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DESCRIPTION JP2007067514

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DESCRIPTION JP2007067514
To provide a speaker device capable of forming a wide angle and narrow angle sound field.
SOLUTION: An audible sound signal generated by a reproduction signal generating means is
outputted through a switching means, an ultrasonic wave carrier wave signal generated by an
ultrasonic wave transmitting means, and an ultrasonic wave carrier wave generated through the
switching means. An audible sound signal modulated by a carrier wave modulation means to
generate a modulated carrier wave signal, and an ultrasonic speaker outputting the modulated
carrier wave signal, and an output destination from the switching means described above is an
audible sound speaker By switching to the carrier wave modulation means, the directivity angle
of the output voice can be changed. [Selected figure] Figure 1
Speaker device
[0001]
The present invention relates to a speaker device capable of changing the angle of directivity of
the sound to be output, and in particular, the directivity of the sound to be output by switching
the output destination of the audible sound signal generated by the reproduction signal
generating means by the switching means. The present invention relates to a speaker device
capable of changing an angle.
[0002]
The speaker apparatus which can achieve a parametric effect is proposed using an ultrasonic
speaker (for example, refer patent document 1).
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1
[0003]
The schematic configuration of the speaker device will be described with reference to FIG.
FIG. 9 is a schematic diagram for explaining the configuration of a conventional speaker device.
[0004]
In this conventional speaker device, an ultrasonic signal which is a carrier wave generated by the
carrier wave transmission source 42 and an audible sound signal generated by the audio
processing unit 45 are modulated by the modulator 43, and this modulated signal is converted to
the ultrasonic speaker 44. By generating a secondary sound wave of an audible sound by a nonlinear phenomenon of ultrasonic waves, a parametric effect can be obtained.
[0005]
Further, in the speaker device, the distance between the speaker and a person who listens to the
voice is measured by the human sensor 47 by the sensor control unit 46, and the transmission
frequency of the carrier wave is selected by the frequency storage unit 41 according to the
distance. The carrier wave transmission source 42 has a function of changing the frequency of
the carrier wave transmitted.
[0006]
Sound waves in the ultrasonic range generally have a characteristic that the amount of
attenuation when propagating in the air increases as the frequency becomes higher, and the
reach distance becomes shorter. Can change the frequency of the carrier wave to change the
reach of voice.
[0007]
Therefore, in this conventional speaker device, when the frequency of the carrier wave generated
by the carrier wave source 42 is set high, the reach of the sound wave output from the ultrasonic
speaker 44 becomes short, and when the frequency is lowered, the reach is increased. Can
control the distance at which the sound can be heard.
[0008]
JP 2005-33372 A (pages 3-5, FIG. 1)
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2
[0009]
However, although the conventional speaker device is configured to be able to control the reach
distance of voice as described above, it is not possible to control the angle of directivity of voice
with this device configuration as it is.
That is, when using the electronic device equipped with this conventional speaker device, there
arises a disadvantage that the directivity angle can not be changed when it is desired to give a
voice to a plurality of persons.
[0010]
Therefore, with the electronic device equipped with this conventional speaker device, the user
can only use it in a predetermined sound field area, and one electronic device changes the
directivity angle. It was not possible to cope with the purpose of
[0011]
An object of the present invention is to solve the above-mentioned problems and to provide a
speaker device capable of forming an audible sound field in which the angle of the audible sound
field of the directivity of the speaker device is controlled.
[0012]
In order to achieve the above object, the speaker device of the present invention basically adopts
the following configuration.
[0013]
The speaker device according to the present invention comprises an audible sound speaker for
outputting an audible sound signal generated by the reproduction signal generating means
through the switching means, a carrier wave signal of ultrasonic waves generated by the
ultrasonic wave transmitting means, and the switching means. An audible sound signal output by
the carrier wave modulation means to be modulated by a carrier wave modulation means to
generate a modulated carrier wave signal, and an ultrasonic speaker outputting the modulated
carrier wave signal, and the output destination from the switching means is for audible sound By
switching between the speaker and the carrier wave modulation means, it is possible to change
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3
the angle of directivity of the outputted sound.
