms of acoustic characteristics. Therefore, for example, the processing unit 130 and the battery may be combined and modularized for handling, and may be arranged separately together with the driver unit 110 and the microphone 120 inside the housing 210. Each module is electrically connected by a flexible wiring material, and the housing 210 is made of an elastic member such as silicon rubber or elastomer, so that the relative positions of the modules can change slightly according to the deformation of the housing 210, and an acoustic device 200 with a good wearing feeling can be realized.

[0072] Note that the processing unit 130 and the battery can use those on the external device side that serves as a music source. The music source is, for example, a portable audio playback device or a multifunctional information terminal such as a smartphone or a tablet. In such a case, a cord for electrically connecting to the driver unit 110 and the microphone 120 extends from the housing 210 and is connected to the external device.

[0073] Further, the acoustic device 200 can also be configured so that the processing unit 130 and the battery mounted inside the housing 210 and an external device connected by a wired connection (or a wireless connection) can be switched and used. For example, the housing 210 may be equipped with a connector that can be connected to each of the internal processing unit 130 and the battery and the external device, and a switching function for selectively connecting to either one.

[0074] Finally, the effects of the acoustic device proposed in this specification will be summarized.

[0075] According to the acoustic device proposed in this specification, by arranging the driver unit 110 on the eardrum side, the distance between the driver unit 110 and the eardrum is shortened, and the phase delay in the sound wave propagation path is reduced, so that the noise cancellation effect can be obtained up to the high frequency range.

[0076] Also, according to the acoustic device proposed in this specification, the microphone 120 is arranged near the sound insulation position where the ambient sound is sound-insulated by the earpiece, and the ambient sound to be actually canceled is observed by the microphone 120, so that the noise cancellation effect can be enhanced. Further, since the microphone 120 is arranged near the entrance of the external auditory canal, the ambient sound affected by the reflection from the auricle, head, and body of the listener wearing the acoustic device is observed, so that the noise cancellation effect is even higher.

Industrial Applicability

[0077] As described above, the technology disclosed in this specification has been described in detail with reference to specific embodiments. However, it is obvious that those skilled in the art can make modifications and substitutions to the embodiments without departing from the gist of the technology disclosed in this specification.

[0078] The technology disclosed in this specification is used by being worn on the ear of a listener and can be applied to various types of acoustic devices that perform noise cancellation.

[0079] In short, the technology disclosed in this specification has been described in the form of examples, and the content described in this specification should not be interpreted restrictively. To determine the gist of the technology disclosed in this specification, the claims should be referred to.

[0080] Note that the technology disclosed in this specification can also have the following configurations.

[0081] (1) An acoustic device comprising a sound collection unit disposed near the entrance of the external auditory canal for collecting ambient sound, and a sound generation unit disposed closer to the eardrum side than the sound collection unit for outputting an acoustic signal. An acoustic device comprising:

[0082] (1-1) An acoustic device comprising a sound insulation unit that engages with the external auditory canal to insulate ambient sound, and a sound generation unit disposed closer to the eardrum side than the sound insulation unit for outputting an acoustic signal, and a sound collection unit disposed near a sound insulation position where ambient sound is insulated by the sound insulation unit for collecting ambient sound. An acoustic device comprising:

[0083] (3) Further comprising a sound insulation unit that engages with the external auditory canal to insulate ambient sound, wherein the sound generation unit is disposed closer to the eardrum side than the sound insulation unit, and the sound collection unit is disposed near a sound insulation position where ambient sound is insulated by the sound insulation unit. The acoustic device according to (1) above.

[0084] (3) Further comprising a processing unit that processes the acoustic signal according to the ambient sound collected by the sound collection unit. The acoustic device according to (2) above.

[0085] (4) The processing unit performs noise cancellation based on the ambient sound collected by the sound collection unit. The acoustic device according to (3) above.

[0086] (4-1) The processing unit performs feedforward-type noise cancellation. The acoustic device according to (4) above.

[0087] (5) Further having a housing that houses the sound generation unit, the sound collection unit, and the processing unit. The acoustic device according to (3) above.

[0088] (6) The sound insulation unit is an earpiece that supports the housing near the entrance of the external auditory canal. The acoustic device according to the above (5).

[0089] (7) The earpiece supports the housing such that the sound - generating part faces the eardrum side. The acoustic device according to the above (6).

