In 2014, Dolby Laboratories launched Dolby Atmos® enabled speaker (DAES) expertise for dwelling theater programs and later expanded this expertise for soundbar merchandise. Now they’re growing DAES expertise for TVs to push the boundaries of what’s potential for immersive dwelling audio expertise.
The Science of Dolby Atmos® Enabled Audio system
To breed life like overhead sound, DAES expertise employs an upward-firing speaker design to radiate sound upward to replicate off the ceiling, as proven in Determine 1. Perceptual filtering is utilized to those audio system to amplify their sense of elevation, permitting shoppers to understand the placement of sound origination as the purpose of reflection within the ceiling and never the bodily speaker location. “When you have conventional TV audio system, you’ll hear the speaker’s sound emitting proper in entrance of you from the TV. With Dolby Atmos® enabled TV audio system, you’ll hear overhead sound coming from the ceiling,” mentioned Lakshmikanth Tipparaju, a senior acoustic system and transducer engineer at Dolby Laboratories.
Determine 1. A sketch of a standard (giant type issue) peak channel speaker.
Design Challenges for Ultrathin TV Audio system
Slim type issue TV design constraints make it tough to design DAES for TVs. As TV designs are made extra compact, the form and space obtainable for the upward-firing speaker diaphragm, which is carefully coupled to a boundary floor, turns into extra restricted by the thickness of the TV, leading to a slender peak channel ceiling picture.
Designing slim Dolby Atmos® enabled TV audio system which can be in a position to present giant candy spot protection across the typical place of a listener is a key problem, in keeping with Tipparaju. “A candy spot protection space is the area the place we are able to persistently understand peak channel picture on the ceiling. The ceiling picture is compromised once we transfer away from the candy spot protection space,” mentioned Tipparaju.
With a purpose to design a DAES that’s each skinny sufficient to be constructed into fashionable televisions and gives giant candy spot protection, Dolby Laboratories turned to acoustics simulation. Tipparaju believes a key good thing about simulation expertise is that it permits him to guage the efficiency of recent speaker designs previous to constructing and testing an precise bodily prototype — saving helpful time and sources.
Acoustical FEM and BEM Analyses
Utilizing acoustics modeling within the COMSOL Multiphysics® simulation software program, Tipparaju explored a number of totally different upward-firing speaker design ideas for optimizing the candy spot protection. To fulfill the ultrathin design constraints, they included an ultrathin microtransducer (90 millimeters by 15 millimeters) into the design of the speaker. As well as, they added an acoustic reflector into the speaker’s design to effectively redistribute acoustic power towards the ceiling — finally enhancing the speaker’s candy spot protection space within the course of.
Determine 2. Slim peak speaker with built-in acoustic reflector — directivity analysis airplane.
With acoustic finite factor methodology (FEM) and boundary factor methodology (BEM) performance within the Acoustics Module, an add-on to COMSOL Multiphysics®, Tipparaju optimized the acoustic reflector topology to create an uneven radiation sample to maximise the power distribution alongside the ceiling route (0 levels to +90 levels) and to sufficiently attenuate the direct sound (0 diploma to -90 levels) to the listener, as proven in Determine 2.
Determine 3. Simulated vertical airplane directivity comparability of a slim peak speaker with an built-in reflector (prime) and a standard slim peak speaker with no reflector (backside). Right here, it’s proven that the speaker with the reflector has a wider protection for ceiling reflection.
An FEM research was carried out to optimize the acoustic reflector topology primarily based on the vertical airplane directivity in free-field, whereas a BEM evaluation was used to numerically assess the directional response advantages of the acoustic reflector, contemplating TV panel integration constraints and ceiling reflections. “We wish to guarantee that there’s uniform peak channel protection round a listener’s place,” mentioned Tipparaju. Having the ability to consider sound strain distribution alongside a ceiling in simulations may be very helpful, because it helps to find out the optimum left and proper speaker module spacing and transducer structure, in keeping with Tipparaju.
Determine 4. A multislice plot depicting SPL distribution at 10 kHz in COMSOL Multiphysics®.
Validating the Outcomes with a Close to-Subject Scanner
Based mostly on the simulation outcomes, bodily prototypes of the slim peak channel speaker with an built-in acoustic reflector had been constructed for testing and validation. The free-field sound strain outcomes of the FEM research had been validated with experimental outcomes from a Klippel Close to-Subject Scanner (NFS) measurement system. Total, Dolby Laboratories was in a position to decide that an built-in acoustic reflector can considerably enhance the immersiveness of slim peak channel audio system.
Determine 5. Prototype of the ultrathin microtransducer (left) and an ultrathin DAES with a 1 inch thickness (proper).
Sooner or later, Dolby plans to develop Dolby Atmos® enabled speaker expertise for the good speaker and wi-fi speaker market.
Acknowledgement
Lakshmikanth Tipparaju wish to thank his supervisor John Stewart, his colleagues inside the Enhanced Client Gadgets Innovation group, and Atmos TV product administration inside Dolby for supporting this work.
Dolby Atmos is a registered trademark of Dolby Laboratories Licensing Company.