WO2024100816A1 - 音響信号出力装置 - Google Patents

音響信号出力装置 Download PDF

Info

Publication number
WO2024100816A1
WO2024100816A1 PCT/JP2022/041805 JP2022041805W WO2024100816A1 WO 2024100816 A1 WO2024100816 A1 WO 2024100816A1 JP 2022041805 W JP2022041805 W JP 2022041805W WO 2024100816 A1 WO2024100816 A1 WO 2024100816A1
Authority
WO
WIPO (PCT)
Prior art keywords
acoustic signal
driver unit
reflector
emitted
sound
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2022/041805
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
達也 加古
大将 千葉
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NTT Inc
Original Assignee
Nippon Telegraph and Telephone Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to JP2024556929A priority Critical patent/JPWO2024100816A1/ja
Priority to PCT/JP2022/041805 priority patent/WO2024100816A1/ja
Publication of WO2024100816A1 publication Critical patent/WO2024100816A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only 
    • H04R1/26—Spatial arrangements of separate transducers responsive to two or more frequency ranges
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means

Definitions

  • the present invention relates to an audio signal output device, and in particular to an audio signal output device that does not seal the ear canal.
  • open-ear earphones and headphones have the problem of significant sound leakage to the surroundings. This problem is not limited to open-ear earphones and headphones, but is a common problem with audio signal output devices that do not seal the ear canal, including installed speakers and built-in speakers.
  • the present invention was made in consideration of these points, and aims to provide an acoustic signal output device that does not seal the ear canal and can suppress sound leakage to the surroundings.
  • An acoustic signal output device has a concave reflector with a paraboloid of revolution or a surface approximating a paraboloid of revolution on the inside, and a first driver unit disposed inside the reflector.
  • the acoustic signal emitted from the first driver unit to one side is the first acoustic signal
  • the acoustic signal emitted from the first driver unit to the other side is the second acoustic signal.
  • This acoustic signal output device is designed so that when the first acoustic signal is emitted from one side of the first driver unit and the second acoustic signal is emitted from the other side of the first driver unit, the attenuation rate of the first acoustic signal at a second point farther from the acoustic signal output device than the first point based on a predetermined first point where the first acoustic signal arrives is equal to or less than a predetermined value that is smaller than the attenuation rate of the acoustic signal due to air propagation at the second point based on the first point.
  • this acoustic signal output device is designed so that in such a case, the attenuation amount of the first acoustic signal at the second point based on the first point is equal to or greater than a predetermined value that is larger than the attenuation amount of the acoustic signal due to air propagation at the second point based on the first point.
  • This structure helps prevent sound from leaking into the surrounding area.
  • FIG. 1 is a see-through front view illustrating the configuration of an acoustic signal output device according to a first embodiment.
  • FIG. 2 is a transparent plan view illustrating the configuration of the acoustic signal output device according to the first embodiment.
  • FIG. 3 is a cross-sectional view taken along line 1-1 of FIG.
  • FIG. 4 is a cross-sectional view taken along line 2-2 of FIG.
  • FIG. 5 is a conceptual diagram illustrating the arrangement of sound holes.
  • FIG. 6 is a conceptual diagram for explaining the relationship between the paraboloid of revolution and the focal point.
  • Fig. 7A is a conceptual diagram for explaining the direction of travel of an acoustic signal when a driver unit is placed at the focal point of a paraboloid of revolution.
  • Fig. 7A is a conceptual diagram for explaining the direction of travel of an acoustic signal when a driver unit is placed at the focal point of a paraboloid of revolution.
  • Fig. 7A is a conceptual diagram for
  • FIG. 7B is a conceptual diagram for explaining the direction of travel of an acoustic signal when a driver unit is not placed at the focal point of a paraboloid of revolution.
  • Fig. 8A is a conceptual diagram illustrating a configuration in which a horn is attached to a driver unit
  • Fig. 8B is a conceptual diagram illustrating an arrangement configuration of the acoustic signal output device of the first embodiment.
  • Fig. 9A is a block diagram illustrating a functional configuration for supplying a signal to a driver unit
  • Fig. 9B is a diagram illustrating a sound pressure level at an observation point.
  • 10A and 10B are graphs illustrating the directional characteristics of an acoustic signal output device.
  • FIG. 11A and 11B are graphs for illustrating the directional characteristics of an acoustic signal output device.
  • FIG. 12 is a graph illustrating the directional characteristics of the acoustic signal output device.
  • 13A and 13B are graphs illustrating the frequency characteristics of the acoustic signal output device.
  • 14A and 14B are graphs for illustrating the frequency characteristics of the acoustic signal output device.
  • FIG. 15 is a graph illustrating the frequency characteristics of the acoustic signal output device.
  • FIG. 16 is a front view illustrating a modified example of the arrangement of the sound holes.
  • FIG. 17 is a front view illustrating a modified example of the arrangement of the sound holes.
  • FIG. 16 is a front view illustrating a modified example of the arrangement of the sound holes.
  • FIG. 18 is a see-through front view illustrating the configuration of an acoustic signal output device according to a modified example of the first embodiment.
  • FIG. 19 is a transparent plan view illustrating the configuration of an acoustic signal output device according to a modified example of the first embodiment.
  • Fig. 20A is a transparent plan view illustrating the configuration of a housing of a modified example of the first embodiment
  • Fig. 20B is a transparent front view illustrating the configuration of the housing of a modified example of the first embodiment
  • Fig. 20C is a bottom view illustrating the configuration of the housing of the modified example of the first embodiment.
  • FIG. 21 is a cross-sectional view taken along line 19-19 of FIG.
  • FIG. 22A and 22B are cross-sectional views for illustrating the configuration of an acoustic signal output device according to a modified example of the first embodiment.
  • FIG. 23 is a see-through front view illustrating the configuration of an acoustic signal output device according to the second embodiment.
  • FIG. 23 is a transparent plan view illustrating the configuration of an acoustic signal output device according to the second embodiment.
  • FIG. 25 is a see-through front view illustrating the configuration of an acoustic signal output device according to a modified example of the second embodiment.
  • FIG. 26 is a see-through front view illustrating the configuration of an acoustic signal output device according to a modified example of the second embodiment.
  • FIG. 27A is a graph illustrating the frequency characteristics of an acoustic signal observed on the cutout side
  • Fig. 27B is a graph illustrating the frequency characteristics of an acoustic signal observed on the side where no cutout is provided
  • Fig. 28A is a graph illustrating the frequency characteristics of an acoustic signal observed on a side with a cutout and a side without a cutout
  • Fig. 28B is a graph illustrating the difference in frequency characteristics of an acoustic signal due to the difference in the cutout.
  • FIG. 29 is a see-through front view illustrating the configuration of an acoustic signal output device according to the third embodiment.
  • Fig. 30A is a block diagram illustrating a functional configuration for supplying a signal to a driver unit.
  • Fig. 30B is a diagram illustrating a sound pressure level at an observation point.
  • the acoustic signal output device 10 of this embodiment is a device for listening to sound (e.g., open-ear type earphones, headphones, installed speakers, embedded speakers, etc.) that is worn without sealing the user's ear canal. As illustrated in Figs.
  • the acoustic signal output device 10 of this embodiment has a concave (e.g., parabolic) reflector 13 having a paraboloid of revolution or a surface similar to a paraboloid of revolution on the inside, driver units 11 and 15 (speaker driver units, drivers) that convert an output signal (electrical signal representing an acoustic signal) output from a playback device into an acoustic signal and output it, a housing 16 that houses the driver unit 15 inside, and a support part 14 for placing the driver unit 11 inside the reflector 13.
  • a concave e.g., parabolic
  • driver units 11 and 15 that convert an output signal (electrical signal representing an acoustic signal) output from a playback device into an acoustic signal and output it
  • housing 16 that houses the driver unit 15 inside
  • a support part 14 for placing the driver unit 11 inside the reflector 13.
  • the frequency band of the reproduced acoustic signal (reproduced acoustic signal) is divided into a high frequency band and a low frequency band, and the driver unit 11 emits the high frequency band acoustic signal of the reproduced acoustic signal. That is, the driver unit 11 mainly handles high frequency acoustic signals of the reproduced acoustic signal.
  • the output signal output from the reproduction device is separated into a high frequency band signal on the high frequency side and a low frequency band signal on the lower frequency side, and the high frequency band signal separated in this manner is input to the driver unit 11.
  • the driver unit 11 is a device (device with a speaker function) that emits (emits sound) an acoustic signal AC1 (first acoustic signal) based on the input high frequency band signal to one side (D1 direction side), and emits an acoustic signal AC2 (second acoustic signal) that is an inverse phase signal (phase inversion signal) of the acoustic signal AC1 or an approximation signal of the inverse phase signal to the other side (D2 direction side).
  • a device device with a speaker function
  • an acoustic signal emitted from the driver unit 11 to one side is called an acoustic signal AC1 (first acoustic signal)
  • an acoustic signal emitted from the driver unit 11 to the other side is called an acoustic signal AC2 (second acoustic signal).
