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DESCRIPTION JP2016514424

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DESCRIPTION JP2016514424
Abstract Based on the listener's detected location relative to the loudspeaker array, a directivity
adjustment device is described which maintains a constant direct echo ratio. The directivity
adjustment apparatus may include a distance estimator, a directivity compensator and an array
processor. A distance estimator detects the distance between the speaker array and the listener.
Based on the detected distance, the directional compensator calculates a directivity indicator
from the beam generated by the speaker array that maintains a predetermined direct to echo
sound energy ratio. The array processor receives the calculated directivity indicator and
generates a set of audio signals that drive one or more of the transducers in the speaker array to
generate a beam pattern having the calculated directivity indicator To process each channel of
one sound program content.
Adjusting the beam pattern of a speaker array based on the location of one or more listeners
[0001]
This application claims the benefit of US Provisional Application No. 61 / 773,078, filed March 5,
2013, filed earlier on the date of filing.
[0002]
The audio device detects the listener's distance from the loudspeaker array and adjusts the
directivity index of the beam pattern output by the loudspeaker array to maintain a constant
direct to echo sound energy ratio.
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1
Other embodiments are also described.
[0003]
The speaker array may be variably driven to form a number of different beam patterns. The
beam pattern produced may be controlled and modified to change the direction and area in
which the sound is emitted. By using this nature of the loudspeaker array it is possible to control
several acoustic parameters. One such parameter is the direct to reverberant acoustic energy
ratio. This ratio compares the amount of sound that the listener receives directly from the
speaker array with the amount of sound that reaches the listener via the echoes from the walls
and other echoes in the room. For example, if the beam pattern produced by the loudspeaker
array is narrow and directed at the listener, the listener receives a large amount of direct energy
and a relatively small amount of reverberation energy, so the direct to echo ratio is large. It will
be. Alternatively, if the beam pattern produced by the loudspeaker array is wide, the listener will
receive a relatively large amount of sound reflected from the surface and the object, thus
reducing the direct echo ratio.
[0004]
The loudspeaker array may emit both direct sound energy and indirect or reverberant sound
energy towards the listener in the room or listening area. Direct sound energy is received directly
from the transducers in the speaker array, but the reverberant sound energy echoes from the
wall or surface of the room before reaching the listener. As the listener approaches the
loudspeaker array, the direct sound travel distance is significantly reduced, but the travel
distance of the reverberant sound is relatively unchanged or only slightly increased, so the direct
echo sound energy level is To rise.
[0005]
An embodiment of the present invention is a directivity adjustment device that maintains a
constant direct-to-echo ratio based on the detected location of the listener relative to the speaker
array. The directivity adjustment apparatus may include a distance estimator, a directivity
compensator and an array processor. A distance estimator detects the distance between the
speaker array and the listener. For example, the distance estimator may use (1) a user input
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device, (2) a microphone, (3) an infrared sensor and / or (4) a camera to determine the distance
between the loudspeaker array and the listener. Based on the detected distance, the directional
compensator calculates, from the beam generated by the loudspeaker array, a directional
indicator that maintains a predetermined direct to echo sound energy ratio. The direct to echo
ratio may be preset by the manufacturer or designer of the directivity adjustment device and may
vary based on the content of the sound program content to be reproduced. The array processor
receives the calculated directivity indicator and generates a set of audio signals that drive one or
more of the transducers in the speaker array to generate a beam pattern having the calculated
directivity indicator To process each channel of one sound program content. By maintaining a
constant direct to echo directivity ratio, the directivity adjustment device improves the
consistency and quality of the sound perceived by the listener.
[0006]
The above summary does not provide an exhaustive list of all aspects of the invention. The
present invention includes all possible systems and methods from all suitable combinations of
the various aspects summarized above, and those disclosed in the following detailed description,
particularly as filed with the application. It is believed that what is pointed out in the claims is
included. Such combinations have certain advantages not specifically described in the summary
above.
[0007]
Embodiments of the invention are illustrated by way of example and not by way of limitation in
the figures of the accompanying drawings in which like references indicate similar elements. It
should be noted that references in the present disclosure to the "an" or "one" embodiments of the
present invention are not necessarily to the same embodiment and that they mean at least one.