[0014]
Further, in the speaker device of the present invention, the above-mentioned audible sound
speaker and ultrasonic speaker are disposed on the diaphragm and the diaphragm so that the
resonance point is in both the supersonic band and the ultrasonic band. The resonance point is
constituted by one speaker having the constituted piezoelectric element and the ultrasonic wave
transmission means is selected by the frequency selection means, and the carrier signal at the
resonance point is selected. It is characterized by generating.
[0015]
By adopting the speaker device of the present invention, it is possible to make the directivity
angle of the voice to be transmitted variable, so that the user does not want to hear the voice
around the device user, if necessary. It can be used for both of the users of the device who want
to hear the sound.
[0016]
Hereinafter, the speaker device in the embodiment of the present invention and the operation
thereof will be described using the drawings.
[0017]
First, the configuration of the speaker device of the present invention will be described with
reference to FIG.
FIG. 1 is a schematic view showing a configuration example of a speaker device of the present
invention.
[0018]
The speaker device according to the present invention shown in the present drawing has an
audible range speaker 15 and an ultrasonic speaker 14, and when outputting audio from the
audible range speaker 15, the audio signal to be reproduced by the reproduction signal
generating means 10 An audible sound signal is reproduced as a sound source, the audio range
speaker 15 is selected by the switching means 11, and the audible sound signal is output as it is.
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[0019]
When sound is output from the ultrasonic speaker 14, the ultrasonic wave oscillation means 12
generates a carrier wave signal of the ultrasonic wave, and the audible sound signal generated by
the reproduction signal generation means 10 is changed to the carrier wave by the switching
means 11. Input to the modulation means 13.
The carrier wave modulation means 13 frequency-modulates or phase-modulates the carrier
wave signal using the audible sound signal, and the diaphragm based on the coarse / fine period
of the modulated carrier wave signal obtained by the carrier wave modulation means 13 by the
ultrasonic speaker 14. Can vibrate to emit directional sound.
[0020]
When the output from the ultrasonic speaker 14 is insufficient, an amplifier for amplifying the
modulated carrier signal is further provided between the carrier modulation means 13 and the
ultrasonic speaker 14 to amplify the electric signal. It is good also as a form
[0021]
Similarly, an amplifier may be provided between the switching means 11 and the audible range
speaker 15 to amplify the electric signal.
[0022]
The speaker device of the present invention configured in this way is set to output the sound
wave from the ultrasonic speaker 14 by controlling the switching means 11 when the device user
wants to listen to the voice only by the user. Use in a narrow directivity sound field.
Further, when it is desired to let the surrounding people hear the voice simultaneously, the
switching means 11 may be controlled to output sound waves from the audible range speaker 15
and used in a wide-angle sound field.
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[0023]
Next, a method of changing the directivity of sound by the speaker device of the present
invention will be described based on FIG.
FIG. 2 is a schematic drawing for illustrating the action of sound field formation when the
speaker device of the present invention is used.
Note that, in the drawing, the supersonic sound range speaker 15 and the ultrasonic speaker 14
in the speaker device are overlapped and arranged, and only the portion is shown.
[0024]
In general, sound waves are characterized in that the straightness becomes stronger and the
directivity becomes narrower as the frequency becomes higher.
Therefore, as shown in FIG. 2, the modulated carrier signal, which is the sound wave of the
ultrasonic wave area created by the carrier wave modulation means 13 shown in FIG. 1 and
output from the ultrasonic speaker 14, forms the narrow directional sound field 16. It will be.
[0025]
On the other hand, when the audible sound signal is directly transmitted to the audible range
speaker 15 and output without passing through the carrier wave modulation means 13 by the
switching means 11 (see FIG. 1), the reproduction signal generation means 10 The listening
signal (sound wave in the audible range) is output as it is.
Since the audible sound signal has a relatively low frequency, the sound propagates through the
air at a wide angle to form a wide-angle sound field 17.
[0026]
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6
Therefore, as described above, when the user does not want to hear the sound around the device
user, the switching means 11 is controlled to output the sound from the ultrasonic speaker 14
and the narrow directivity sound field 16 is generated. It can be used.