  • the driver unit 11 is disposed near an axis A1 (axis) extending along the D1 direction or the axis A1 (axis), and the acoustic signals AC1 and AC2 are emitted along the axis A1 (axis).
  • the driver unit 11 includes a diaphragm 113 that emits an acoustic signal AC1 in the D1 direction from one surface 113a by vibration, and emits an acoustic signal AC2 in the D2 direction from the other surface 113b by this vibration (FIG. 1).
  • the diaphragm 113 is disposed near the axis A1 (axis) or the axis A1 (axis).
  • the driver unit 11 emits the acoustic signal AC1 from the surface 111 on one side in the D1 direction by vibrating the diaphragm 113 based on the input high-frequency band signal, and emits the acoustic signal AC2, which is an inverse phase signal of the acoustic signal AC1 or an approximation of the inverse phase signal, from the surface 112 on the other side in the D2 direction. That is, the acoustic signal AC2 is emitted secondarily with the emission of the acoustic signal AC1.
  • the D2 direction (the other side) is, for example, the opposite direction to the D1 direction (one side), but the D2 direction does not need to be strictly the opposite direction to the D1 direction, as long as the D2 direction is different from the D1 direction.
  • the relationship between the one side (D1 direction) and the other side (D2 direction) depends on the type and shape of the driver unit 11.
  • the acoustic signal AC2 may be strictly an inverse phase signal of the acoustic signal AC1, or the acoustic signal AC2 may be an approximation of the inverse phase signal of the acoustic signal AC1.
  • the approximation signal of the opposite phase signal of the acoustic signal AC1 may be (1) a signal obtained by shifting the phase of the opposite phase signal of the acoustic signal AC1, (2) a signal obtained by changing (amplifying or attenuating) the amplitude of the opposite phase signal of the acoustic signal AC1, or (3) a signal obtained by shifting the phase of the opposite phase signal of the acoustic signal AC1 and further changing the amplitude.
  • the phase difference between the opposite phase signal of the acoustic signal AC1 and its approximation signal is desirably ⁇ 1% or less of one period of the opposite phase signal of the acoustic signal AC1.
  • Examples of ⁇ 1% are 1%, 3%, 5%, 10%, 20%, etc.
  • the difference between the amplitude of the opposite phase signal of the acoustic signal AC1 and the amplitude of its approximation signal is desirably ⁇ 2% or less of the amplitude of the opposite phase signal of the acoustic signal AC1.
  • Examples of ⁇ 2% are 1%, 3%, 5%, 10%, 20%, etc.
  • examples of the type of the driver unit 11 include a dynamic type, a balanced armature chair type, a hybrid type of a dynamic type and a balanced armature type, and a capacitor type.
  • the outer shape of the driver unit 11 is a substantially cylindrical shape with both end faces, and the diaphragm 113 is a substantially disc shape, but this does not limit the present invention.
  • the outer shape of the driver unit 11 may be a rectangular parallelepiped shape, and the diaphragm 113 may be a dome shape.
  • examples of the acoustic signal include music, voice, sound effects, environmental sounds, and other sounds.
  • the driver unit 15 of this embodiment is disposed on the D2 direction side of the driver unit 11.
  • the driver unit 15 is larger in size than the driver unit 11, and emits the low-frequency band acoustic signal among the above-mentioned reproduced acoustic signals. That is, the driver unit 15 mainly handles low-frequency acoustic signals among the reproduced acoustic signals. This makes it possible to obtain low-frequency sound pressure compared to the case where only the driver unit 11 is used.
  • the driver unit 15 is a device (device having a speaker function) that emits (emits sound) an acoustic signal AC3 (third acoustic signal) based on the input low-frequency band signal to one side (D1 direction side), and emits an acoustic signal AC4 (fourth acoustic signal) which is an inverse phase signal (phase inversion signal) of the acoustic signal AC3 or an approximation signal of the inverse phase signal to the other side (D2 direction side).
  • a device device having a speaker function
  • the acoustic signal emitted from the driver unit 15 to one side is called acoustic signal AC3 (third acoustic signal), and the acoustic signal emitted from the driver unit 15 to the other side (D2 direction side) is called acoustic signal AC4 (fourth acoustic signal).
  • the driver unit 15 is arranged on the axis A1 (axis) or in the vicinity of the axis A1 (axis), and the acoustic signals AC3 and AC4 are emitted along the axis A1 (axis).
  • the driver unit 15 includes a diaphragm 153 (second diaphragm) that emits an acoustic signal AC3 (third acoustic signal) from one surface 153a to the D1 direction side (one side) by vibration, and emits an acoustic signal AC4 (fourth acoustic signal) from the other surface 153b to the D2 direction side (other side) by this vibration (FIG. 12).
  • the diaphragm 153 is arranged on the axis A1 (axis) or in the vicinity of the axis A1 (axis).
  • the driver unit 15 emits the acoustic signal AC3 from one side surface 151 in the direction D1 by vibrating the diaphragm 153 based on the input low-frequency band signal, and emits the acoustic signal AC4, which is an in-phase signal or an approximation signal of the in-phase signal of the acoustic signal AC3, from the other side surface 152 in the direction D2. That is, the acoustic signal AC4 is emitted secondarily in association with the emission of the acoustic signal AC3.
  • the acoustic signal AC3 is an in-phase signal or an approximation signal of the in-phase signal of the acoustic signal AC1
  • the acoustic signal AC4 is an in-phase signal or an approximation signal of the in-phase signal of the acoustic signal AC2.
  • the acoustic signal AC4 may be strictly an in-phase signal of the acoustic signal AC3, or the acoustic signal AC4 may be an approximation signal of the in-phase signal of the acoustic signal AC3.
  • the approximation signal of the opposite phase signal of the acoustic signal AC3 may be (1) a signal obtained by shifting the phase of the opposite phase signal of the acoustic signal AC3, (2) a signal obtained by changing (amplifying or attenuating) the amplitude of the opposite phase signal of the acoustic signal AC3, or (3) a signal obtained by shifting the phase of the opposite phase signal of the acoustic signal AC3 and further changing the amplitude.
  • the phase difference between the opposite phase signal of the acoustic signal AC3 and its approximation signal is desirably ⁇ 3% or less of one period of the opposite phase signal of the acoustic signal AC3.
  • Examples of ⁇ 3% are 1%, 3%, 5%, 10%, 20%, etc.
  • the difference between the amplitude of the opposite phase signal of the acoustic signal AC3 and the amplitude of its approximation signal is desirably ⁇ 4% or less of the amplitude of the opposite phase signal of the acoustic signal AC3.
  • Examples of ⁇ 4% are 1%, 3%, 5%, 10%, 20%, etc.
  • examples of the type of the driver unit 15 include a dynamic type, a balanced armature chair type, a hybrid type of a dynamic type and a balanced armature type, and a condenser type.
  • the outer shape of the driver unit 15 is a substantially cylindrical shape with both end faces, and the diaphragm 153 is a substantially disc shape, but this does not limit the present invention.
  • the outer shape of the driver unit 15 may be a rectangular parallelepiped shape, and the diaphragm 153 may be a dome shape.
  • the driver unit 15 is larger in size than the driver unit 11.
  • the diameter of the driver unit 11 (diameter in the direction perpendicular to the D1 direction and/or the D2 direction) is S11 and the diameter of the driver unit 15 (diameter in the direction perpendicular to the D1 direction and/or the D2 direction) is S21, then S21>S11 is satisfied.
  • S21 is more than twice as large as S11, S11 is 12 mm, and S21 is 35 mm.
  • the diameter of the diaphragm 113 (diameter in the direction perpendicular to the D1 direction and/or the D2 direction) is S12 and the diameter of the diaphragm 153 (diameter in the direction perpendicular to the D1 direction and/or the D2 direction) is S22, then S22>S12 is satisfied.
  • S22 is more than twice as large as S12, S12 is 10 mm, and S22 is 30 mm. That is, the diameter of diaphragm 153 (second diaphragm) is larger than the diameter of diaphragm 113 (first diaphragm).
  • the reflector 13 is a concave structure having a paraboloid of revolution or a surface approximating a paraboloid of revolution on the inside. That is, at least a part of the inner wall surface 131 of the reflector 13 is a paraboloid of revolution or a surface approximating a paraboloid of revolution.
  • This paraboloid of revolution has a shape obtained by rotating a parabola around the axis A1 (a specific axis), for example.
  • the entire inner wall surface 131 may be a paraboloid of revolution or a surface approximating a paraboloid of revolution, or only a part of the inner wall surface 131 (for example, only the inner wall surface 131 on the bottom 131a side of the reflector 13 or only the inner wall surface 131 on the tip 131c side) may be a paraboloid of revolution or a surface approximating a paraboloid of revolution.
  • the driver unit 11 is disposed inside the reflector 13.
  • the driver unit 11 is fixed to an inner wall surface 131 of the reflector 13 via a support 14.
  • one surface 111 of the driver unit 11 disposed inside the reflector 13 faces the open end 130 side (D1 direction side) of the reflector 13, and the other surface 112 faces the bottom 131a side (D2 direction side) of the reflector 13.
  • the driver unit 11 (first driver unit) emits an acoustic signal AC1 (first acoustic signal) to the D1 direction side (one side) of the driver unit 11, and emits an acoustic signal AC2 (second acoustic signal) to the D2 direction side (other side) of the driver unit 11.
  • the acoustic signal AC1 (reproduced acoustic signal) emitted from the driver unit 11 is emitted outward from the open end 130 on the D1 direction side of the reflector 13.
  • a part of the acoustic signal AC1 is emitted directly from the driver unit 11 to the D1 direction side of the reflector 13.
  • At least another part of the acoustic signal AC1 is reflected by the inner wall surface 131 of the reflector 13 and then emitted from the open end 130 to the D1 direction side.
  • At least a part of the acoustic signal AC2 is reflected by the inner wall surface 131 of the reflector 13 and then emitted from the open end 130 to the D1 direction side.
  • a user located on the D1 direction side can hear the acoustic signal AC1 emitted from the open end 130 of the reflector 13.