[0008]
FIG. 8 illustrates a beam conditioning system that adjusts the width of the generated sound
pattern based on the location of one or more listeners in a room or listening area, according to
one embodiment. FIG. 6 illustrates one loudspeaker array having multiple transducers housed in
a single cabinet, according to one embodiment. FIG. 7 illustrates another loudspeaker array
having a plurality of transducers housed in a single cabinet, according to another embodiment.
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FIG. 3 shows a block diagram of functional units and some hardware components making up the
directivity adjustment equipment according to one embodiment. FIG. 5 shows listeners located at
different distances from the loudspeaker array. FIG. 5 shows listeners located at different
distances from the loudspeaker array. FIG. 6 illustrates an example set of sound patterns with
various directional indicators that may be generated by a speaker array.
[0009]
Several embodiments are described with reference to the accompanying drawings. Although
many details are described, it will be appreciated that some embodiments of the present
invention may be practiced without these details. In other instances, well known circuits,
structures and techniques have not been shown in detail in order not to obscure the
understanding of the present description.
[0010]
FIG. 1 shows a beam conditioning system 1 for adjusting the width of the generated sound
pattern emitted by the speaker array 4 based on the location of one or more listeners 2 in a room
or listening area 3. Below, each element of the beam adjustment system 1 will be described as an
example.
[0011]
Beam conditioning system 1 includes one or more speaker arrays 4 that output sound into a
room or listening area 3. FIG. 2A shows one loudspeaker array 4 with a plurality of transducers 5
housed in a single cabinet 6. In this embodiment, the speaker array 4 has 32 separate
transducers 5 evenly aligned in 8 rows and 4 columns in the cabinet 5. In other embodiments,
different numbers of transducers 5 may be used with uniform spacing or non-uniform spacing.
For example, as shown in FIG. 2B, ten transducers 5 may be aligned in a single row within the
cabinet 6 to form a soundbar-style speaker array 4. Although the figures are aligned on a plane
or straight line, the transducers 5 may be aligned in a curved manner along an arc.
[0012]
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The transducer 5 may be any combination of a full range driver, a mid range driver, a subwoofer,
a woofer and a tweeter. Each of the transducers 5 may use a lightweight diaphragm, or a rigid
basket via a flexible suspension that moves a coil of wire (e.g. a voice coil) axially through a
cylindrical magnetic gap. Alternatively, a cone connected to a frame may be used. When an
electrical audio signal is applied to the voice coil, the current in the voice coil forms a magnetic
field, which makes the voice coil a variable electromagnet. The coil and the magnetic system of
the transducer 5 interact to generate a mechanical force that moves the coil (and hence the
attached cone) back and forth, thereby allowing the source (eg, signal processor, computer and
audio receiver) Regeneration of the sound under control of the applied electrical audio signal
from Although described herein as having a plurality of transducers 5 housed in a single cabinet
6, in other embodiments, a single speaker array 4 is housed in a cabinet 6. The transducer 5 may
be included.
[0013]
In such an embodiment, the loudspeaker array 4 is a stand alone loudspeaker. Each transducer 5
may be driven individually alone to generate a sound in response to an individual discrete audio
signal. The loudspeaker array 4 is reproduced towards the listener 2 by allowing the transducers
5 in the loudspeaker array 4 to be driven individually and individually according to different
parameters and settings (including delays and energy levels) A number of directional patterns
may be generated to simulate or better represent the corresponding channels of sound program
content. For example, beam patterns having different widths and directivity may be emitted by
the speaker array 4 based on the location of the listener 2 relative to the speaker array 4.
[0014]
As shown in FIGS. 2A and 2B, the speaker array 4 may include wires or conduits 7 that connect
to the directivity adjustment device 8. For example, each speaker array 4 may include two wiring
points, and the directivity adjustment device 8 may include complementary wiring points. The
wiring points may be coupling posts or spring clips provided at the rear of the speaker array 4
and the directivity adjustment device 8, respectively. The wires 7 are separately wound or
otherwise coupled to corresponding wiring points to electrically couple the speaker array 4 to
the directivity adjustment device 8.
[0015]
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In another embodiment, the speaker array 4 is coupled to the directivity adjustment device 8
using a wireless protocol such that the array 4 and the directivity adjustment device 8 maintain a
high frequency connection without being physically joined. . For example, the speaker array 4
may include a WiFi receiver that receives audio signals from a corresponding WiFi transmitter in
the directivity adjustment device 8. In some embodiments, the speaker array 4 may include an
integrated amplifier for driving the transducers 5 using wireless audio signals received from the
directivity adjustment device 8.
