REVIEWS OF ACOUSTICAL PATENTS

• JAMES DEGRANDIS, Acoustics First Corp., 2247 Tomlin Street, Richmond, Virginia 23230

• MARK KAHRS, Pittsburgh, Pennsylvania

• ERIC E. UNGAR, Acentech, Incorporated, 33 Moulton Street, Cambridge, Massachusetts 02138

Vincenzo Zaccá et al., assignors to Bang & Olufsen A/S

14 February 2023; filed 16 October 2020

As far back as 1998 (and earlier) Craven and Gerzon proposed (US Patent 6,760,451) using a test signal to compensate loudspeakers. The invention of inexpensive microphones (first elecrets, now micro-electromechanical systems, MEMS) has made it possible to cheaply embed microphones with every loudspeaker. These sensors can be used to estimate the room acoustics and create room-specific compensation filters. For example, US Patent 8,577,048 (filed by Harman in 2006) describes such a system but does not describe algorithms. Bang and Olufsen have been interested in this since at least 2002 (see US Patent Application 20,154,785). This patent is specific and details an optimization algorithm for solving a linear system of equations. This is a well-known problem and use of the Lasso method can easily be found. The inventor claims that Lasso works well except when the loudspeaker is in a corner and provides for a compensation method. —MK

Kenji Yamada and Yasuyuki Watanabe, assignors to Roland Corporation

14 February 2023; filed 25 August 2020

Another in a very long line of patents that describe the minute details of a chord-based sequencer. In this case, arpeggiated chords are generated from the root. As a bonus, the patent goes into great detail about how to generate notes with different tempo markings. —MK

Jorma Mäkinen et al., assignors to NOKIA TECHNOLOGIES OY

14 February 2023; filed 25 June 2020

Although specifically for speech recognition, this could equally apply to noise reduction for an outdoor multi-microphone array. The inventors straight-forwardly propose using a filter bank (and give the Short Time Fourier Transform (STFT) or Quadrature Mirror Filters (QMF) as possible solutions). The output is analyzed for wind noise and handling noise. —MK

Elias Kokkinis and Alexandros Tsilfidis, assignors to Meta Platforms Technologies, LLC

14 February 2023; filed 28 January 2022

Non-negative matrix factorization (NMF) appeared on the scene not quite 20 years ago. Since then, it has made significant inroads in source separation, among other applications. In this application, NMF is augmented with the introduction of a training sequence, as shown in the figure. This is mentioned specifically as a means to separate the direct signal source from interfering sources. —MK

Emery M. Ku et al., assignors to BOSE CORPORATION

21 February 2023; filed 25 August 2021

The microphone/loudspeaker feedback/feedforward loop has been known for decades (It also goes by the names “squealing” and “howling”). This takes on added importance in hearing aids (now known as “hearables”) where the microphone is located close to the output transducer. Here, the inventors from Bose propose using zero crossing as part of an oscillation detection algorithm. Interested readers may also want to examine US Patent No. 9,792,893 in which another team from Bose lays out their noise-canceling algorithm. There are many patents devoted to feedback cancellation including a very early one by Bose himself (US Patent No. 4,494,074). —MK

Erich Tisch et al., assignors to GoPro, Inc.

21 February 2023; filed 30 April 2021

Suppose you design a multi-microphone camera system to operate outdoors: How would you choose the appropriate microphone for a recording if being soaked by water is a possibility? The inventors from Go-Pro propose using a frequency subband algorithm to determine which microphones are usable. The figure shows how subbands can be correlated for decision making. —MK

Peter McCutcheon et al., assignors to AMS SENSORS UK LIMITED

28 February 2023; filed 18 September 2019

The title is obtuse and actually refers to the tuning of a feedback control system in a hearing aid. The patent considers the full transfer function including the eardrum. The figure shows the calibration (tuning) methodology explored in the patent. —MK

Indrani Chattopadhyay et al., assignors to Shankar, Mukherjee

7 March 2023; filed 5 August 2019

The inventors propose using Indian Ragas to treat patients with Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder. This dynamic system adjusts note volume and rhythm patterns according to external observation (including EEG). However, will this work for patients who do not reside in the Indian subcontinent? This and other questions remain unanswered in this disclosure. —MK

Yoshihiko Tamaru et al., assignors to Sony Interactive Entertainment Inc.