  • the reflector 13 suppresses sound leakage of the acoustic signal AC1 to the back surface 132 side of the reflector 13.
  • the acoustic signal AC2 is an inverse phase signal of the acoustic signal AC1 or an approximation signal of the inverse phase signal. Therefore, at a specific position on the D1 direction side other than where the user is present (for example, a position behind the user), a part of the acoustic signal AC1 cancels out a part of the acoustic signal AC2, suppressing sound leakage of the acoustic signal AC1.
  • the driver unit 11 is disposed on the axis A1, and for example, it is desirable that the diaphragm 113 is disposed on the axis A1. More preferably, it is desirable that the center of the diaphragm 113 or its vicinity is disposed on the axis A1. In other words, it is desirable that the diaphragm 113 is disposed at the center or near the center of the above-mentioned paraboloid of revolution. This is because the sound pressure of the acoustic signal AC1 emitted from the open end 130 becomes axially symmetric or approximately axially symmetric with respect to the axis A1.
  • the driver unit 11 is disposed at the focal point or near the focal point of this paraboloid of revolution.
  • the directivity of the acoustic signal AC1 emitted from the open end 130 becomes high.
  • a point on a parabola constituting the paraboloid of revolution is (x, y)
  • a focal point of the paraboloid of revolution is P(0, p)
  • the driver unit 11 when the driver unit 11 is disposed near the focal point P(0, p) or focal point P(0, p) of the paraboloid of revolution, the directivity of the acoustic signal AC1 emitted from the open end 130 becomes high.
  • the driver unit 11 when the driver unit 11 is disposed at a position (0, q) that is shifted from the focal point P(0, p) or focal point P(0, p) of the paraboloid of revolution (p ⁇ q), the center of the traveling direction of the acoustic signal AC1 emitted from the open end 130 spreads outward with respect to the Y axis.
  • the directivity of the acoustic signal AC1 emitted from the reflector 13 is lower than when the driver unit 11 is disposed at the focus P(0,p) of the paraboloid of revolution or in the vicinity of the focus P(0,p).
  • a part of the acoustic signal AC2 is also emitted from the open end 130 in the D1 direction after being reflected by the inner wall surface 131 of the reflector 13.
  • the acoustic signal AC2 is an inverse phase signal of the acoustic signal AC1 or an approximation of the inverse phase signal.
  • the high-frequency components have short wavelengths and are less likely to cancel each other out. Therefore, on the D1 direction side, the sound pressure of the high-frequency components of the acoustic signal AC1 can be sufficiently secured.
  • the mid- and low-frequency components of the acoustic signals AC1 and AC2 emitted from the open end 130 have low directivity and are more likely to leak to the back surface 132.
  • the acoustic signal AC2 is an inverse phase signal of the acoustic signal AC1 or an approximation signal of the inverse phase signal, and these low-frequency components have long wavelengths and tend to cancel each other out.
  • the acoustic signal AC2 it is ideal that the difference between the propagation distance from the surface 111 on one side of the driver unit 11 to the position where sound leakage is to be suppressed and the propagation distance from the surface 112 on the other side of the driver unit 11 to the position where sound leakage is to be suppressed is an integer multiple (including the same) of the wavelengths of the acoustic signals AC1 and AC2.
  • the reflector 13 of this embodiment is provided with one or more sound holes 131b (reflector sound holes).
  • the sound hole 131b also serves to weaken the directivity of the high-frequency components of the acoustic signals AC1 and AC2. If the sound pressure of the high-frequency components is too high, it may be harsh to the ear, but by providing the sound hole 131b, the sound pressure of the high-frequency components of the acoustic signals AC1 and AC2 emitted in the D1 direction can be weakened.
  • the sound hole 131b may be circular or triangular, or a plurality of sound holes 131b with different shapes and sizes may be provided, or the sound hole 131b may be arranged in a biased manner at any position.
  • the sound hole 131b may be arranged in a biased manner in a direction in which sound leakage of the acoustic signal AC1 becomes a problem.
  • FIG. 1 and FIG. 1 illustrate an example in which four rectangular sound holes 131b are arranged in the reflector 13 symmetrically or approximately symmetrically with respect to the axis A1.
  • the sound hole 131b may be circular or triangular, or a plurality of sound holes 131b with different shapes and sizes may be provided, or the sound hole 131b may be arranged in a biased manner at any position.
  • the sound hole 131b may be arranged in a biased manner in a direction in which sound leakage of the acoustic signal AC1 becomes a problem.
  • the sound hole 131b is arranged near the D2 direction side (the other side) of the driver unit 11 (first driver unit) or the D2 direction side (the other side) of the driver unit 11 (first driver unit).
  • the acoustic signal AC1 emitted from the D1 direction side of the driver unit 11 is less likely to be emitted from the sound hole 131b, and the acoustic signal AC2 emitted from the D2 direction side of the driver unit 11 is more likely to be emitted from the sound hole 131b.
  • the sound hole 131b is, for example, a sound hole that penetrates the reflector 13, but this does not limit the present invention. As long as the acoustic signal inside the reflector 13 can be led out to the outside, the sound hole 131b does not have to be a through hole.
  • the edge shape of the open end of the sound hole 131b is quadrangular (when the open end is square) is illustrated, but this does not limit the present invention.
  • the edge shape of the open end of the sound hole 131b may be other shapes such as a circle, an ellipse, or a triangle.
  • the open end of the sound hole 131b may be mesh-like.
  • the acoustic signal AC1 (first acoustic signal) is emitted from the D1 direction side (one side) of the driver unit 11 (first driver unit), and the acoustic signal AC2 (second acoustic signal) is emitted from the D2 direction side (the other side) of the driver unit 11 (first driver unit), so that the attenuation rate ⁇ 11 of the acoustic signal AC1 (first acoustic signal) at the position P2 (second point) based on the position P1 (first point) can be set to a predetermined value ⁇ th or less, and the attenuation amount ⁇ 12 of the acoustic signal AC1 (first acoustic signal) at the position P2 (second point) based on the position P1 (first point) can be set to a predetermined value ⁇ th or more.
  • the position P1 (first point) is a predetermined point where the acoustic signal AC1 (first acoustic signal) arrives.
  • the position P2 (second point) is a predetermined point that is farther away from the acoustic signal output device 10 than the position P1 (first point).
  • the predetermined value ⁇ th is a value smaller (lower) than the attenuation rate ⁇ 21 of an arbitrary or specific acoustic signal (sound) due to air propagation at a position P2 (second position) based on the position P1 (first position).
  • the predetermined value ⁇ th is a value larger than the attenuation amount ⁇ 22 of an arbitrary or specific acoustic signal (sound) due to air propagation at a position P2 (second position) based on the position P1 (first position). That is, the acoustic signal output device 10 is designed so that the attenuation rate ⁇ 11 is equal to or smaller than a predetermined value ⁇ th smaller than the attenuation rate ⁇ 21 , or the attenuation amount ⁇ 12 is equal to or larger than a predetermined value ⁇ th larger than the attenuation amount ⁇ 22.
  • the acoustic signal AC1 is propagated through the air from the position P1 to the position P2, and is attenuated due to this air propagation and the acoustic signal AC2.
  • the attenuation rate ⁇ 11 is the ratio (AMP2(AC1)/ AMP1 (AC1)) of the magnitude AMP2 (AC1) of the acoustic signal AC1 at position P2 attenuated due to air propagation and acoustic signal AC2 to the magnitude AMP1 (AC1) of the acoustic signal AC1 at position P1.
  • the attenuation amount ⁇ 12 is the difference (
  • the attenuation rate ⁇ 21 is the ratio (AMP 2 (AC ar )/AMP 1 (AC ar )) of the magnitude AMP 2 (AC ar ) of the acoustic signal AC ar at position P2 attenuated due to air propagation (attenuated without being due to the acoustic signal AC2) to the magnitude AMP 1 (AC ar ) of the acoustic signal AC ar at position P1.
  • the attenuation amount ⁇ 22 is the difference (
  • the magnitude of the acoustic signal include the sound pressure of the acoustic signal or the energy of the acoustic signal.
  • the "sound leakage component” refers to, for example, a component of the acoustic signal AC1 emitted from the sound hole 161a that is likely to reach an area other than the user present in the D1 direction (for example, a person other than the user present in the D1 direction).
  • the "sound leakage component” may be a component of the acoustic signal AC1 that propagates outside a specific region on the D1 direction side, or may be a component that propagates outside the D1 direction side.
  • a sound hole 131aa (reflector sound hole) that is connected to the internal space of the housing 16 is provided on the bottom 131a side (D2 direction side) of the reflector 13.
  • the sound hole 131aa is, for example, a sound hole that penetrates the reflector 13, but this does not limit the present invention. As long as the acoustic signal in the internal space of the housing 16 can be guided to the inside of the reflector 13, the sound hole 131aa does not have to be a through hole. Details of the sound hole 131aa will be described later.
  • the material that constitutes the reflector 13 there are no limitations on the material that constitutes the reflector 13, but it is desirable that at least the inner wall surface 131 is made of a material that reflects acoustic signals.
  • the reflector 13 may be made of a rigid body such as synthetic resin or metal, or may be made of an elastic body such as rubber.
  • the housing 16 (second housing) is a hollow member having a wall on the outside, and is disposed outside the reflector 13.
  • the housing 16 in this embodiment is disposed on the D2 direction side of the reflector 13.
  • a driver unit 15 (second driver unit) is housed inside the housing 16.
  • the driver unit 15 in this example is fixed at a position a certain distance away from a wall 161 on the D1 direction side of the housing 16.