[0016]
Although shown as including two speaker arrays 4, audio system 1 may include any number of
speaker arrays 4 coupled to directivity adjustment device 8 via a wireless or wired connection.
For example, the audio system 1 may include six speaker arrays 4 representing front left
channel, front center channel, front right channel, back right surround channel, back left
surround channel and low frequency channel (eg, subwoofer). Hereinafter, the beam conditioning
system 1 is described as including a single speaker array 4. However, as mentioned above, it
should be understood that the system 1 may include multiple speaker arrays 4.
[0017]
FIG. 3 shows a block diagram of functional units and some hardware components making up the
directivity adjustment device 8 according to one embodiment. The components shown in FIG. 3
are typical elements included in the directivity adjustment device 8 and should not be interpreted
as excluding other components. Each element of FIG. 3 will be described below as an example.
[0018]
The directivity adjustment device 8 may include a plurality of inputs 10 for receiving one or
more channels of sound program content from one or more external audio sources 9 using
electrical, wireless or optical signals. The input 10 may be a set of digital inputs 10A and 10B
and analog inputs 10C and 10D, including a set of physical connectors disposed on the exposed
surface of the directivity adjustment device 8. For example, the input 10 may include a HighDefinition Multimedia Interface (HDMI (registered trademark)) input, an optical digital input
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(Toslink), a coaxial digital input and a phono input. In one embodiment, the directivity adjustment
device 8 receives an audio signal via a wireless connection with an external audio source 9. In
this embodiment, the input 10 comprises a wireless adapter that communicates with an external
audio source 9 using a wireless protocol. For example, the wireless adapter may be Bluetooth
(registered trademark), IEEE (registered trademark) 802.11x, Global System for Mobile
Communications (GSM (registered trademark)) for cellular mobile communication, cellular code
division multiplexing Communication may be possible using access (Code division multiple
access, CDMA) or Long Term Evolution (LTE).
[0019]
As shown in FIG. 1, the external audio source 9 may comprise a laptop computer. In other
embodiments, the external audio source 9 may be any device capable of transmitting one or
more channels of sound program content to the directivity adjustment device 8 via a wireless or
wired connection. For example, the external audio source 9 may be a desktop computer, a
portable communication device (e.g. a mobile phone or tablet computer), a streaming internet
music server, a digital video disc player, a Blu-ray Disc (R) player, a compact disc player or any
other Other similar audio output devices may be included.
[0020]
In one embodiment, an external audio source 9 and a directivity adjustment device 8 are
incorporated into one non-divisible unit. In this embodiment, the loudspeaker array 4 may also
be incorporated in the same unit. For example, the external audio source 9 and the directivity
adjustment device 8 may be provided in one computing unit with the loudspeaker array 4
integrated on the left and right sides of the unit.
[0021]
Here, returning to the directivity adjustment device 8, the general signal flow from the input 10
will be described. First, looking at the digital inputs 10A and 10B, when receiving digital audio
signals through the inputs 10A and / or 10B, the directivity adjustment device 8 uses electrical,
optical or wireless signals by using the decoders 11A and / or 11B. , Decode into a set of audio
channels representing sound program content. For example, decoder 11A may receive a single
signal (e.g., a 5.1 signal) comprising six audio channels and decode that signal into six audio
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channels. The decoder 11A may decode an audio signal encoded using any codec or technique
including Advanced Audio Coding (AAC), MPEG Audio Layer II, MPEG Audio Layer III and Free
Lossless Audio Codec (FLAC). It may be possible.
[0022]
Looking at analog inputs 10C and 10D, each analog signal received by analog inputs 10C and
10D represents a single audio channel of sound program content. Thus, multiple analog inputs
10C and 10D may be required to receive each channel of one sound program content. The audio
channel may be digitized by corresponding analog to digital converters 12A and 12B to form a
digital audio channel.
[0023]
The digital audio channels from each of the decoders 11A and 11B and the analog to digital
converters 12A and 12B are output to the multiplexer 13. The multiplexer 13 selectively outputs
a set of audio channels based on the control signal 14. The control signal 14 may be received
from a control circuit or processor in the directivity adjustment device 8 or an external device.
