US 7894611

Patent Overview — US 7,894,611 B2

Title: Spatial disassembly processor
Assignee: Bose Corporation (original assignee Bose Corp)
Inventors: Paul E. Beckmann; Finn A. Arnold
Priority date: 1994-04-15
Filing date: 2009-12-07 (application US12/631,911)
Publication: US20100086136A1 (2010-04-08); granted 2011-02-22
Status as listed: Expired – Fee Related; anticipated expiration 2014-04-15
Classification: H04S7/00, H04S7/30 (control circuits for electronic adaptation of the sound field)

Purpose: The invention "relates to a method and apparatus for spatially disassembling signals, such as stereo audio signals, to produce additional signal channels." Spatial disassembly separates the information in the two channels of a stereo signal to produce additional channels while preserving the original spatial distribution. The patent distinguishes prior linear (dematrixing) and steered approaches, noting the latter operate "on audio at a macroscopic level" and require temporal separation. The stated distinguishing characteristic is that input channels "are split into a multitude of frequency components, and steering occurs on a frequency by frequency basis."

Plain-language scope: A pair of input signals L(t) and R(t) is decomposed into subband representations (e.g., via a short-term Fourier transform) and processed to form N output channel signals o1(t)…oN(t). A construction rule fj,k(·) is defined so that, when reproduced over N spatially separated loudspeakers, a perceived loudness and perceived location of the kth subband match those of the input signals reproduced over a pair of speakers. In the described embodiment, a 2-to-3 channel processor yields left, center, and right outputs using overlapping windowed blocks (P = 2048 samples, half-block overlap), zero padding, FFT to 4096 coefficients, spatial disassembly processing, inverse FFT, windowing, and overlap-add. Spectral and spatial balance constraints are given, with a blend factor α that is frequency dependent (no processing below 250 Hz; constant B above 1 kHz).

What the excerpt does not establish: It provides only a partial text; the claims, complete equations, detailed processing rules, and the full specification are omitted. Legal status is stated as an assumption, not a legal conclusion. No litigation, ownership transfer, validity, or prior-art analysis is included or implied.

Source: https://patents.google.com/patent/US7894611/en