  • a hollow area AR0 is provided between an area AR1 inside the wall 161 of the housing 16 in this example and a surface 151 on the D1 direction side of the driver unit 15.
  • the wall of the housing 16 is provided with one or more sound holes 161a (third sound holes) that guide the acoustic signal AC3 (third acoustic signal) emitted from the driver unit 15 to the inside of the reflector 13 through the above-mentioned sound hole 131aa, and one or more sound holes 163a (fourth sound holes) that guide the acoustic signal AC4 (fourth acoustic signal) emitted from the driver unit 15 to the outside of the reflector 13 outside the housing 16.
  • a recess 161b is provided on the outside of the wall 161 on one side (D1 direction side) of the housing 16, and the outside of the bottom 131a of the reflector 13 is fixed to this recess 161b.
  • the sound hole 161a (third sound hole) is provided in this recess 161b and is connected to the sound hole 131aa (reflector sound hole) of the reflector 13 (FIGS. 1 and 4).
  • the acoustic signal AC3 emitted from the driver unit 15 to the area AR0 is guided to the inside of the reflector 13 by the sound hole 161a and the sound hole 131aa.
  • the acoustic signal AC3 guided to the inside of the reflector 13 is emitted from the open end 130 of the reflector 13 in the D1 direction.
  • the center of the sound hole 131aa (reflector sound hole) connected to the sound hole 161a (third sound hole), or the center of the multiple sound holes 131aa (reflector sound holes) connected to the single or multiple sound holes 161a (third sound holes) is located on the axis A1 (axis) or near the axis A1 (axis) (for example, FIG. 5). This is because the sound pressure of the acoustic signal AC3 emitted from the open end 130 of the reflector 13 is axially symmetric or approximately axially symmetric with respect to the axis A1.
  • the sound hole 163a faces the external space on the back surface 132 side of the reflector 13, and the acoustic signal AC4 emitted into the hollow area AR (internal space) of the housing 16 on the D2 direction side of the driver unit 15 is guided to the outside of the reflector 13 by the sound hole 163a.
  • the acoustic signal AC4 is an antiphase signal or an approximation signal of the antiphase signal of the acoustic signal AC3.
  • the acoustic signal AC3 is an in-phase signal or an approximation signal of the in-phase signal of the acoustic signal AC1
  • the acoustic signal AC4 is an in-phase signal or an approximation signal of the in-phase signal of the acoustic signal AC2. Therefore, at least a part of the acoustic signal AC4 emitted from the sound hole 163a cancels at least a part of the sound leakage components of the acoustic signals AC1 and AC3 emitted from the open end 130 of the reflector 13. This also makes it possible to suppress sound leakage, especially sound leakage on the low frequency side (acoustic signal AC3).
  • the sound hole 161a and the sound hole 163a are, for example, sound holes penetrating the wall of the housing 16, but this does not limit the present invention.
  • the acoustic signal AC3 can be led to the inside of the reflector 13 and the acoustic signal AC4 can be led to the outside of the reflector 13, the sound hole 161a and the sound hole 163a do not have to be through holes.
  • the shape of the housing 16 is rotationally symmetric (line symmetric) or approximately rotationally symmetric about the axis A1.
  • the housing 16 has a wall portion 161 arranged on one side (D1 direction side) of the driver unit 15, a wall portion 162 arranged on the other side (D2 direction side) of the driver unit 15, and a wall portion 163 surrounding the space sandwiched between the wall portion 161 and the wall portion 162, centered on the axis A1 passing through the wall portion 161 and the wall portion 162 (FIGS. 1 and 4).
  • the housing 16 has a substantially cylindrical shape with both end faces.
  • the housing 16 may have a substantially dome shape with walls at the ends, a hollow substantially cubic shape, or other three-dimensional shapes.
  • the housing 16 may be made of a rigid body such as synthetic resin or metal, or may be made of an elastic body such as rubber.
  • a user located in a specific area on the D1 direction side can hear the acoustic signals AC1 and AC3 emitted from the open end 130 of the reflector 13.
  • the acoustic signal AC2 which is an opposite phase signal of the acoustic signal AC1 or an approximation of the opposite phase signal, is emitted from the sound hole 131b.
  • the acoustic signal AC4 which is an opposite phase signal of the acoustic signal AC3 or an approximation of the opposite phase signal, is emitted from the sound hole 163a.
  • a part of the emitted acoustic signals AC2 and AC4 cancels out a part of the acoustic signals AC1 and AC3 (sound leakage components) emitted from the open end 130 of the reflector 13.
  • a part of the acoustic signal AC2 mainly cancels out a part of the acoustic signal AC1
  • a part of the acoustic signal AC4 mainly cancels out a part of the acoustic signal AC3.
  • an acoustic signal AC1 (first acoustic signal) is emitted from the D1 direction side (one side) of the driver unit 11 (first driver unit)
  • an acoustic signal AC2 (second acoustic signal) is emitted from the D2 direction side (the other side) of the driver unit 11 (first driver unit)
  • an acoustic signal AC3 (third acoustic signal) is emitted from the D1 direction side (one side) of the driver unit 15 (second driver unit)
  • the fourth acoustic signal is emitted from the D2 direction side (the other side) of the driver unit 15 (second driver unit).
  • the position P1 (first point) is a predetermined point where the emitted acoustic signal AC1 (first acoustic signal) and the acoustic signal AC3 (third acoustic signal) arrive.
  • the position P2 (second point) is a predetermined point farther away from the acoustic signal output device 10 than the position P1 (first point).
  • the predetermined value ⁇ th is a value smaller (lower) than the attenuation rate ⁇ 21 of an arbitrary or specific acoustic signal (sound) due to air propagation at the position P2 (second point) based on the position P1 (first point).
  • the predetermined value ⁇ th is a value larger than the attenuation amount ⁇ 22 of an arbitrary or specific acoustic signal (sound) due to air propagation at the position P2 (second point) based on the position P1 (first point). That is, the acoustic signal output device 10 of this embodiment is designed so that the attenuation rate ⁇ 112 is equal to or less than a predetermined value ⁇ th smaller than the attenuation rate ⁇ 21 , or the attenuation amount ⁇ 122 is equal to or greater than a predetermined value ⁇ th larger than the attenuation amount ⁇ 22.
  • the attenuation rate ⁇ 112 is a ratio (AMP 2 (AC1)/AMP 1 (AC1)) of the magnitude AMP 2 (AC1) of the acoustic signal AC1 at position P2 attenuated due to air propagation and the acoustic signals AC2 and AC4 to the magnitude AMP 1 (AC1) of the acoustic signal AC1 at position P1, or a ratio (AMP 2 (AC3)/AMP 1 (AC13)) of the magnitude AMP 2 (AC3) of the acoustic signal AC3 at position P2 attenuated due to air propagation and the acoustic signals AC2 and AC4 to the magnitude AMP 1 (AC3) of the acoustic signal AC3 at position P1 .
  • the attenuation rate ⁇ 112 may be a statistical value (average value, sum, multiplication value, etc.) of the ratio (AMP 2 (AC1)/AMP 1 (AC1)) and the ratio (AMP 2 (AC3)/AMP 1 (AC13)).
  • the attenuation amount ⁇ 122 is the difference (
  • the attenuation amount ⁇ 122 may be a statistical value (average value, sum value, multiplication value, etc.) of the difference (
  • the acoustic signals AC2 and AC4 are not assumed, an arbitrary or specific acoustic signal AC ar propagated through the air from the position P1 to the position P2 is attenuated due to air propagation, not due to the acoustic signals AC2 and AC4.
  • the attenuation rate ⁇ 21 is the ratio (AMP2(ACar)/ AMP1 ( ACar )) of the magnitude AMP2 ( ACar ) of the acoustic signal ACar at position P2 attenuated due to air propagation (attenuation without being due to the acoustic signal AC2) to the magnitude AMP1 ( ACar ) of the acoustic signal ACar at position P1.
  • the attenuation amount ⁇ 22 is the difference (
  • the size of the driver unit 11 (first driver unit) is smaller than the size of the driver unit 15 (second driver unit).
  • the driver unit 11 is arranged inside the reflector 13, and the acoustic signals AC1 and AC2 emitted from the driver unit 11 are emitted from the open end 130 and the sound hole 131b of the reflector 13.
  • the driver unit 15 is housed inside the housing 16 located outside the reflector 13, and the acoustic signal AC3 emitted from the driver unit 15 is introduced inside the reflector 13 and is further emitted from the open end 130 of the reflector 13.
  • the acoustic signal AC4 emitted from the driver unit 15 is emitted from the sound hole 163a of the housing 16 to the outside of the reflector 13. Therefore, the difference between the propagation distance until the acoustic signal AC1 emitted from the D1 direction side of the diaphragm 113 of the driver unit 11 reaches position P2 (second point) and the propagation distance until the acoustic signal AC2 (second acoustic signal) emitted from the D2 direction side (other side) of the diaphragm 113 reaches position P2 (second point) is smaller than the difference between the propagation distance until the acoustic signal AC3 emitted from the D1 direction side (one side) of the diaphragm 153 of the driver unit 15 reaches position P2 (second point) and the propagation distance until the acoustic signal AC4 emitted from the D2 direction side (other side) of the diaphragm 153 reaches position P2 (second point).
  • the driver unit 11 side has a higher sound leakage prevention effect than the driver unit 15 side.
  • the higher the frequency the more susceptible it is to the difference in propagation distance, so the higher the frequency, the lower the sound leakage prevention effect tends to be.
  • the driver unit 11 is mainly responsible for high-frequency sound signals among the reproduced sound signals
  • the driver unit 15 is mainly responsible for low-frequency sound signals among the reproduced sound signals. Therefore, in terms of frequency, the driver unit 15 side has a higher sound leakage prevention effect than the driver unit 11 side. These characteristics of the sound leakage prevention effect make it possible to obtain a sufficient sound leakage prevention effect in a wide frequency band.
  • the diameter of the diaphragm 153 (second diaphragm) of the driver unit 15 is larger than the diameter of the diaphragm (first diaphragm) of the driver unit 11, the driver unit 15 side can increase the low-frequency sound pressure compared to the driver unit 11. As a result, it is possible to obtain sufficient low-frequency sound pressure while suppressing sound leakage.