Further, when it is desired to let the surrounding person other than the user hear the sound at
the same time, the sound can be output from the audio range speaker 15 so that the wide-angle
sound field 17 can be formed and used.
[0027]
Next, the operation principle of the ultrasonic speaker 14 in the speaker device of the present
invention will be described with reference to FIG.
FIG. 3 is a drawing for explaining a specific signal processing method used for the ultrasonic
speaker 14 constituting the present invention, and FIG. 3 (a) shows the reproduction signal
generating means 10 (see FIG. 1). FIG. 6B is a diagram showing an audible sound signal 18 to be
generated, FIG. 6B is a diagram showing a carrier wave signal 19 generated by the ultrasonic
wave oscillation means 12, and FIG. FIG. 6 is a diagram showing a modulated carrier signal 20
generated as a result.
[0028]
The method of signal processing in the speaker device of the present invention is, first, as shown
in FIG. 3 (a), an audible sound signal 18 generated by an audible sound source (reproduction
signal generating means 10 shown in FIG. 1). The carrier wave signal 19 in the ultrasonic band
shown in b) is modulated by the frequency modulation method or phase modulation method
performed by the carrier wave modulation means 13 to produce a modulated carrier wave signal
20 as shown in FIG. 3 (c).
In this modulated carrier signal 20, a carrier signal 19 of ultrasonic waves of a fixed cycle is
modulated in accordance with the amplitude of the audible sound signal 18, the amplitude of the
waveform is the same, and the cycle is partially different.
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[0029]
The frequency modulation method adopted by the carrier modulation means 13 shown above
changes the angular frequency of the carrier signal 19 in proportion to the amplitude of the AC
signal of the audible sound signal 18 in FIG. Is a method of creating a modulated carrier signal
20.
[0030]
In addition, it is preferable to use a frequency of at least 30 kHz or more for the carrier wave
signal 19 of the ultrasonic band used in the present invention.
In general, ultrasonic waves are in the frequency band of 18 to 20 kHz or more, which is said to
be inaudible to the human ear.
However, since the carrier wave signal 19 less than 30 kHz is too close to the audible sound
frequency, even if the carrier wave signal 19 is modulated by the above-mentioned audible sound
signal 18, the degree of expansion and contraction of the carrier wave becomes small.
Therefore, in this band, an audible sound which can be recognized by the user is difficult to
reproduce, and even if it is reproduced, the sound becomes very low in sound pressure and
hardly audible to the user.
In addition, the frequency may be 20 kHz or less when the frequency of the modulated carrier
signal 20 is expanded. In this case, the modulated carrier signal 20 is audible in the audible
range, so that there is a problem that it can be heard.
[0031]
Furthermore, in the case of performing the above-described frequency modulation, it is
preferable to frequency modulate the carrier signal with a modulation degree of 0.1 to 30 kHz.
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It adjusts the modulation frequency by the audible sound to be played, and when adjusting the
audible sound to be reproduced cleanly without distortion, the distortion of the audible sound to
be reproduced when the modulation degree becomes 30 kHz or more causes the sound to be
loudly broken This makes it difficult for the user to listen.
If the frequency is less than 0.1 kHz, the modulation is too low and the audible sound is not
reproduced.
[0032]
Further, the phase modulation method which can be performed instead of the frequency
modulation described above changes the phase of the carrier signal 19 in proportion to the
amplitude of the alternating current signal of the audible sound signal 18 and stretches the
carrier. It is a method of creating the signal 20. The carrier signal 19 can be converted into the
modulated carrier signal 20 having a waveform having an expansion / contraction portion by
either of the frequency modulation and the phase modulation.
[0033]
Also in the carrier wave signal 19 of the ultrasonic band used in this phase modulation, it is
preferable to use the frequency of 30 kHz or more described above, for the same reason as
described above.
[0034]
When the above-described phase modulation is performed, it is preferable to modulate the
carrier wave with a modulation phase of 0.1 to 25 rag.
It adjusts the modulation phase by the audible sound to be played, and when adjusting the
audible sound so that it is reproduced cleanly without distortion, distortion of the audible sound
to be reproduced is too loud and split and sounds clean when the modulation is more than 25
rag It is because it can not be reproduced by In addition, the modulation is too low at 0.1 rag or
less, and the audible sound is not reproduced.