For example, the control circuit that controls the operation mode of the directivity adjustment
device 8 may output the control signal 14 to the multiplexer 13 to selectively output the set of
digital audio channels.
[0024]
The multiplexer 13 supplies the selected digital audio channel to the array processor 15. The
channels output by multiplexer 13 are processed by array processor 15 to generate a set of
processed audio channels. The processing may be performed in both time domain and frequency
domain using transforms such as Fast Fourier Transform (FFT). The array processor 15 may be a
special purpose processor such as an application-specific integrated circuit (ASIC), a general
purpose microprocessor, a field-programmable gate array (FPGA), a digital signal controller or
hardware logic. It may be a set of structures (eg, filters, arithmetic logic units and dedicated state
machines). The array processor 15 generates a set of signals for driving the transducers 5 in the
speaker array 4 based on the input from the distance estimator 16 and / or the directional
compensator 17.
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[0025]
The distance estimator 16 determines the distance of one or more listeners 2 from the speaker
array 4. FIG. 4A shows the listener 2 at a distance r A away from the loudspeaker array 4 in the
room 3. The distance estimator 16 determines the distance r A as the listener 2 moves in the
room 3 and while the sound is being emitted by the loudspeaker array 4. Although described in
the context of a single listener, the distance estimator 16 may determine the distance r A of the
plurality of listeners 2 in the room 3.
[0026]
Distance estimator 16 may use any device or algorithm that determines distance r. In one
embodiment, user input device 18 is coupled to distance estimator 16 to assist in determining
distance r. The user input device 18 enables the listener 2 to periodically input the distance r
from the loudspeaker array 4. For example, while watching a movie, listener 2 may initially sit on
a sofa at a distance of 6 feet from the speaker array 4. The listener 2 may input this six foot
distance into the distance estimator 16 using the user input device 18. In the middle of the
movie, the listener 2 may decide to move to a table at a distance of 10 feet from the speaker
array 4. Based on this movement, listener 2 may input this new distance r A into distance
estimator 16 using user input device 18. The user input device 18 may be a wired or wireless
keyboard, a mobile device, or any other similar device that allows the listener 2 to input a
distance into the distance estimator 16. In one embodiment, the input value is a non-numeric
value or a relative value. For example, the listener 2 may indicate that he is at a distance from or
near the speaker array 4 without indicating a specific distance.
[0027]
In another embodiment, a microphone 19 may be coupled to the distance estimator 16 to assist
in determining the distance r. In this embodiment, a microphone 19 is arranged with or adjacent
to the listener 2. The directivity adjustment device 8 drives the speaker array 4 to emit a set of
test sounds that are sensed by the microphone 19 and provided to the distance estimator 16 for
processing. The distance estimator 16 determines the propagation delay of the test sound when
moving from the loudspeaker array 4 to the microphone 19 based on the sensed sound. The
propagation delay may then be used to determine the distance r A from the speaker array 4 to
the listener 2.
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[0028]
The microphone 19 may be coupled to the distance estimator 16 using a wired or wireless
connection. In one embodiment, the microphone 19 is incorporated into a mobile device (e.g. a
mobile phone) and the sensed sound is a distance estimator using one or more wireless protocols
(e.g. Bluetooth and IEEE 802.11x) Sent to 16 The microphone 19 may be any type of
acoustoelectric transducer or sensor, including a microelectrical-mechanical system (MEMS)
microphone, a piezoelectric microphone, an electret condenser microphone or a dynamic
microphone. The microphone 19 provides a range of polar patterns such as cardioid,
omnidirectional and figure eight. In one embodiment, the polarity pattern of the microphone 19
may change continuously with time. Although shown and described as a single microphone 19,
in one embodiment, multiple microphones or microphone arrays may be used to detect sound in
the room 3.
[0029]
In another embodiment, camera 20 may be coupled to distance estimator 16 to assist in
determining distance r. The camera 20 may be a video camera or still image camera directed into
the room 3 and directed in the same direction as the speaker array 4. The camera 20 records a
set of video or still images in the area in front of the speaker array 4. Based on such recordings,
the camera 20 tracks the face or other body part of the listener 2 alone or together with the
distance estimator 16. The distance estimator 16 may determine the distance r A from the
speaker array 4 to the listener 2 based on this face / body tracking. In one embodiment, while
the speaker array 4 is outputting sound program content, the camera 20 periodically features the
listener 2 so that the distance r A can be updated and its accuracy maintained. To track. For
example, the camera 20 may continuously track the listener 2 while the music is being played
through the speaker array 4.