  • the sound hole 161a (third sound hole) illustrated here is provided in an area AR1 (first area) of the wall 161 arranged on one side of the driver unit 15 (the D1 direction side where the acoustic signal AC3 is emitted) (FIGS. 1 and 4). That is, the sound hole 161a opens in the D1 direction (first direction) along the axis A1 and communicates with the sound hole 131aa of the reflector 13.
  • the sound hole 163a (fourth sound hole) illustrated here is provided in an area AR3 of the wall 163 that contacts the area AR between the area AR1 (first area) of the wall 161 of the housing 16 and an area AR2 (second area) of the wall 162 arranged on the D2 direction side of the driver unit 15 (the other side where the acoustic signal AC4 is emitted).
  • the sound hole 161a (third sound hole) is provided on the D1 direction side (first direction side) of the housing 16
  • the sound hole 163a fourth sound hole is provided on the D12 direction side (second direction side) of the housing 16.
  • the housing 16 has a wall 161 arranged on one side (D1 direction side) of the driver unit 15, a wall 162 arranged on the other side (D2 direction side) of the driver unit 15, and a wall 163 (side surface) surrounding the space between the wall 161 and the wall 162, centered on an axis A1 along the emission direction (D1 direction) of the acoustic signal AC3 passing through the wall 161 and the wall 162 (FIG. 4), the sound hole 161a (third sound hole) is provided in the wall 161, and the sound hole 163a (fourth sound hole) is provided in the wall 163 (side surface). In this example, it is desirable not to provide a sound hole on the wall 162 side of the housing 16.
  • the sound pressure level of the acoustic signal AC4 emitted from the housing 16 will exceed the level necessary to offset the sound leakage component of the acoustic signal AC3, and the excess will be perceived as sound leakage.
  • the sound hole 161a illustrated here is disposed on or near the axis A1 along the emission direction (D1 direction) of the acoustic signal AC3.
  • the axis A1 in this example passes through the center or near the center of the area AR1 (first area) of the wall 161 disposed on one side (D1 direction side) of the driver unit 15 of the housing 16.
  • the axis A1 is an axis extending in the D1 direction through the central area of the housing 16. That is, the sound hole 161a in this example is provided at the central position of the area AR1 of the wall 161 of the housing 16.
  • the edge shape of the open end of the sound hole 161a is a circle (the open end is circular).
  • the edge shape of the open end of the sound hole 161a may be other shapes such as an ellipse, a rectangle, or a triangle.
  • the open end of the sound hole 161a may also be mesh-like.
  • the open end of the sound hole 161a may be composed of multiple holes.
  • an example is shown in which four sound holes 161a are provided in the area AR1 (first area) of the wall 161 of the housing 16.
  • one or more sound holes 161a may be provided in the area AR1 (first area) of the wall 161 of the housing 16, or another number of sound holes 161a may be provided.
  • the sound hole 163a (fourth sound hole) be disposed in a manner that takes into consideration, for example, the following points.
  • the sound hole 163a is positioned so that the propagation path of the sound leakage component of the sound signal AC3 to be cancelled out overlaps with the propagation path of the sound signal AC4 emitted from the sound hole 163a.
  • the propagation area of the acoustic signal AC4 emitted from the sound hole 163a and the frequency characteristics of the housing 16 vary depending on the opening area of the sound hole 163a.
  • the frequency characteristics of the housing 16 affect the frequency characteristics of the acoustic signal AC4 emitted from the sound hole 163a, i.e., the amplitude at each frequency.
  • the opening area of the sound hole 163a is determined so that the sound leakage component is cancelled out by the acoustic signal AC4 emitted from the sound hole 163a in the area where the sound leakage component is to be cancelled out.
  • the sound hole 163a (fourth sound hole) be configured as follows. For example, as illustrated in FIG. 3 and FIG.
  • a plurality of sound holes 163a are provided along a circumference (circle) C1 centered on an axis A1 along the emission direction of an acoustic signal AC3 (first acoustic signal).
  • the acoustic signal AC4 is emitted radially (radially centered on the axis A1) from the sound holes 163a to the outside.
  • the sound leakage component of the acoustic signal AC3 is also emitted radially (radially centered on the axis A1) from the sound hole 161a to the outside.
  • the sound leakage component of the acoustic signal AC3 can be appropriately canceled by the acoustic signal AC4.
  • a plurality of sound holes 163a are provided on the circumference C1 .
  • the plurality of sound holes 163a are provided along the circumference C1, and all the sound holes 163a do not necessarily have to be strictly arranged on the circumference C1.
  • the sum of the opening areas of the sound holes 163a (fourth sound holes) provided along a first arc region, which is one of the unit arc regions, is the same or approximately the same as the sum of the opening areas of the sound holes 163a (fourth sound holes) provided along a second arc region, which is one of the unit arc regions excluding the first arc region.
  • a first arc region which is one of the unit arc regions
  • a second arc region which is one of the unit arc regions excluding the first arc region.
  • the sum of the opening areas of the sound holes 163a (fourth sound holes) provided along a first arc region (for example, unit arc region C1-1) which is one of the unit arc regions C1-1, ..., C1-4 is the same or approximately the same as the sum of the opening areas of the sound holes 163a (fourth sound holes) provided along a second arc region (for example, unit arc region C1-2) which is one of the unit arc regions excluding the first arc region.
  • the sound pressure distribution of the acoustic signal AC4 emitted from the sound hole 163a provided along the first arc region and the sound pressure distribution of the acoustic signal AC4 emitted from the sound hole 163a provided along the second arc region are axially symmetrical or approximately axially symmetrical with respect to the axis A1.
  • the sums of the opening areas of the sound holes 163a (fourth sound holes) provided along each unit arc region are all the same or approximately the same for each unit arc region.
  • the sound pressure distribution of the acoustic signal AC4 emitted from the sound hole 163a is axially symmetrical or approximately axially symmetrical with respect to the axis A1. This allows the sound leakage component of the acoustic signal AC3 to be more appropriately canceled out by the acoustic signal AC4.
  • the multiple sound holes 163a are arranged along the circumference C1 with the same shape, size, and spacing.
  • the sound leakage component of the acoustic signal AC3 can be more appropriately cancelled out by the acoustic signal AC4.
  • this is not a limitation of the present invention.
  • the edge of the open end of the sound hole 163a is shaped like a rectangle (the open end is square), but this does not limit the present invention.
  • the edge of the open end of the sound hole 163a may be shaped like a circle, ellipse, triangle, or other shape.
  • the open end of the sound hole 163a may also be mesh-like.
  • the open end of the sound hole 163a may be composed of multiple holes.
  • FIG. 8A illustrates a horn speaker in which a horn 13' is attached to the driver unit 11'.
  • the opening area of the mouth part of the horn 13' is S 1 '
  • the opening area of the throat part of the horn 13' is S 2 '
  • the length of the horn 13' is S 3 '.
  • the driver unit 11' is attached to the mouth part of the horn 13'.
  • the cutoff frequency f c of this horn speaker is expressed as the following formula (1).
  • m represents the spreading coefficient
  • c represents the speed of sound.
  • FIG. 8B illustrates the reflector 13 in which the driver unit 11 of this embodiment is arranged.
  • the opening area S 1 of the open end 130 of the reflector 13 is regarded as the opening area S 1 ' of the mouth part of the horn
  • the area S 2 of the face 111 of the driver unit 11 is regarded as the opening area S 2 ' of the throat part of the horn
  • the length S 3 from the face 111 of the driver unit 11 to the open end 130 of the reflector 13 is regarded as the length S 3 ' of the horn.
  • the cutoff frequency f c of the reflector 13 in which the driver unit 11 is arranged can be approximated as shown in the following formula (5).
  • reflector 13 in which driver unit 11 is arranged can be regarded as a speaker with a cutoff frequency f c expressed by equation (5).
  • an output signal output from the reproduction device 100 is input to a signal separation device 101.
  • the signal separation device 101 separates the input output signal into a high-frequency band signal on the high-frequency side and a low-frequency band signal on the low-frequency side.
  • the output signal is branched into two, and the branched output signals are input to a high-pass filter 101a and a low-pass filter 101b, respectively.
  • the high-pass filter 101a attenuates the low-frequency side of the input output signal to obtain a high-frequency band signal and output it.
  • the low-pass filter 101b attenuates the high-frequency side of the input output signal to obtain a low-frequency band signal and output it.
  • the high-frequency band signal is input to a driver unit 11 of the acoustic signal output device 10, and the driver unit 11 emits an acoustic signal AC1 in the D1 direction and an acoustic signal AC2 in the D2 direction.
  • the low-frequency band signal is input to the driver unit 15 of the acoustic signal output device 10, and the driver unit 15 emits an acoustic signal AC3 in the D1 direction and an acoustic signal AC4 in the D2 direction.
  • the cross frequency is f cross
  • the driver unit 11 emits high-frequency band acoustic signals AC1 and AC2 having sufficient sound pressure at frequencies equal to or higher than the cross frequency f cross
  • the driver unit 15 emits low-frequency band acoustic signals AC3 and AC4 having sufficient sound pressure at frequencies equal to or lower than the cross frequency f cross
  • the low-pass filter 101b outputs a low-frequency band signal having sufficient sound pressure at frequencies equal to or lower than the cross frequency f cross