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[0035]
Next, the principle of audible sound reproduction will be described with reference to FIGS. 4 (a)
and 4 (b). FIG. 4 (a) is an explanatory view showing the state of the coarse / fine cycle of the
modulated carrier signal 20 transmitted from the ultrasonic speaker 14 constituting the present
invention, and FIG. 4 (b) shows the coarse / fine cycle of the user. It is explanatory drawing which
shows the principle until it hears to an ear.
[0036]
When the generated modulated carrier signal 20 (see FIG. 3C) is output from the ultrasonic
speaker 14 to the atmosphere as shown in FIG. 4A, the vibration of the diaphragm of the
ultrasonic speaker 14 causes the air to A coarse / dense state can be generated to generate an air
pressure corresponding to the waveform of the modulated carrier signal 20 shown in FIG. 3 (c).
As a result, as shown in FIG. 4 (a), the modulated carrier signal 20 emitted to the atmosphere
includes the high air pressure portion 21 and the low air pressure low portion 22 resulting from
the fine vibration in the ultrasonic band. generate.
[0037]
When this waveform reaches the user's ear, the user can not hear the pressure vibration of air in
the ultrasonic band, but can hear only the pressure vibration in the audible range. Therefore, as
shown in FIG. 4 (b), only the area of the high pressure part 21 and the low part 22 is recognized,
and the user can recognize it as a voice. This is because the user's ear acts as a kind of low pass
filter, so the user of the speaker device of the present invention can extract the vibration of the
audible range from the vibration of the ultrasonic band and can hear the voice. It is
[0038]
Here, the principle of forming a directional sound field will be described again with reference to
FIG. FIG. 5 is a schematic diagram for explaining the directivity principle in the speaker device of
the present invention.
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[0039]
Generally, as a vibration frequency is increased gradually from an audible range to an ultrasonic
wave range, as the vibration frequency increases, a region centered on the central axis 23 of the
vibrating flat plate is increased. It is known that the high sound pressure area 25 with high sound
pressure 24 comes to be concentrated.
[0040]
This phenomenon is also applicable to the ultrasonic speaker 14 used in the present invention,
and the sound pressure is extremely low outside the high sound pressure area 25 so that the
sound wave transmitted from the ultrasonic speaker 14 propagates a long distance. Will not be
able to
Therefore, when it is far from the ultrasonic speaker 14, the sound propagates only in the high
sound pressure area 25, and as a result, it has narrow directivity.
[0041]
As described above, since the modulated carrier signal 20 output from the ultrasonic speaker 14
used in the present invention is a signal in the ultrasonic band, the modulated carrier signal 20
does not spread in front of the ultrasonic speaker 14 in a wide angle, but has a narrow
directivity. Ultrasonic waves can be transmitted.
[0042]
Therefore, the user of the speaker device of the present invention can hear audible sound only
within the narrow range where the modulated carrier signal 20 propagates, when it is desired to
output narrow directional voice, and outside this range You will be able to make it impossible to
hear.
[0043]
Also, when an audible sound signal is output from the audible range speaker 15 shown in FIG. 2
previously, a conventionally known technique is that sound waves propagate at a wide angle and
the voice can be heard over a wide range because the frequency is low. Since it is good if it
applies, the detailed explanation here is omitted.
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[0044]
Here, specific configurations of the ultrasonic speaker and the audible range speaker in the
present invention will be described.
First, the ultrasonic speaker will be described.
FIG. 6 is a view showing an embodiment of an ultrasonic speaker for embodying the speaker
device of the present invention.
[0045]
As shown in FIG. 6, the ultrasonic speaker 14 shown above is configured to vibrate the
diaphragm 26 to transmit ultrasonic waves.
A piezoelectric element 27 is attached to the diaphragm 26 of the speaker as a vibration source.
A resonator 28 may be attached to the surface of the diaphragm 26 to increase the sound
pressure to be emitted.