[0030]
The camera 20 may be coupled to the distance estimator 16 using a wired or wireless
connection. In one embodiment, the camera 20 is embedded in a mobile device (e.g., a mobile
phone) and the recorded video or still image uses one or more wireless protocols (e.g., Bluetooth
and IEEE 802.11x) It is sent to the distance estimator 16. Although illustrated and described as a
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single camera 20, in one embodiment, multiple cameras may be used to track the face / body.
[0031]
In yet another embodiment, one or more infrared (IR) sensors 21 are coupled to the distance
estimator 16. The IR sensor 21 captures IR light emitted from an object in the area in front of the
speaker array 4. Based on such sensed IR readings, the distance estimator 16 may determine the
distance r A from the speaker array 4 to the listener 2. In one embodiment, while the speaker
array 4 is outputting sound, the IR sensor 21 operates periodically so that the distance r A can be
updated and its accuracy maintained. For example, the IR sensor 21 may continuously track the
listener 2 while playing music through the speaker array 4.
[0032]
The infrared sensor 21 may be coupled to the distance estimator 16 using a wired or wireless
connection. In one embodiment, the infrared sensor 21 is incorporated into a mobile device (e.g.
a mobile phone) and the sensed infrared light readings use one or more wireless protocols (e.g.
Bluetooth and IEEE 802.11x) And transmitted to the distance estimator 16.
[0033]
Although described above in connection with a single listener 2, in one embodiment, the distance
estimator 16 may determine the distance r A between the plurality of listeners 2 and the speaker
array 4. In this embodiment, in order to adjust the sound emitted by the loudspeaker array 4, the
average distance r A between the listener 2 and the loudspeaker array 4 is used.
[0034]
Using any combination of the above techniques, the distance estimator 16 calculates the distance
r and supplies it to the directional compensator 17 for processing. The directional compensator
17 calculates a beam pattern that maintains a constant direct-to-echo sound ratio. 4A and 4B
show the change in the direct to echo sound ratio for listener 2 as the distance r increases.
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[0035]
In FIG. 4A, the distance of the listener 2 from the loudspeaker array 4 is r A. In this exemplary
situation, listener 2 receives the direct sound energy level D A from the loudspeaker array 4 and
the indirect or reverberant sound energy level R A after the original sound echoes from the
surface in the room 3 Receive from array 4 Distance r A may be considered as a direct sound
propagation distance, and distance g A may be considered as a echo sound propagation distance.
In one embodiment, the direct sound energy D A may be calculated as, and the echo sound
energy R A may be calculated. Here, T 60 represents the room reverberation time, V represents
the room functional volume, and DI represents the directivity index of the sound pattern emitted
by the speaker array 4 toward the listener 2. In this example, the direct sound energy level D A
exceeds the echo sound energy level R A because the direct sound travel distance to the listener
2 is shorter than the echo sound (ie, the propagation distance is shorter).
[0036]
As shown in FIG. 4B, when the listener 2 moves away from the speaker array 4 and the
propagation distance r B increases, a time for direct sound energy D B to diffuse before reaching
the listener 2 occurs. Due to the increase of the propagation distance r B, D B falls significantly
below D A. In contrast, as the listener 2 moves away from the loudspeaker array 4, the
propagation distance g B only slightly increases from the original distance g A. This minor
change in echo propagation distance reduces the echo energy slightly from R A to R B. The echo
ranges shown in FIGS. 4A and 4B are for illustrative purposes only. In some embodiments, this
echo range consists of hundreds of echoes, so that when listener 2 moves away from the
loudspeaker array 4 (eg, the source), listener 2 starts from the first echo point Going away (see
FIGS. 4A and 4B), listener 2 may actually be approaching other echoes (eg echoes from the back
wall), so that the entire echo energy is room 3 Less affected by the location of listener 2 within.