  • the high-pass filter 101a outputs a high-frequency band signal having sufficient sound pressure at frequencies equal to or higher than the cross frequency f cross .
  • the cross frequency f cross is a frequency lower than the cutoff frequency f c of the speaker composed of the driver unit 11 and the reflector 13 expressed by the formula (5). That is, it is desirable to set the cross frequency f cross between the high-frequency band and the low-frequency band to be lower than the cutoff frequency f c expressed by the formula ( 5 ).
  • the cross frequency f cross is 1000 [Hz] or close to it, and the cutoff frequency f c is a frequency higher than 1000 [Hz]. This allows sufficient sound pressure to be obtained in the high frequency band.
  • the cross frequency f cross and the cutoff frequency f c may be determined so that a full-band signal having the desired frequency characteristics is obtained at the listening point of the user located in the D1 direction.
  • Figures 10A, 10B, 11A, 11B, and 12 show graphs (radar charts) showing the sound pressure at frequencies of 805 Hz, 1000 Hz, 1995 Hz, 3981 Hz, and 7943 Hz of the acoustic signal observed around the acoustic signal output device 10 of this embodiment, respectively.
  • 0 [deg] represents the D1 direction
  • 180 [deg] represents the D2 direction
  • each line represents the sound pressure level at a position 100 mm, 200 mm, 300 mm, and 400 mm away from the acoustic signal output device 10 in each direction.
  • the closer to the center the lower the sound pressure level, and the closer to the outside, the higher the sound pressure level.
  • Figures 13A to 15 show graphs representing the frequency characteristics of acoustic signals observed around the acoustic signal output device 10 of this embodiment.
  • the horizontal axis of these graphs represents frequency [Hz], and the vertical axis represents sound pressure level [dB].
  • Each line represents the sound pressure level [dB] in each direction [deg] and each relative position [mm] with respect to the acoustic signal output device 10.
  • "aaa deg_bbb mm_cl” in the legends of these graphs represents the sound pressure level [dB] observed at a direction of aaa [deg] and a relative position of bbb [mm] with respect to the acoustic signal output device 10.
  • the acoustic signal output device 10 of this embodiment can ensure sufficient sound pressure in a specific area on the D1 side over a wide frequency band, while adequately suppressing sound leakage to other positions.
  • sound leakage to the surroundings can be suppressed over a wide frequency band, including high frequencies.
  • a single sound hole 161a may be provided in the area AR1 of the wall part 161 of the housing 16, or a plurality of sound holes 161a may be provided, or a single sound hole 131aa connected to the sound hole 161a may be provided on the bottom part 131a side of the reflector 13, or a plurality of sound holes 131aa may be provided.
  • the reflector 13 may be biased to an eccentric position (a position on the axis A12 parallel to the axis A1, which is offset from the axis A1) (hereinafter, simply referred to as "eccentric position") that is offset from the center (center position) of the housing 16.
  • eccentric position a position on the axis A12 parallel to the axis A1, which is offset from the axis A1
  • the reflector 13 may be biased on the axis A12.
  • one sound hole 161a and one sound hole 131aa may be disposed on the axis A1
  • the reflector 13 may be offset to the axis A12.
  • the reflector 13 may be offset to the housing 16, and one sound hole 161a and one sound hole 131aa.
  • the distribution and opening area of the sound holes 163a may be offset accordingly.
  • the number of sound holes 163a provided along the unit arc regions C1-3 and C1-4 far from the axis A12 is smaller than the number of sound holes 163a provided along the unit arc regions C1-1 and C1-2 closer to the axis A12.
  • the opening area of each of the sound holes 163a provided along the unit arc regions C1-3 and C1-4 far from the axis A12 is smaller than the opening area of each of the sound holes 163a provided along the unit arc regions C1-1 and C1-2 closer to the axis A12.
  • the sum of the opening areas of the sound holes 163a (second sound holes) provided along the first arc region (e.g., C1-3 or C1-4), which is one of the unit arc regions, is smaller than the sum of the opening areas of the sound holes 163a provided along the second arc region (e.g., C1-1 or C-2), which is one of the unit arc regions closer to the axis A12 than the first arc region.
  • the reflector 13 is disposed at an eccentric position, the distribution of the acoustic signal AC3 emitted to the outside from the open end 130 of the reflector 13 is also biased to the eccentric position.
  • the distribution of the acoustic signal AC4 emitted to the outside from the sound hole 163a can also be biased to the eccentric position. This allows the emitted acoustic signal AC4 to fully cancel out the sound leakage component of the acoustic signal AC3.
  • the driver unit 11 (first driver unit) is housed inside a housing 12 (first housing) different from the housing 16 (second housing), and the housing 12 which thus houses the driver unit 11 inside may be positioned inside the reflector 13.
  • the housing 12 is a hollow member having a wall on the outside, and the sound holes 121a and 123a are provided in the wall, and the driver unit 11 is stored inside.
  • the driver unit 11 is fixed to the end of the housing 12 on the D1 direction side.
  • the shape of the housing 12 is rotationally symmetric (line symmetric) or approximately rotationally symmetric about the axis A1. This makes it easy to provide the sound hole 123a so that the variation in the energy of the acoustic signal emitted from the housing 12 is small for each direction.
  • the housing 12 has a first end surface that is a wall portion 121 arranged on one side (D1 direction side) of the driver unit 11, a second end surface that is a wall portion 122 arranged on the other side (D2 direction side) of the driver unit 11, and a side surface that is a wall portion 123 that surrounds the space sandwiched between the first end surface and the second end surface, centered on the axis A1 passing through the first end surface and the second end surface.
  • the housing 12 has a substantially cylindrical shape with both end faces.
  • the housing 12 may have a substantially dome-shaped shape with walls at the ends, a hollow substantially cubic shape, or other three-dimensional shapes.
  • the housing 12 may be made of a rigid body such as synthetic resin or metal, or may be made of an elastic body such as rubber.
  • the wall of the housing 12 is provided with a sound hole 121a (first sound hole) that guides the acoustic signal AC1 (first acoustic signal) emitted from the driver unit 11 to the outside (inside the reflector 13), and a sound hole 123a (second sound hole) that guides the acoustic signal AC2 (second acoustic signal) emitted from the driver unit 11 to the outside (inside the reflector 13).
  • the sound hole 121a and the sound hole 123a are, for example, through holes that penetrate the wall of the housing 12, but this does not limit the present invention. As long as the acoustic signal AC1 and the acoustic signal AC2 can be guided to the outside (inside the reflector 13), respectively, the sound hole 121a and the sound hole 123a do not have to be through holes.
  • the sound hole 121a (first sound hole) illustrated here is provided in an area AR1 (first area) of the wall 121 arranged on one side of the driver unit 11 (the D1 direction side where the acoustic signal AC1 is emitted) (FIGS. 18, 19, 20A, 20B, 21). That is, the sound hole 121a opens in the D1 direction (first direction) along the axis A1.
  • the sound hole 123a (second sound hole) illustrated here is provided in an area AR3' of the wall 123 that contacts an area AR' between an area AR1' of the wall 121 of the housing 12 and an area AR2' of the wall 122 arranged on the D2 direction side of the driver unit 11 (the other side where the acoustic signal AC2 is emitted).
  • the sound hole 121a first sound hole
  • the sound hole 123a second sound hole
  • the housing 12 has a wall portion 121 arranged on one side (D1 direction side) of the driver unit 11, a wall portion 122 arranged on the other side (D2 direction side) of the driver unit 11, and a wall portion 123 (side surface) that surrounds the space sandwiched between wall portions 121 and 122 and is centered on an axis A1 along the emission direction (D1 direction) of the acoustic signal AC1 that passes through wall portions 121 and 122 ( Figure 18), sound hole 121a (first sound hole) is provided in wall portion 121, and sound hole 123a (second sound hole) is provided in wall portion 123 (side surface).
  • the sound hole 121a illustrated here is disposed on or near the axis A1 along the emission direction (D1 direction) of the acoustic signal AC1. That is, the sound hole 121a in this example is provided at the center position of the area AR1 of the wall portion 121 of the housing 12.
  • the edge shape of the open end of the sound hole 121a is circular (the open end is circular).
  • the edge shape of the open end of the sound hole 121a may be other shapes such as an ellipse, a square, a triangle, etc.
  • the open end of the sound hole 121a may be mesh-like.
  • the open end of the sound hole 121a may be composed of multiple holes.
  • one sound hole 121a is provided in the area AR1 (first area) of the wall portion 121 of the housing 12.
  • this does not limit the present invention.
  • two or more sound holes 121a may be provided in area AR1 (first area) of wall 121 of housing 12.
  • multiple sound holes 123a are provided along a circumference (circle) C1 centered on an axis A1 along the emission direction of the acoustic signal AC1 (first acoustic signal).
  • a circumference C1 centered on an axis A1 along the emission direction of the acoustic signal AC1 (first acoustic signal).
  • AC1 first acoustic signal
  • the sum of the opening areas of the sound holes 123a (second sound holes) provided along a first arc region, which is any of the unit arc regions, is the same or approximately the same as the sum of the opening areas of the sound holes 123a (second sound holes) provided along a second arc region, which is any of the unit arc regions excluding the first arc region.
  • the multiple sound holes 123a are arranged along the circumference C1 with the same shape, size, and spacing.
  • the sound leakage component of the acoustic signal AC1 can be more appropriately cancelled out by the acoustic signal AC2.
  • this is not a limitation of the present invention.
