Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers, loudspeakers or microphones
  • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R29/00—Monitoring arrangements; Testing arrangements
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2217/00—Details of magnetostrictive, piezoelectric, or electrostrictive transducers covered by H04R15/00 or H04R17/00 but not provided for in any of their subgroups
  • H04R2217/03—Parametric transducers where sound is generated or captured by the acoustic demodulation of amplitude modulated ultrasonic waves

Definitions

• Non-linear transduction results from the introduction of sufficiently intense, audio- modulated ultrasonic signals into an air column.
• Self-demodulation, or down-conversion occurs along the air column resulting in the production of an audible acoustic signal.
• This process occurs because of the known physical principle that when two sound waves with different frequencies are radiated simultaneously in the same medium, a modulated waveform including the sum and difference of the two frequencies is produced by the non-linear (parametric) interaction of the two sound waves.
• the two original sound waves are ultrasonic waves and the difference between them is selected to be an audio frequency, audible sound can be generated by the parametric interaction.
• FIG. 15 is a diagram illustrating an example of harmonic distortion error correction utilizing the original audio input as an input to the recursion process in accordance with one embodiment of the technology described herein.
• FIG. 16 is a diagram illustrating an example of recursive processing using the original audio input (i.e., non feed-forward) in accordance with one embodiment of the technology described herein.
• Distortion can be thought of as a signal or sound on the output that differs from what is desired.
• Nonlinear distortion involves creating tones or frequencies that were not in the input.
• Many ultrasonic audio delivery systems already exploit nonlinear distortion to create audio from ultrasound. As a result, these systems may be susceptible to unwanted nonlinear distortion.
• Various embodiments of the technology disclosed herein can be implemented to work to compensate for this distortion by modifying the input audio so that when it is ultimately demodulated in the air, the original input is reproduced as faithfully as practical or possible.
• FIG. 1 is a diagram illustrating an ultrasonic sound system suitable for use in conjunction with the systems and methods described herein.
• audio content from an audio source 2, such as, for example, a microphone, memory, a data storage device, streaming media source, MP3, CD, DVD, set-top-box, or other audio source is received.
• the audio content may be decoded and converted from digital to analog form, depending on the source.
• the audio content received by the ultrasonic audio system 1 is modulated onto an ultrasonic carrier of frequency fl, using a modulator.
• the modulator typically includes a local oscillator 3 to generate the ultrasonic carrier signal, and modulator 4 to modulate the audio signal on the carrier signal.
• FIG. 1 is optimized for use in processing two input and output channels (e.g., a "stereo" signal), with various components or circuits including substantially matching components for each channel of the signal. It will be understood by one of ordinary skill in the art after reading this description that the audio system can be
• FIG. 6 is a diagram illustrating an example application of equation 4. As can be seen, the application of equation 4 provides a dramatic reduction to the distortion products as shown by the dashed lines. Not only does it greatly reduce the first-order (doubles and sums) but those resulting corrections reduce higher order products as well.
• Phase+EQ module 329 Phase+EQ module 329, a summing module 331 and a Scaling module 333.
• the first block in this example Intermodulation Error Correction Module 322 is an IMError module 325, which generates an estimate of the error due to intermodulation distortion. This can be referred to as an error signal or error function.
• This estimated error signal 326 is inverted by inversion module 327 to create an inverted estimated error signal 328.
• inversion module 327 is configured to transform the estimated error signal 326 to the additive inverse of the estimated error signal. This effectively changes the sign of estimated error signal 326. This may be accomplished, for example by multiplying the error signal by negative one (e.g., *-l) to change its sign.
• each error correction module 322, 370 can be implemented using, for example, the modules shown in FIGs. 8 and 9, respectively.
• FIG. 11 is a diagram illustrating an example block for basic intermodulation error correction in accordance with one embodiment of the technology described herein.
• Intermodulation Error Correction Module 720 operates similarly to Intermodulation Error Correction Module 322 as shown above in FIG. 8, but is illustrated as having two
• FIGs. 17, 18 and 19 are the feed-forward block diagrams illustrating examples of both harmonic and intermodulation error correction.
• FIG. 17 is a diagram illustrating an example intermodulation error correction with feedforward processing in accordance with one embodiment of the technology described herein.
• this example includes two Phase+EQ modules 841, 853, an IM error correction module 843, two summing modules 845, 847, two inversion modules 849, 851 and a scaling module 854.
• Inversion modules 849, 851 can be implemented to generate the additive inverse of their respective input signals (e.g., perform a *-l operation).
• Phase+EQ modules 841, 853, IM error correction module 843, summing module 847, inversion module 851 and scaling module 854 can be implemented using the same features and functionality as described above for the corresponding blocks in FIG. 14.
• Phase+EQ module 871 or 881 can be omitted or configured to not make any adjustments to the signal.
• Phase+EQ modules 871, 881, HError estimation module 873, summing module 883 and scaling module 884 can be implemented using the same features and functionality as described above for the corresponding modules in FIG. 15.
• FIG. 19 is a diagram illustrating an example of feed-forward, recursive processing in accordance with another embodiment of the systems and methods disclosed herein.
• This example shows multiple rounds of feed-forward error correction for both intermodulation error correction and harmonic distortion error correction.
• This also illustrates an example in which the error signals from a given round (the feed-forward error signals) can be fed forward and used in the next round of correction.
• the order of error correction can be reversed.
• each round may have different values for Phase+EQ and Scaling, which may be all set sequentially via empirical measurement.
• the computing module 900 might also include one or more various forms of information storage mechanism 910, which might include, for example, a media drive 912 and a storage unit interface 920.
• the media drive 912 might include a drive or other mechanism to support fixed or removable storage media 914.
• a hard disk drive, a floppy disk drive, a magnetic tape drive, an optical disk drive, a CD or DVD drive (R or RW), or other removable or fixed media drive might be provided.
• storage media 914 might include, for example, a hard disk, a floppy disk, magnetic tape, cartridge, optical disk, a CD or DVD, or other fixed or removable medium that is read by, written to or accessed by media drive 912.
• the various diagrams may depict an example architectural or other configuration for the disclosed technology, which is done to aid in understanding the features and functionality that can be included in the disclosed technology.
• the disclosed technology is not restricted to the illustrated example architectures or configurations, but the desired features can be implemented using a variety of alternative architectures and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical partitioning and configurations can be implemented to implement the desired features of the technology disclosed herein. Also, a multitude of different constituent module names other than those depicted herein can be applied to the various partitions.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Otolaryngology (AREA)
• Circuit For Audible Band Transducer (AREA)
• Transducers For Ultrasonic Waves (AREA)

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• 2014
  • 2014-12-10 US US14/566,592 patent/US9432785B2/en active Active
• 2015
  • 2015-11-23 EP EP15805371.0A patent/EP3231192B1/en active Active
  • 2015-11-23 ES ES15805371.0T patent/ES2690749T3/es active Active
  • 2015-11-23 WO PCT/US2015/062207 patent/WO2016094075A1/en not_active Ceased
  • 2015-11-23 CN CN201580075695.2A patent/CN107211209B/zh active Active
  • 2015-11-23 JP JP2017531308A patent/JP6559237B2/ja active Active

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