[0037]
As can be seen from FIGS. 4A and 4B, and as described above, when the listener 2 moves away
from the speaker array 4, the propagation distance of the reflected sound wave is only slightly
increased, but the propagation distance of the direct sound wave is that The direct to reverberant
energy ratio decreases because it increases relatively more than it does. To compensate for this
ratio change, the directivity index DI of the sound pattern emitted by the speaker array 4 may be
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changed based on the distance r to maintain a constant ratio of direct to reverberant sound
energy. For example, if the beam pattern produced by the loudspeaker array is narrow and
directed at the listener, the listener receives a large amount of direct energy and a relatively
small amount of reverberation energy, so the direct to echo ratio is large. It will be. Alternatively,
if the beam pattern produced by the loudspeaker array is wide, the listener will receive a
relatively large amount of sound reflected from the surface and the object, thus reducing the
direct echo ratio. By changing the directivity index DI of the sound pattern emitted by the
loudspeaker array 4, the amount of direct and reverberant sound emitted towards the listener 2
may be increased or decreased. As a result of this change of direct and reverberant sound, the
direct to reverberant energy ratio changes.
[0038]
As mentioned above, each of the transducers in the loudspeaker array 4 may be driven
independently according to different parameters and settings (delay and energy level). By
independently driving each of the transducers 5, the directivity adjustment device 8 may
generate various directivity patterns having different directivity indicators DI in order to
maintain a constant direct-to-echo energy ratio. Good. FIG. 5 shows an example set of sound
patterns with different directivity indicators. The leftmost pattern is omnidirectional and
corresponds to the low directivity index DI. The middle pattern is directed somewhat to listener 2
more, corresponding to the higher directivity index DI. The rightmost pattern is significantly
directed to the listener 2 and corresponds to the highest directivity index DI. The set of sound
patterns described is for illustrative purposes only, and in other embodiments other sound
patterns may be generated by the directivity adjustment device 8 and emitted by the speaker
array 4.
[0039]
In one embodiment, directivity compensator 17 may calculate a directivity pattern having an
associated directivity index DI that maintains a predetermined direct to echo energy ratio. The
default direct to reverberant energy ratio may be preset during manufacture of the directivity
adjustment device 8. For example, the manufacturer or designer of directivity adjustment device
8 may pre-set a 2: 1 direct to echo energy ratio. In this embodiment, the directivity compensator
17 maintains a directivity index DI that maintains a 2: 1 direct to echo energy ratio, taking into
account the detected distance r between the listener 2 and the speaker array 4. calculate.
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[0040]
After calculating the directivity index DI, the directivity compensator 17 supplies this value to the
array processor 15. As described above, the directivity compensator 17 continuously calculates
the directivity index DI for each channel of the sound program content reproduced by the
directivity adjustment device 8 when the listener 2 moves in the room 3 May be The audio
channel output by the multiplexer 13 is an array processor 15 to generate a set of audio signals
that drive one or more of the transducers 5 to generate a beam pattern having the calculated
directivity index DI. Processed by The processing may be performed in both time domain and
frequency domain using transforms such as Fast Fourier Transform (FFT).
[0041]
In one embodiment, the array processor 15 determines the transducers 5 in the loudspeaker
array 4 that output one or more audio segments based on the calculated directivity index DI
received from the directivity compensator 17. In this embodiment, the array processor 15 may
determine the delay and energy settings used to output the segment through the selected
transducer 5. The selection and control of the transducer 5, the set of delays and energy levels
allow the segments to be output according to the calculated directivity index DI which maintains
a preset direct to echo energy ratio.
[0042]
As shown in FIG. 3, processed segments of sound program content are passed from the array
processor 15 to one or more digital-to-analog converters 22 to generate one or more separate
analog signals. The analog signals generated by the digital to analog converter 22 are provided to
a power amplifier 23 to drive selected transducers 5 of the loudspeaker array 4.