[0090] (8) The housing has a substantially cylindrical shape. The earpiece supports the housing such that the inclination angle of the central axis of the housing is variable. The acoustic device according to any one of the above (6) or (7).

[0091] (9) The earpiece includes an umbrella part that contacts the inner wall of the ear canal and a cylindrical part that holds the housing within the umbrella part, and supports the housing such that the inclination angle of the central axis of the housing with respect to the central axis of the umbrella part is variable. The acoustic device according to the above (8).

[0092] (10) The housing has sound holes for the sound - collecting part drilled near a sound - insulating position where ambient sound is sound - insulated by the earpiece. The acoustic device according to any one of the above (6) to (9).

[0093] (11) The earpiece includes an umbrella part that contacts the inner wall of the ear canal and a cylindrical part that holds the housing within the umbrella part. The sound holes are arranged inside the umbrella part. The acoustic device according to the above (10).

[0094] (12) The earpiece includes a cylindrical part that holds the housing within the umbrella part. The cylindrical part has an opening at a location corresponding to the sound holes. The acoustic device according to the above (11).

[0095] (13) The housing has at least one of a front space or a rear space for adjusting the acoustic characteristics of the sound output from the sound - generating part. The acoustic device according to any one of (5) to (12) above.

[0096] (14) The housing includes the front space and a sound guiding portion extending from the front space to the tip on the tympanic membrane side of the housing. The acoustic device according to (13) above.

[0097] (15) The housing includes the front space and the rear space at the rear. The acoustic device according to (13) above.

Explanation of Reference Numerals

[0098] 100…Noise cancellation system 110…Driver unit, 111…Earphone amplifier 120…Microphone, 121…Microphone amplifier 130…Signal processing unit 131…DSP (Digital Signal Processor) 132…System controller, 133…AD converter (ADC) 134…AD converter (ADC), 135…Equalizer 136…Noise cancellation engine unit, 137…Synthesis unit 138…DA converter (DAC) 200…Acoustic device, 210…Housing, 211…Sound hole 250…Earpiece, 251…Umbrella portion, 252…Tube portion

Claims

1. A sound collection unit that collects ambient sound, a sound emission unit that is disposed closer to the eardrum side than the sound collection unit and outputs an acoustic signal subjected to noise cancellation based on the ambient sound collected by the sound collection unit, a housing that houses the sound collection unit and the sound emission unit, an earpiece that engages near the entrance of the external auditory canal to block ambient sound and supports the housing near the entrance of the external auditory canal, comprising: the sound collection unit is disposed near a sound insulation position where the earpiece blocks ambient sound, an acoustic device.

2. the sound emission unit is disposed closer to the eardrum side than the earpiece, the acoustic device according to Claim 1.

3. the housing further houses a processing unit that performs noise cancellation on the acoustic signal based on the ambient sound collected by the sound collection unit, the acoustic device according to Claim 1.

4. the earpiece supports the housing such that the sound emission unit faces the eardrum side, the acoustic device according to Claim 1.

5. the housing has a substantially cylindrical shape, the earpiece supports the housing such that the inclination angle of the central axis of the housing is variable, the acoustic device according to Claim 1.

6. the earpiece includes an umbrella portion that contacts the inner wall of the external auditory canal and a cylindrical portion that holds the housing within the umbrella portion, and supports the housing such that the inclination angle of the central axis of the housing with respect to the central axis of the umbrella portion is variable, the acoustic device according to Claim 5.

7. sound holes for the sound collection unit are formed in the housing near a sound insulation position where the earpiece blocks ambient sound, the acoustic device according to Claim 1.

8. the earpiece includes an umbrella portion that contacts the inner wall of the external auditory canal and a cylindrical portion that holds the housing within the umbrella portion, the sound holes are disposed inside the umbrella portion, the acoustic device according to Claim 7.

9. the earpiece includes a cylindrical portion that holds the housing within the umbrella portion, the cylindrical portion has an opening at a location corresponding to the sound holes, the acoustic device according to Claim 8.

10. the housing has at least one of a front space or a rear space for adjusting the acoustic characteristics of the sound output from the sound emission unit, the acoustic device according to Claim 1.

11. the housing includes the front space and a sound guiding portion that extends from the front space to the tip of the housing on the eardrum side, the acoustic device according to Claim 10.

12. The housing includes the front space and the rear space at the rear. The acoustic device according to claim 10.

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