  • the edge of the open end of the sound hole 123a is shaped like a rectangle (the open end is square), but this does not limit the present invention.
  • the edge of the open end of the sound hole 123a may be shaped like a circle, ellipse, triangle, or other shape.
  • the open end of the sound hole 123a may also be mesh-like.
  • the open end of the sound hole 123a may be composed of multiple holes.
  • the housing 12 is fixed to the inner wall surface 131 of the reflector 13 via the support 14.
  • the sound hole 121a side of the housing 12 arranged inside the reflector 13 faces the open end 130 side (D1 direction side) of the reflector 13, and the wall portion 122 on the other side faces the bottom 131a side (D2 direction side) of the reflector 13. It is preferable that at least some of the sound holes 123a of the housing 12 are provided in a position facing the sound hole 131b of the reflector 13.
  • the housing 16 and the driver unit 15 may be omitted.
  • the sound hole 131aa may be omitted.
  • a cutout portion (slit portion) 231b that opens the inside of the reflector 13 to the outside may be provided in a part of the open end 130 side of the reflector 13.
  • the acoustic signal AC1 and the acoustic signal AC2 are emitted from the open end 130 of the reflector 13.
  • the acoustic signal AC2 is an inverse phase signal of the acoustic signal AC1 or an approximate signal of the inverse phase signal.
  • a part of the acoustic signal AC1 and a part of the acoustic signal AC2 cancel each other out, thereby suppressing sound leakage of the acoustic signal AC1 at the position P22.
  • the high-frequency components of the acoustic signal AC1 and the acoustic signal AC2 are difficult to cancel each other out, and the acoustic signal AC2 may emphasize the acoustic signal AC1 at the position P22, thereby promoting sound leakage.
  • the size of the cutout portion 231b may be designed so that the sound pressure of the acoustic signal AC2 (second acoustic signal) at a specific position P22 in the open end 130 direction of the reflector 13 is equal to or lower than a predetermined level.
  • the size of the cutout portion 231b may be designed so that the sound pressure of the acoustic signal AC2 (second acoustic signal) at the position P22 at a frequency equal to or higher than a predetermined frequency is equal to or lower than a predetermined level.
  • An example of the cutout portion 231b is shown below.
  • cutout portion 231b (cutout portion 231b-SW)> 23 and 24 show an acoustic signal output device 20 in which, instead of the sound hole 131b, a horizontally elongated cutout portion 231b-SW that opens the inside of the reflector 13 to the outside is provided in a part of the open end 130 side of the reflector 13. That is, the shape of the cutout portion 231b-SW in this example is longer in the D4 direction perpendicular to the D1-D2 direction than in the D1-D2 direction.
  • ⁇ Example 2 of cutout portion 231b (cutout portion 231b-LW)> 25 illustrates an acoustic signal output device 20 in which, instead of the sound hole 131b, a large vertical and horizontal cutout portion 231b-LW that opens the inside of the reflector 13 to the outside is provided in a part of the open end 130 side of the reflector 13. That is, the length of the cutout portion 231b-LW in this example in the D1-D2 direction is the same as the length of the cutout portion 231b-SW in Fig. 23 in the D1-D2 direction, but the length of the cutout portion 231b-LW in the D4 direction is longer than the length of the cutout portion 231b-SW in the D4 direction.
  • Example 3 of cutout portion 231b (cutout portion 231b-LN)> 26 illustrates an acoustic signal output device 20 in which, instead of the sound hole 131b, a vertically elongated cutout portion 231b-LN that opens the inside of the reflector 13 to the outside is provided in a part of the open end 130 side of the reflector 13. That is, the length in the D1-D2 direction of the shape of the cutout portion 231b-LN in this example is the same as the length in the D1-D2 direction of the cutout portion 231b-LW in FIG. 25, but the length in the D4 direction of the cutout portion 231b-LN is shorter than the length in the D4 direction of the cutout portion 231b-LW.
  • the line where "L25-aaaa” is “L25-61065" represents the measurement result of the acoustic signal output device 20 provided with the cutout portion 231b-SW ( Figure 24).
  • the line where "L25-aaaa” is “L25-61063” represents the measurement result of the acoustic signal output device 20 provided with the notch 231b-LW (FIG. 25).
  • the line where "L25-aaaaa” is “L25-61064" represents the measurement result of the acoustic signal output device 20 provided with the notch 231b-LN (FIG. 26).
  • "bbb mm” represents the distance from the acoustic signal output device 20 to the measurement position.
  • c° represents the direction of the measurement position relative to the acoustic signal output device 20.
  • c° being 0° represents the direction of the measurement position relative to the acoustic signal output device 20 being the D1 direction.
  • c° being 90° represents the direction of the measurement position relative to the acoustic signal output device 20 being perpendicular to the D1-D2 direction.
  • c° being 180° represents the direction of the measurement position relative to the acoustic signal output device 20 being the D2 direction.
  • sound leakage can be adjusted by changing the size and shape of the cutout portion 231b.
  • a vertically elongated cutout portion 231b-LN that opens the inside of the reflector 13 to the outside may be provided in a portion of the open end 130 side of the reflector 13.
  • a part of the reflector 13 may be used as a diaphragm of the driver unit (second driver unit). This allows the overall size to be reduced.
  • driver unit second driver unit
  • the 29 has a concave reflector 13 with a paraboloid of revolution or a surface approximating a paraboloid of revolution on the inside, a driver unit 11, 35 (speaker driver unit, driver) that converts the output signal output from the playback device into an acoustic signal and outputs it, a housing 36 that houses the driver unit 35 inside, and a support 14 for positioning the driver unit 11 inside the reflector 13.
  • the reflector 13 is positioned on the wall 361 side of the housing 36 in the D1 direction, and the bottom 131a (part) of the reflector 13 also functions as the diaphragm 353 of the driver unit 35.
  • the driver unit 35 emits an acoustic signal AC3 (third acoustic signal) from a surface 353a on the D1 direction side (one side) by vibrating the diaphragm 353, which is the bottom 131a of the reflector 13, in the D1 direction side (one side), and emits an acoustic signal AC4 (fourth acoustic signal) from the other surface 353b in the D2 direction side (the other side) by this vibration.
  • At least a part of the inner wall surface 131 of the reflector 13 is a paraboloid of revolution or a surface approximating a paraboloid of revolution, and this paraboloid of revolution has a shape obtained by rotating a parabola around the axis A1 (specific axis), and it is desirable that the diaphragm 353 is the bottom 131a part of the reflector 13 arranged on or near the axis A1. This makes the sound pressure of the acoustic signal AC3 emitted from the open end 130 of the reflector 13 axially symmetric or approximately axially symmetric with respect to the axis A1.
  • the single or multiple sound holes 131b are provided at positions of the reflector 13 other than the diaphragm 353. This allows high sound pressure acoustic signals AC3 and AC4 to be emitted from the diaphragm 353.
  • FIG. 29 shows an example in which the driver unit 11 is not housed in the housing 12.
  • the driver unit 11 (first driver unit) may be housed inside a housing 12 (first housing) that is different from the housing 36 (second housing), and the housing 12 housing the driver unit 11 inside in this manner may be disposed inside the reflector 13 (see variant 2 of the first embodiment).
  • the present invention is not limited to the above-described embodiment.
  • the bottom 131a side of the reflector 13 is fixed to the wall 161 of the housing 16.
  • the bottom 131a side of the reflector 13 may be integral with the wall 161 of the housing 16.
  • the driver unit 11 may be disposed at or near the focal point of the paraboloid of revolution of the reflector 13, the driver unit 11 may be disposed in another position.
  • the driver unit 11 may be attached to the bottom 131a side of the reflector 13.
  • the reflector 13 may also be horn-shaped or have some other shape.
  • the high-pass filter 101a may be omitted from the signal separation device 101 illustrated in FIG. 9A.
  • the acoustic signals AC1 and AC2 emitted from the driver unit 11 tend to cancel each other out due to interference with each other in the mid-low frequency band, so the sound pressure level on the mid-low frequency side due to the acoustic signals AC1 and AC2 at the observation point decreases.
  • the acoustic signals AC1 and AC2 do not cancel each other out sufficiently in the high frequency band, so the sound pressure level on the high frequency side due to the acoustic signals AC1 and AC2 at the observation point is high. This characteristic plays a role equivalent to that of a high-pass filter.
  • the sound pressure level on the mid-low frequency side due to the acoustic signals AC1 and AC2 observed at the observation point is suppressed on the mid-low frequency side, but is not suppressed much on the high frequency side (FIG. 30B).
  • This effect is particularly noticeable when the driver unit 11 is housed inside the housing 12 that has the sound holes 121a and 123a as described above (for example, modified example 2 of the first embodiment). Therefore, especially when the driver unit 11 is housed inside the housing 12 that has the sound holes 121a and 123a, the effect on the characteristics is small even if the high-pass filter 101a is omitted.
  • the output signal output from the playback device 100 is input to the signal separation device 101, which branches the input output signal into two.
  • the branched output signals are input to the driver unit 11 and the low-pass filter 101b, respectively.
  • the driver unit 11 Based on the input output signal, the driver unit 11 emits an acoustic signal AC1 in the D1 direction and emits an acoustic signal AC2 in the D2 direction.
  • the low-pass filter 101b attenuates the high-frequency side of the input output signal to obtain and output a low-frequency band signal.
  • the low-frequency band signal is input to either the driver unit 15 or 35 of the acoustic signal output device 10 to 30, and the driver unit 15 or 35 emits an acoustic signal AC3 in the D1 direction and emits an acoustic signal AC4 in the D2 direction.