[0043]
In one exemplary situation, the listener 2 may sit on a sofa opposite the speaker array 4. The
directivity adjustment device 8 may play the musical composition through the speaker array 4. In
this situation, the directivity adjustment device 8 may attempt to maintain a 1: 1 direct to echo
energy ratio. When music is started, the distance estimator 16 uses the camera 20 to detect that
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the listener 2 is 6 feet away from the loudspeaker array 4. Based on this distance, in order to
maintain a 1: 1 direct-to-echo energy ratio, the directional compensator 17 calculates that the
speaker array 4 must output a beam pattern having a directivity index DI of 4 dB. Do. The array
processor 15 is supplied with the calculated directivity index DI and processes the music to
output a 4 dB beam pattern. A few minutes later, with the aid of the camera 20, the distance
estimator 16 detects that the listener 2 is currently sitting 4 feet away from the loudspeaker
array 4. Accordingly, the directivity compensator 17 calculates that the loudspeaker array 4 must
output a beam pattern having a directivity index DI of 2 dB in order to maintain a 1: 1 direct-toecho energy ratio. Do. The array processor 15 is supplied with the updated directivity index and
processes the music to output a 2 dB beam pattern. After a few more minutes, the distance
estimator 16 with the help of the camera 20 detects that the listener 2 is currently sitting 10 feet
away from the loudspeaker array 4. Accordingly, the directional compensator 17 calculates that
the loudspeaker array 4 must output a beam pattern having a directivity index DI of 8 dB in
order to maintain a 1: 1 direct-to-echo energy ratio. Do. The array processor 15 is supplied with
the updated directivity indicator and processes the music to output a beam pattern of 8 dB. As
described in the exemplary situation above, the directivity adjustment device 8 is configured by
adjusting the directivity index DI of the beam pattern emitted by the loudspeaker array 4
regardless of the location of the listener 2 Maintain the direct-to-echo energy ratio.
[0044]
In one embodiment, various direct-to-echo energy ratios corresponding to the content of the
audio reproduced by the directivity adjustment device 8 are preset in the directivity adjustment
device 8. For example, audio content in a movie may have a desired direct-to-echo energy ratio
higher than background music in the movie. The following is an exemplary table of direct-to-echo
energy ratios that vary by content.
[0045]
The directional compensator 17 may simultaneously calculate an individual beam pattern with
an associated directivity indicator DI which maintains the corresponding direct echo ratio of the
audio segments in the individual stream or channel. For example, the sound program content of a
movie may have multiple audio streams or channels. Each channel may include a separate
feature or type of audio. For example, a movie may include five audio channels corresponding to
a front left channel, a front center channel, a front right channel, a back right surround and a
back left surround. In this example, the front center channel may include foreground audio, the
front left and right channels may include background music, and the back left and right surround
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channels may include sound effects. Using the exemplary direct-to-echo energy ratios shown in
the above table, directivity compensator 17 maintains a 4: 1 direct-to-echo ratio for the front
center channel, front left and right channels. It may maintain a 1: 1 direct to echo ratio and a 2: 1
direct to echo ratio for the back left and right surround channels. As mentioned above, the direct
echo ratio for each channel is maintained by calculating a beam pattern having a directivity index
DI that compensates for changes in the distance r from the speaker array 4 to the listener 2.
[0046]
In one embodiment, the sound pressure P recognized by the listener 2 at a distance r from the
loudspeaker array 4 may be defined as follows.
[0047]
Here, Q is the sound power level (for example, volume) of the sound signal generated by the
directivity adjustment device 8 to drive the speaker array 4, T 60 is the reverberation time in the
room, V is the functional volume of the room, DI Indicates the directivity indicator of the sound
pattern emitted by the speaker array 4.
In one embodiment, when the distance r changes, the directivity adjustment device 8 adjusts the
sound power level Q of the beam pattern emitted by the speaker array 4 and / or the constant
sound pressure P by adjusting the directivity index DI. Maintain.
[0048]
As mentioned above, embodiments of the present invention provide machine-readable
instructions which instructions program one or more data processing components (collectively
referred to herein as a "processor") to perform the above-described operations. It may be a
product stored in a memory (e.g. a memory by microelectronics). In other embodiments, some of
these operations may be performed by specific hardware components including wired logic (eg,
dedicated digital filter blocks and state machines). Alternatively, such operations may be
performed by any combination of programmed data processing components and fixed wired
logic components.
[0049]
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16
While certain embodiments have been described and illustrated in the accompanying drawings, it
is to be understood that such embodiments are merely illustrative of the broad invention and are
not limiting, and the present invention is not limited thereto. It is not limited to the specific
configuration and arrangement shown and described. Because other various modifications may
occur to those skilled in the art. Accordingly, the description is considered to be illustrative
rather than restrictive.
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17
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