This overview discusses a patent that applies to audio system designed for brand spanking new immersive audio codecs in residence functions and Dolby Atmos, particularly. Not surprisingly, the patent was awarded to Dolby Laboratories Licensing Corp. Because the patent was granted, Voice Coil offered an in depth and informative overview – really helpful studying for anybody contemplating coming into this vital home-theater market section. This text was initially revealed in Voice Coil, February 2016.
Digital Peak Filter for Mirrored Sound Rendering Utilizing Upward Firing Drivers
Patent Quantity: US 9648440B2
Inventors: Brett G. Crockett (Brisbane, CA); Christophe Chabanne (Carpentras, France); Mark Tuffy (Sonoma, CA); Alan J. Seefeldt (San Francisco, CA); C. Phillip Brown (Castro Valley, CA); and Patrick Turnmire (Arroyo Seco, NM)
Assignee: Dolby Laboratories Licensing Corp. (San Francisco, CA)
Filed: January 7, 2014
US Class: 381/307
Granted: Could 9, 2017
Variety of Claims: 20
Variety of Drawings: 23
Summary from Patent
Embodiments are directed to audio system and circuits that mirror hold forth a ceiling to a listening location at a distance from a speaker. The mirrored sound offers peak cues to breed audio objects which have overhead audio elements. The speaker includes upward firing drivers to mirror hold forth of the higher floor and represents a digital peak speaker (proven in Determine 2 from the patent software). A digital peak filter primarily based on a directional listening to mannequin is utilized to the upward-firing driver sign to enhance the notion of peak for audio indicators transmitted by the digital peak speaker to offer optimum replica of the overhead mirrored sound. The digital peak filter could also be included as a part of a crossover circuit that separates the complete band and sends excessive frequency sound to the upward-firing driver.
Impartial Claims
43. A speaker driver for rendering sound for reflection off of an higher floor of a listening surroundings, comprising: a driver cone; a cone mud cap affixed to a central portion of the driving force cone; and a body securing the cone for mounting inside a speaker cupboard, whereby a minimum of one of many driver cone, mud cap, and body are configured to use a peak filter having a frequency response curve that’s configured to a minimum of partially take away directional cues from a speaker location, and a minimum of partially insert the directional cues from a mirrored speaker location, the frequency response curve primarily based on a primary frequency response of a filter modeling sound travelling straight from the mirrored speaker location to the listener’s ears at a listening place, for stated inserting of directional cues from the mirrored speaker location, and a second filter frequency response of a filter modeling sound touring straight from the speaker location to the listener’s ears on the listening place, for eradicating of directional cues for audio travelling alongside a path straight from the speaker location to the listener.
46. A system for rendering sound utilizing mirrored sound components, comprising: a speaker positioned at a speaker location and comprising a housing enclosing an upward-firing driver oriented at an inclination angle relative to the bottom aircraft and configured to mirror hold forth an higher floor of a listening surroundings to provide a mirrored speaker location; and a digital peak filter making use of a frequency response curve to an audio sign transmitted to the upward-firing driver, whereby the digital peak filter a minimum of partially removes directional cues from the speaker location and a minimum of partially inserts the directional cues from the mirrored speaker location, the frequency response curve primarily based on a primary frequency response of a filter modeling sound touring straight from the mirrored speaker location to the listener’s ears at a listening place, for stated inserting of directional cues from the mirrored speaker location, and a second filter frequency response of a filter modeling sound touring straight from the speaker location to the listener’s ears on the listening place, for eradicating of directional cues for audio travelling alongside a path straight from the speaker location to the listener.
59. A speaker for transmitting sound waves to be mirrored off an higher floor of a listening surroundings, comprising: a housing; an upward-firing driver throughout the housing and oriented at an inclination angle relative to a floor aircraft and configured to mirror hold forth a mirrored image level on the higher floor of the listening surroundings; and a digital peak filter making use of a frequency response curve to a sign transmitted to the upward-firing driver, the frequency response curve primarily based on a primary frequency response of a filter modeling sound travelling straight from a mirrored speaker location to the ears of a listener at a listening place, for inserting of directional cues from the mirrored speaker location, and a second filter frequency response of a filter modeling sound travelling straight from a speaker location to the ears of the listener on the listening place, for eradicating of directional cues for audio travelling alongside a path straight from a speaker location to the listener.
Reviewer Feedback
That is an up to date model of a Dolby international patent software “previewed” in Voice Coil final 12 months. We promised a overview when the US case grew to become accessible and right here it’s.
In 2012, Dolby launched its new, high-channel rely, ATMOS spatial rendering system into business theaters. The Dolby ATMOS Cinema Processor supported as much as 128 discrete audio tracks, utilizing greater than 60 loudspeakers in a business theater set up. The brand new stage directional management, making a hemispheric sound scape, is sort of spectacular, not solely in offering extra specificity inside a set of discrete picture angles throughout the 360° horizontal presentation, the system launched a brand new expertise of peak data and overhead imagery. Despite the fact that it was thought by many who it will not be sensible to translate this functionality into the home surroundings, rumors began nearly instantly that Dolby was making ready a home-theater model of the system with a extra sensible channel rely and system necessities—one that might render a convincing 360° horizontal/180° higher hemisphere presentation, emulating a scaled-down model of the business system to a considerable diploma.