Landscapes

  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Transducers For Ultrasonic Waves (AREA)
PCT/JP2022/041805 2022-11-10 2022-11-10 音響信号出力装置 Ceased WO2024100816A1 (ja)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2024556929A JPWO2024100816A1 (https=) 2022-11-10 2022-11-10
PCT/JP2022/041805 WO2024100816A1 (ja) 2022-11-10 2022-11-10 音響信号出力装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2022/041805 WO2024100816A1 (ja) 2022-11-10 2022-11-10 音響信号出力装置

Publications (1)

Publication Number Publication Date
WO2024100816A1 true WO2024100816A1 (ja) 2024-05-16

Family

ID=91032071

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2022/041805 Ceased WO2024100816A1 (ja) 2022-11-10 2022-11-10 音響信号出力装置

Country Status (2)

Country Link
JP (1) JPWO2024100816A1 (https=)
WO (1) WO2024100816A1 (https=)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008211642A (ja) * 2007-02-27 2008-09-11 Kyushu Institute Of Technology ヘッドホン装置
JP2022531254A (ja) * 2019-04-30 2022-07-06 シェンツェン・ショックス・カンパニー・リミテッド 音響出力装置
JP2022546523A (ja) * 2019-09-02 2022-11-04 ボーズ・コーポレーション 開放型オーディオデバイス

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008211642A (ja) * 2007-02-27 2008-09-11 Kyushu Institute Of Technology ヘッドホン装置
JP2022531254A (ja) * 2019-04-30 2022-07-06 シェンツェン・ショックス・カンパニー・リミテッド 音響出力装置
JP2022546523A (ja) * 2019-09-02 2022-11-04 ボーズ・コーポレーション 開放型オーディオデバイス

Also Published As

Publication number Publication date
JPWO2024100816A1 (https=) 2024-05-16

Similar Documents

Publication Publication Date Title
US11159870B2 (en) Acoustic output apparatus
US11589171B2 (en) Systems and methods for suppressing sound leakage
JP7794971B2 (ja) 音響信号出力装置
JP2014187679A (ja) イヤホンマイク
JP7740359B2 (ja) 音響信号出力装置
JPWO2023243379A5 (https=)
WO2024100816A1 (ja) 音響信号出力装置
WO2024100817A1 (ja) 音響信号出力装置
WO2024100815A1 (ja) 音響信号出力装置
JP6932029B2 (ja) ホーンスピーカー、スピーカーユニット、メガホン、アダプター、及び放送システム
CN110012397B (zh) 一种扬声器
JP7785641B2 (ja) 音響信号出力装置
JP7768381B2 (ja) 音響信号出力装置
JP7827560B2 (ja) 音響信号出力装置
WO2024252550A1 (ja) ヘッドホン装置、音響信号出力方法
WO2024100822A1 (ja) 音響信号出力装置
JP7758166B2 (ja) 音響信号出力装置
JP2023182166A (ja) 音響信号出力装置
WO2024252549A1 (ja) ヘッドホン装置、音響信号出力方法
JPWO2024100817A5 (https=)
WO2024180763A1 (ja) 音響信号出力システム、および音響信号出力方法
JP2022073436A (ja) イヤホン
JPWO2024150792A5 (https=)
WO2024150792A1 (ja) 音響信号出力装置
HK40064150A (en) Acoustic output apparatus

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22965141

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2024556929

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 22965141

Country of ref document: EP

Kind code of ref document: A1