[0046]
In the speaker, the electrodes 30a and 30b are fixed to a base 29 to which the diaphragm 26 is
fixed, and a piezoelectric element 27 is attached to the tip of the electrodes 30a and 30b using
insulating adhesives 31a and 31b. It has become. Furthermore, the piezoelectric element 27 is
connected to the electrodes 30a and 30b by the lead wires 32a and 32b, so that the piezoelectric
element 27 can be vibrated by a signal from an external electric circuit.
[0047]
In this way, at least one ultrasonic speaker may be used to output the modulated carrier signal in
the ultrasonic range, but when the audio signal to be reproduced is small, a plurality of ultrasonic
speakers are used to form an array. It may be an ultrasonic speaker unit arranged side by side.
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[0048]
Next, the form of the audible range speaker applicable to the speaker device of the present
invention will be described.
Although the audio range speaker 15 used in the present invention is not particularly shown
here, a voice coil type speaker or a piezoelectric speaker, which is usually used as a speaker for
reproducing supersonic sound, may be used. I will omit a brief explanation.
[0049]
As described above, according to the present invention, a wide-angle sound field and a narrow
directivity sound field can be selected and formed. Therefore, it is possible to provide a speaker
device in which the directivity angle can be varied according to the situation of the user.
[0050]
If the small and thin speaker device with such an effect is mounted on an electronic device such
as a mobile phone, a portable information terminal, a portable TV, or a personal computer, the
wide-angle and narrow-angle sound fields can be provided according to the needs of the user. It
can be an electronic device that can be arbitrarily controlled.
[0051]
Next, another embodiment used for the speaker device of the present invention will be described.
First, the operation of the speaker device according to this embodiment will be described. FIG. 7
is a drawing showing a phenomenon that the sound pressure increases or decreases when the
frequency given to the piezoelectric element 27 which is the vibration source of the speaker is
changed.
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[0052]
Generally, the resonance point of the piezoelectric element 27 has an apex at which the sound
pressure becomes high at an interval from the low frequency side to the primary, secondary, and
tertiary as shown by the arrow in FIG. In this embodiment, the case of using the primary
resonance point 33 on the low frequency side and the secondary resonance point 34 appearing
on the high frequency side will be described.
[0053]
Here, the ultrasonic speaker 14 is configured using the piezoelectric element 27 in which the
primary resonance point 33 is in the audible range, and the high-order resonance points after the
secondary resonance point 34 are in the ultrasonic range. By adopting such a configuration, it is
possible to output sound waves in two frequency bands of an audible range and an ultrasonic
range. Therefore, if the configuration of this embodiment is applied, it is not necessary to use the
two speakers of the ultrasonic speaker 14 and the audio range speaker 15 shown in the
embodiment 1, but the directivity of the sound output from one speaker The angle of can be
changed arbitrarily.
[0054]
A driving method in this case will be described with reference to a schematic view of FIG. FIG. 8
is a schematic view showing the configuration of the speaker device of the present invention.
[0055]
As shown in FIG. 8, the speaker device in the present embodiment is provided with a speaker 35
for both bands as a speaker capable of outputting two kinds of sound waves of an audible range
and an ultrasonic range for sound wave output. The switching means 11 and the carrier wave
modulation means 13 are connected. Further, a frequency selection means 36 is connected to the
ultrasonic wave transmission means 12 shown above, and this frequency selection means 36
selects secondary and subsequent resonance points as necessary. The effect of selecting this
resonance point will be described later.
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[0056]
Next, the operation of the speaker device of the present invention will be described using this
drawing. When a wide-angle sound field is to be formed, the audible sound signal to be
reproduced by the switching means 11 is directly propagated to the dual band speaker 35 and
the supersonic sound signal generated by the reproduction signal generating means 10 is
Output. At this time, since the primary resonance point is in the audible sound range, the audible
sound band is a band having a relatively high sound pressure. Therefore, with the device
configuration in this embodiment, an audible sound signal can be output from the dual-band
speaker 35 as it is.