The investigation into understanding the ear-brain system’s skill to localize vertical sound sources within the median aircraft goes again greater than 100 years. Earlier than that point, the prevailing thought was that two ears have been required to attain localization. Among the earliest research within the discipline was achieved by J. R. Angell and W. Fite, in 1901, of their Psychology Overview paper, “The Monaural Localization of Sound.” Their curiosity was piqued by a person who was deaf in a single ear, however was nonetheless capable of localize sound. They carried out a number of checks, evaluating the localization skill of a listener with regular listening to to that of the take a look at topic with just one correctly functioning ear. They concluded that variations in localizing skill, for advanced sounds in binaural and monaural (single ear) listening to, have been variations within the magnitude of the minimal threshold for locality, moderately than as absolute variations in localizing skill. Pure tones couldn’t be localized in monaural listening to, however advanced transient indicators have been localizable in each circumstances, albeit with superior angular acuity with binaural listening to.
Whereas there have been a couple of further research over the subsequent 65 years, the extra full understanding of the mechanisms concerned within the localization of vertical sources within the median aircraft and the position of the form of the exterior ear-pinna reflections, was superior by quite a few authors within the late Sixties and early Nineteen Seventies. Important contributions from E. A. G. Shaw in his two major papers, “Sound Strain Generated in an Exterior-Ear Duplicate and Actual Human Ears by a Close by Level Supply,” Journal of the Acoustical Society of America (JASA), Quantity 44, 1968 and “Transformation of Sound Strain Degree From the Free Discipline to the Eardrum within the horizontal Aircraft,” JASA, Quantity 56, 1974. These findings illustrated among the earliest confirmed knowledge that audio supply elevation within the median aircraft was usually represented by an elevated output at roughly 7 kHz and a null at 12 kHz (see Determine 3 from the appliance patent).
Earlier than this time, it was usually understood, that sinusoids and low-passed, advanced indicators, or noise, beneath 4 kHz will not be localizable as distinct vertical sound sources within the median aircraft. Analysis carried out within the mid-Nineteen Seventies, by an audio colleague of mine, Robert C. Williamson, discovered that that is solely true if the top is held motionless and the sonic stimuli is moved vertically whereas completely centered in entrance of the listening topic.
What he found was that our heads are continually making micro actions (much like a cat’s ears), scanning the audio area round our heads, like an infinite variety of microphones, for sounds which might be above and beneath the horizontal aircraft. Our ear-brain system invokes binaural sensing of vertical data by unconsciously tilting the top sideways and evaluating the timing of left/proper ear arrivals, permitting a lot larger precision in vertical picture location than high-frequency-based pinna reflections alone. (It was later discovered that others had already explored this situation, together with Mark F. Davis, now at Dolby Labs, in his commencement thesis at MIT, whereby he did research with headphones utilizing accelerometers and a pc to reposition the two-channel picture data relying on head actions.)
We additionally did experiments on the time that confirmed that one may notice extra discriminating vertical angle supply place detection, if the supply was elevated vertically whereas additionally being at roughly 45° of left, or proper, of heart, horizontally. This additionally allowed left/proper binaural scanning of the peak data, which was far more correct, and repeatable, than counting on solely the pinna transformations of the high-frequency response. Finally, every time a left/proper ear comparability can be utilized to “discover” a sound supply, together with vertical sources, the ear-brain system is extra able to pinpointing a sound supply location.
Binaural sensing is able to resolving angles of between 1° and 5°. Additionally, binaural listening to of picture placement is extra constant from listener to listener, whereas creating supply elevations by means of vertical, pinna high-frequency manipulations is far much less constant amongst listeners.
Associated papers that I keep in mind being notably stimulating throughout that interval, have been two that introduced among the first attention-grabbing propositions of making use of pinna responses to creating supply elevations, and realizing the character of misaligned loudspeakers, with inadvertent vertical spatialization, have been these of P. J. Bloom, “Creating Supply Elevations Illusions by Spectral Manipulation,” Journal of the Audio Engineering Society, September 1977 and, C. A. “Puddie” Rodgers, “Pinna Transformations and Sound Replica,” Journal of the Audio Engineering Society, April 1981. As usually occurs, Audio Engineering Society authors have been taking the data offered by the sooner pure analysis of the Acoustical Society of America authors and turning it into proposals for extra full understanding and manipulation of economic audio merchandise.
Within the early Nineteen Nineties, simply as Dolby Digital was changing into the brand new customary, Brian Aase, an engineer at Carver Corp., investigated the potential of making use of vertical processing to next-generation {surround} sound sign processors. Utilizing solely ahead radiating loudspeakers, Aase created a vertical spatialization mode primarily based on pinna transformation data from the analysis papers listed above. Not having a devoted “vertical channel” accessible, Aase developed a spatial detector, which might sense indicators that have been extremely decorrelated, and/or additionally had channel-trackable actions of a given sign, akin to a jet flyover that might begin at left-front and transfer to heart, then right-front and at last, into the right-rear-surround channel.
