# US 9,883,318 B2 · System and method for stereo field enhancement in two-channel audio systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,883,318 B2 - Document ID: US9883318B2 - Status: Granted - Kind: B2 - Application number: 15/213,741 - Filed: 2016-07-19 - Published: 2017-02-09 - Granted: 2018-01-30 - Earliest claimed: 2013-06-12 - Assignees: Bongiovi Acoustics LLC - Applicants: Bongiovi Acoustics LLC - Inventors: Anthony Bongiovi; Glenn Zelniker; Joseph G. Butera - Web page: https://patentgrep.com/patent/US9883318B2 ## CPC - H04S 7/307: {Frequency adjustment, e.g. tone control (H04S7/301 takes precedence)} - H04S 1/007: {in which the audio signals are in digital form (data reduction aspects thereof based on psychoacoustics G10L19/02)} - H04S 2400/05: Generation or adaptation of centre channel in multi-channel audio systems - H04S 2400/13: Aspects of volume control, not necessarily automatic, in stereophonic sound systems - H04S 2420/07: Synergistic effects of band splitting and sub-band processing - H04S: STEREOPHONIC SYSTEMS ## Abstract The present invention provides methods and systems for digitally processing audio signals in two-channel audio systems and/or applications. In particular, the present invention includes a first filter structured to split a two-channel audio input signal into a low frequency signal and a higher frequency signal. A M/S splitter is then structured to split the higher frequency signal into a middle and a side signal. A detection module is then configured to create a detection signal from the middle signal, which is used in a compression module configured to modulate the side signal to create a gain-modulated side signal. A processing module is then structured to combine the low frequency signal, middle signal, and the gain-modulated side signal to form a final output signal. ## Claims ### Claim 1 A method for stereo field enhancement in two-channel audio systems, comprising: splitting a two-channel audio input signal into a low frequency signal and a higher frequency signal using a first cutoff frequency, splitting the higher frequency signal into a middle signal and a side signal, processing the middle signal using a detection module to create a detection signal, dynamically adjusting the gain on the side signal using the detection signal to create a gain-modulated side signal, and adjusting the gain-modulated side signal to a point at least equal to the side signal. ### Claim 2 (depends on 1) The method as recited in claim 1 further comprising combining the low frequency signal, the middle signal, and the gain-modulated side signal to form a final output signal. ### Claim 3 (depends on 1) The method as recited in claim 1 further comprising combining the middle signal and the gain-modulated side signal to form a processed higher frequency signal. ### Claim 4 (depends on 3) The method as recited in claim 3 further comprising splitting the processed higher frequency signal into a high frequency signal and a midrange frequency signal using a second cutoff frequency. ### Claim 5 (depends on 4) The method as recited in claim 4 further comprising delaying the high frequency signal using a delay module to create a delayed high frequency signal. ### Claim 6 (depends on 5) The method as recited in claim 5 further comprising combining the low frequency signal, the midrange frequency signal, and the delayed high frequency signal to form a final output signal. ### Claim 7 (depends on 4) The method as recited in claim 4 wherein the second cutoff frequency is selected from the range between 1 kHz and 20 kHz. ### Claim 8 (depends on 5) The method as recited in claim 5 wherein the delay module delays the high frequency signal with a delay interval selected from the range between 1 and 999 samples. ### Claim 9 (depends on 1) The method as recited in claim 1 wherein the first cutoff frequency is selected from the range between 20 Hz and 1000 Hz. ### Claim 10 (depends on 1) The method as recited in claim 1 defining the two-channel audio input signal to comprise a right channel signal and a left channel signal. ### Claim 11 (depends on 10) The method as recited in claim 10 defining the middle signal to comprise the sum of the right channel signal and the left channel signal. ### Claim 12 (depends on 10) The method as recited in claim 10 defining the side signal to comprise the sum of the right channel signal and the inverse of the left channel signal. ### Claim 13 (depends on 1) The method as recited in claim 1 wherein the detection module comprises at least two shelving filters structured to create a 24 dB differential between high and low frequencies in the middle signal. ### Claim 14 (depends on 1) The method as recited in claim 1 wherein the step of adjusting the gain on the side signal further comprises adjusting the gain using a compression module limited to an adjustable gain reduction ceiling. ### Claim 15 (depends on 14) The method as recited in claim 14 wherein the compression module comprises an adjustable gain reduction ceiling selected from the range between 0 dB and 12 dB. ### Claim 16 (depends on 14) The method as recited in claim 14 wherein the compression module comprises an adjustable gain reduction ceiling corresponding to the makeup gain. ### Claim 17 A system for stereo field enhancement in two-channel audio systems, comprising: a two-channel audio input signal, a first filter structured to split said two-channel audio input signal into at least a low frequency signal and a higher frequency signal based on a first cutoff frequency, a splitter structured to split said higher frequency signal into a middle signal and a side signal, a detection module configured to create a detection signal from said middle signal, a compression module configured to modulate said side signal based on said detection signal in order to create a gain-modulated side signal, and a processing module configured to combine said low frequency signal, middle signal, and said gain-modulated side signal to form a final output signal. ### Claim 18 (depends on 17) The system as recited in claim 17 wherein said first filter is further structured with a first cutoff frequency selected from the range between 20 Hz and 1000 Hz. ### Claim 19 (depends on 17) The system as recited in claim 17 wherein said two-channel audio input signal comprises a right channel signal and a left channel signal. ### Claim 20 (depends on 17) The system as recited in claim 17 wherein said detection module comprises at least two shelving filters. ### Claim 21 (depends on 17) The system as recited in claim 17 wherein said compression module is further configured with an adjustable gain reduction ceiling selected from the range between 0 dB and 12 dB. ### Claim 22 (depends on 17) The system as recited in claim 17 wherein said processing module is further configured to adjust said gain-modulated side signal with a makeup gain. ### Claim 23 (depends on 22) The system as recited in claim 22 wherein said compression module is further configured with an adjustable gain reduction ceiling corresponding to said makeup gain of said processing module. ### Claim 24 A system for stereo field enhancement in multi-channel audio systems, comprising: an audio input signal, a first filter structured to split said audio input signal into a low frequency signal and a higher frequency signal based on a first cutoff frequency, a M/S splitter structured to split said higher frequency signal into a middle signal and a side signal, a detection module configured to create a detection signal from said middle signal, a compression module configured to dynamically modulate said side signal based on said detection signal in order to create a gain-modulated side signal, a processing module configured to combine said middle signal and said gain-modulated side signal to form a processed higher frequency signal, a second filter structured to split the processed higher frequency signal into a high frequency signal and a midrange frequency signal using a second cutoff frequency, and a combination module structured to combine said low frequency signal, said midrange frequency signal, and said high frequency signal to form a final output signal. ### Claim 25 (depends on 24) The system as recited in claim 24 wherein said first cutoff frequency is selected from the range between 20 Hz and 1000 Hz. ### Claim 26 (depends on 24) The system as recited in claim 24 wherein said second cutoff is selected from the range between 1 kHz and 20 kHz. ### Claim 27 (depends on 24) The system as recited in claim 24 further comprising a delay module configured to delay said high frequency signal with a delay interval selected from the range between 1 and 999 samples. ### Claim 28 (depends on 24) The system as recited in claim 24 wherein said compression module is further configured with an adjustable gain reduction ceiling selected from the range between 0 dB and 12 dB.