[0057]
If it is desired to form a sound field with a narrower directivity, the frequency of the carrier wave
generated by the ultrasonic wave transmission means 12 may be a secondary resonance point in
the ultrasonic wave range (the third and fourth resonance points may be used arbitrarily. is
there. ) Is selected by the frequency selection means 36, a carrier wave of that frequency is
generated by the ultrasonic wave transmission means 12, and a modulated carrier wave signal
generated by modulating the audible sound signal by the carrier wave modulation means 13 is
used as the speaker 35 for both bands. Output from In this case, since the sound wave is in the
ultrasonic range, a narrow directivity sound field can be formed.
[0058]
In addition, when forming the sound field with narrow directivity, reaching the voice with
directivity by selecting the secondary resonance point and the above-mentioned third and fourth
or later resonance points arbitrarily by the frequency selection means 36 It is possible to change
the distance, which has a new effect not found in the first embodiment.
[0059]
Generally, as the frequency of the sound wave increases, the attenuation factor in air increases
and the reach distance decreases.
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15
Therefore, it is possible to shorten the arrival distance of the modulated carrier signal by
selecting the frequency of the higher frequency band of the third and fourth and subsequent
orders described above.
[0060]
In the above description of the present embodiment, an example is shown in which the primary
resonance point is in the audible range and the piezoelectric element 27 in which the second and
subsequent resonance points are provided in the ultrasonic range. Instead, it is sufficient if at
least the resonance point is in the audible range, for example, when the primary and secondary
resonance points are in the audible range, and the third and subsequent resonance points are in
the ultrasonic range. It is possible to use a primary or secondary resonance point, and use one of
the resonance points after the third resonance point when reproducing narrow directivity sound.
[0061]
In addition, when reproducing a wide directional voice, there is little distortion of the voice if it is
a frequency near the resonance point and sufficient sound pressure can be obtained, so it is not
necessary to use the frequency at the resonance point. It does not matter as reproduction by the
frequency of.
[0062]
As described above, in the speaker device according to the present embodiment, by utilizing the
plurality of resonance points possessed by the piezoelectric element 27, it is possible to select
and form a wide-angle sound field and a narrow directivity sound field. In addition to the effect of
the first embodiment that it is possible to provide a speaker device capable of reproducing sound
depending on the situation, it becomes possible to output an audio signal across an audible range
and an ultrasonic range from one speaker, The size of the apparatus can be further reduced as
compared with the configuration example of the first embodiment shown above.
[0063]
Further, as described above, if the resonance point in the ultrasonic wave region is arbitrarily
selected by the frequency selection means 36, a new effect not obtained in the first embodiment
can be obtained, in which the reachable distance of the directional voice can be changed. It will
play.
[0064]
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16
It is the schematic which shows the structural example of the speaker apparatus of this invention.
It is a figure which shows the state of the sound field formation in the speaker apparatus of this
invention.
It is drawing for demonstrating the drive principle of the ultrasonic speaker in the speaker
apparatus of this invention.
It is explanatory drawing which shows the effect | action of the ultrasonic speaker in the speaker
apparatus of this invention.
It is the schematic for demonstrating the directivity principle of the ultrasonic speaker in the
speaker apparatus of this invention. It is a structure sectional view of an ultrasonic speaker
showing one form for embodying a speaker device of the present invention. It is a figure for
demonstrating the effect | action in the other structural example of the speaker apparatus of this
invention. It is the schematic which shows the other structural example of the speaker apparatus
of this invention. It is the schematic which shows the structure of the conventional speaker
apparatus.
Explanation of sign
[0065]
DESCRIPTION OF SYMBOLS 10 reproduction signal generation means 11 switching means 12
ultrasonic oscillation means 13 carrier modulation means 14 ultrasonic speaker 15 audio range
speaker 16 narrow directional sound field 17 wide-angle sound field 18 audible sound signal 19
carrier signal 20 modulated carrier signal 21 pneumatic pressure High part 22 Low part of air
pressure 23 Central axis 24 Sound pressure 25 High sound pressure area 26 Diaphragm 27
Piezoelectric element 28 Resonator 29 Base 30a, 30b Electrode 31a, 31b Insulating adhesive
32a, 32b Lead wire 33 Primary resonance point 34 Secondary resonance point 35 Speaker for
both bands 36 Frequency selection means
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