Tech Briefs Magazine - October 2021 - 6a

SIMULATION-BASED PRODUCT DEVELOPMENT
FIGURE 4         
12.7 centimeters, thick.) In general,
it sounded pretty immersive, but we
wanted to make the design more
competitive. " After more market
research, Tipparaju and his team opted
to develop a DAES that was 1 inch
thick. To meet the ultrathin design
constraints, they incorporated an
ultrathin microtransducer (90 millimeters
by 15 millimeters) into the design of
the speaker. In addition, they added
an acoustic reflector into the speaker's
design to efficiently redistribute acoustic
energy toward the ceiling - ultimately
improving the speaker's sweet spot
coverage area in the process.
With acoustic finite element method
(FEM) and boundary element method
(BEM) functionality in the software,
Tipparaju optimized the acoustic reflector
topology to create an asymmetric
radiation pattern to maximize the energy
distribution along the ceiling direction
(0 degrees to +90 degrees) and to
sufficiently attenuate the direct sound (0
degrees to -90 degrees) to the listener, as
shown in Figure 2.
An FEM study was performed to
optimize the acoustic reflector topology
based on the vertical plane directivity
in free-field, while a BEM analysis
was used to numerically assess the
directional response benefits of the
acoustic reflector, considering TV panel
integration constraints and ceiling
reflections. " We want to ensure that
there is uniform height channel coverage
around a listener's position, " said
Tipparaju. Being able to evaluate sound
6a COMSOL NEWS
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pressure distribution along a ceiling in
simulations is very valuable, as it helps
to determine the optimal left and right
speaker module spacing and transducer
architecture, according to Tipparaju.
In their simulations, Dolby
Laboratories often takes into account
the different ceiling height boundary
conditions. " In the United States, the
typical ceiling height is about 8 to 12
feet high, and we do evaluate the
speaker response at those different
conditions, " said Tipparaju.
» VALIDATING THE RESULTS
WITH A NEAR-FIELD SCANNER
Based on the simulation results, physical
prototypes of the slim height channel
speaker with an integrated acoustic
reflector were built for testing and
validation.
The free-field sound pressure results
of the FEM study were validated with
experimental results from a Klippel NearField
Scanner (NFS) measurement system.
" The benefit of using a near-field scanner
is that we can take fast 3D anechoic
acoustic measurements in any given space
or any given room, " said Tipparaju.
Overall, Dolby Laboratories was able
to determine that an integrated acoustic
reflector can significantly improve the
immersiveness of slim height channel
speakers. In order to further enhance the
premium, immersive audio experience
for TVs, Dolby Laboratories is currently
working on extending the acoustic
reflector technology for side-firing
surround TV speakers.
FIGURE 5   
  
    
    
» THE FUTURE OF IMMERSIVE
AUDIO TECHNOLOGY
" Our team's main goal is to develop
different acoustic hardware systems and
technologies, so that we can increase
Dolby Atmos®
adoption in different
consumer electronic products, " said
Tipparaju. In the future, Dolby plans to
develop Dolby Atmos®
enabled speaker
technology for the smart speaker and
wireless speaker market.
According to Tipparaju, this will be
an interesting venture, because he will
need to work closely with more compact
form factors that contain microphone
arrays and additional speakers. With the
help of simulation, he plans to develop
hardware solutions to improve the
immersiveness in this type of system.
ACKNOWLEDGEMENT
Lakshmikanth Tipparaju would like
to thank his manager John Stewart,
his colleagues within the Enhanced
Consumer Devices Innovation team, and
Atmos TV product management within
Dolby for supporting this work.
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 
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Tech Briefs Magazine - October 2021

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