7 March 2023; filed 23 August 2018

Once again, imagine a loudspeaker and a microphone. Since there could be a distance between them, there will be a time delay and possibly reverberation. Suppose that the sampling rates are not identical. Then surely one must be converted to the other if processing will be done at that rate. That is the patent. Assuredly, when the patent was filed in 2018, matching sampling rates were well known to those “skilled in the art.” The figure shows algorithms for noise reduction, echo removal, and the like, but these are not discussed in the patent. —MK

Jason Gillette and Kuan-Wen Chiu, assignors to Turf Design, Inc.

14 March 2023; filed 17 February 2020

This patent has two primary inventions. The first is a system of designing baffles from flat sheets of felt that can be folded into more substantial objects using simple clips to maintain their shape. The second is a method for securing these devices into a baffle mounting system using specialized notches and hardware. Acoustic felt made from polyethylene terephthalate (PET) is one of the many materials created from the push to recycle. Created from recycled bottles, this material has many benefits but is somewhat rare to find in greater thicknesses as it is produced in sheets, not blocks. This patent proposes a method of creating those thicker elements by scoring, beveling, and folding the sheets into more robust shapes—not unlike making a box from a flat sheet using origami. Further, this design allows for the baffles to be shipped flat, folded in the field, and assembled using special clips. Creating more functional baffles from flat PET felt sheets with clips that secure the form, and cutting notches to mount the baffle, are the two novel elements in this patent. Various embodiments of those two elements are presented; different baffle shapes are proposed, as are grid designs for using the baffles to create arrays. —JD

Juergen Sauer and Veronika Wagner, assignors to APPLE INC.

14 March 2023; filed 6 July 2021

The compressibility of the air in the back-volume of a loudspeaker arrangement, such as one in a compact device, and the associated wave motions may act on the loudspeaker's membrane and distort the sound that is intended to be radiated by the membrane. This effect is reduced by coating some of the walls of the back-volume with absorptive material. The patent suggests suitable coating materials. —EEU

Albert Bach-Esteve Burch et al., assignors to SOLER & PALAU RESEARCH, S.L.

28 March 2023; filed 27 May 2020

The attached figure is a schematic sidewise section of the patent component arrangement, which is intended to reduce noise-radiating vibrations in a fan or similar flow-generating apparatus induced by the motor's rotor/station AC interaction. In essence, the motor A and fan are supported rigidly on a grillage-like housing 2. This housing is supported from outer housing 1 via resilient elements 5. —EEU

Alan T. Snyder

28 March 2023; filed 4 March 2022

This patent pertains to rhythmic percussive instruments that are shaken or struck by hand. The designs described here are devised to enable the generation of various sounds, depending on how severely and in what direction the instrument is shaken. The attached figure is a partial sectional view of one illustrative embodiment. Hollow chambers 350 and 354 are separated from each other by an elastomeric plug 360. Chamber 354 is closed off by an elastomeric plug 362 and contains small plastic beads 372 and a ball-bearing-type ball 370. A striker set 320 with a rod 312 may include a spring coil 340. —EEU

Jianguang Wen et al., assignors to SUZHOU SENSORFUN ELECTRONICS CO., LTD

28 March 2023; filed 12 September 2019

This patent describes a compact acoustic receiver such as may be used in a handset. The described receiver design details are claimed to facilitate manufacture and to provide cost savings. —EEU

Renate Eva Klementine Landig et al., assignors to Meta Platforms Technologies, LLC

4 April 2023; filed 23 December 2019

This patent deals with configurations employing dielectric polymers with nano-scale voids to induce or actively attenuate vibrations, particularly in items with small physical dimensions. —EEU

Peter M. Eick and Joel D. Brewer, assignors to ConocoPhillips Company

4 April 2023; filed 2 April 2020

This patent deals with methods for designing seismic surveys and acquisition of seismic data with reduced noise. Equally or optimally irregularly spaced sources or receivers are spaced on the basis of prime number ratios. —EEU