Though by no means commercialized, the system may very well be spectacular on sure program materials, but additionally it will inappropriately elevate guitars or drums that overly formidable recording engineers would pan throughout the channels, making a moderately sensational impact, however not a very correct one (though, I’m undecided what the recording engineers had in thoughts in consequence from that sort of recording approach within the first place). So, the system was restricted because of not having predictable, devoted, vertical channels accessible.
Quick-forward to 2012 and Dolby Labs comes on the scene with, “Atmos,” which includes devoted, height-information channels, considerably advancing the flexibility to appreciate nicely positioned, and purposeful, vertical and overhead soundscapes (see Determine 4B from the patent software). Primarily, the know-how can be utilized in a minimum of two modes—one the place one makes use of overhead mounted, in-ceiling, loudspeakers (principally a simplified model of the business theater methods) or, as coated within the present patent software, customary ground standing or stand mounted loudspeakers, with an extra, upward firing, peak data speaker, tailored to obtain the peak data channel.
The upward firing transducer, could be built-in into, or mounted on prime of, the loudspeakers akin to the usual horizontal data channels, such because the L/C/R, LS and RS, loudspeakers for five.1 (or extra with larger channel counts). The patent discloses circuits and loudspeakers which might be tailored to mirror hold forth a ceiling of a listening location in a listening room at a distance from a speaker. The sound mirrored off the ceiling floor is obtained on the listener, as peak cues, to breed audio “objects” which have overhead audio elements. The loudspeaker includes a minimum of one upward firing transducer to mirror hold forth the ceiling, representing a digital peak loudspeaker.
A digital peak filter, primarily based on a vertical, directional, pinna-based listening to mannequin, is utilized to the upward-firing transducer sign to reinforce the notion of peak for audio indicators transmitted by the digital peak loudspeaker, to optimize replica of the overhead mirrored sound. The digital peak filter could also be included as a part of a crossover circuit that separates the complete band and sends excessive frequency sound to the upward-firing driver or included within the processor offering the preprocessed enter sign to the loudspeaker energy amplifier channel. Room correction processes can be used to offer calibration and keep digital peak filtering in methods that carry out automated room equalization and different correction processes.
The loudspeakers and circuits are configured for use together with an adaptive audio enter sign and system for rendering spatialized sound utilizing mirrored sound components comprising an array of audio transducers for distribution round a listening surroundings, the place among the transducers are directed on the listener and others are upward-firing drivers that mission sound waves towards the ceiling of the listening surroundings for reflection to a particular listening space. What Dolby calls a “renderer” is used for processing audio streams and a number of metadata units which might be related to every audio stream, that specify a playback location within the listening surroundings of a respective audio stream, whereby the audio streams embrace a number of mirrored audio streams and a number of direct audio streams; and a playback system for rendering, and directing, the audio streams to the array of audio transducer with the a number of metadata units, and whereby the a number of mirrored audio streams are transmitted to the upward firing transducers.
Alternatively, the speaker methods can incorporate the specified pinna-based, frequency switch operate straight into the transducer design of the transducer configured to mirror hold forth the ceiling, so the specified frequency switch operate is likely to be included into the design of the transducer diaphragm, the diaphragm mud cap, affixed to a central portion of the transducer, or the body securing the cone.
The ceiling surfaces are going to differ considerably by way of reflection angle, diffusion, and absorption, such that the sonic arrival on the listener could differ relying on the surroundings. So, to complement the sound that’s mirrored off the ceiling to the listener, a secondary system is utilized. This secondary system, supplementary, peak data cue, could be delivered by the principle transducers within the left and proper entrance loudspeakers, with a direct sound path to the listener. The peak data that’s combined into the principle left and proper channel indicators is imbued with a frequency response modification that corresponds to the frequency response the ear would hear if receiving an acoustic sign from loudspeaker really mounted overhead.
There may be some hypothesis that the specs for the buyer model of the Atmos loudspeaker system will evolve over time to attain additional refinement. A few of these refinements could affect among the psychoacoustic questions concerning the system. For instance, if one has a mirrored sign arriving on the ears from the overhead ceiling reflection, then that sign upon arriving from the overhead angle, will obtain the frequency response modifications from the listeners outer ear, pinna transformation of the arrival sign. Then, why would you wish to have a pinna-based filter response within the arriving sign? Wouldn’t that “double course of” the arrival sign, offering much less compelling notion of peak? An alternate strategy is likely to be so as to add the pinna transformation to the direct sound sign and delayed by the trail size of the ceiling reflection, that means, it will possibly complement the overhead sign, in case the overhead sign is absorbed or not offering reference stage output on the listeners ears.
That stated, the system as it’s at the moment delivered, has offered satisfying overhead imaging when customers have sufficient reflective surfaces overhead, realizing larger 3-D imaging than what was beforehand accessible with the very best standard Dolby Encompass Sound methods. Kudos to Dolby for bringing a brand new customary to {the marketplace}, which is beginning to notice the potential of an idea whose time has lastly come. VC
This text was initially revealed in Voice Coil, February 2016.
