How to Automatically Generate Musical Harmonies from Audio
This 2012 patent describes a system that listens to music and automatically generates harmony notes to accompany a melody, even detecting and ignoring accidental strums on stringed instruments.
Original patent title: “Musical harmony generation from polyphonic audio signals”
This 2012 patent describes a system that listens to music and automatically generates harmony notes to accompany a melody, even detecting and ignoring accidental strums on stringed instruments. Granted to Harman International Industries Canada Ltd in 2012 with 78 claims and 24 forward citations, and it is expected to expire in 2027.
Coverage
What does this patent actually cover?
This patent details an apparatus that can create musical harmonies. It takes a melody signal and an accompaniment signal, analyzes their sound content, and then figures out what harmony notes would sound good. Specifically, it identifies the current melody note and looks at the 'spectral content' (basically, the mix of frequencies) of the accompaniment music. Using this information, it generates at least one harmony note. A clever part is its ability to detect and ignore 'unintentional strums' from stringed instruments, like when a guitarist accidentally brushes strings during a chord change, so it doesn't mess up the generated harmony. It can even output these harmonies as MIDI data or mix them with the original sounds for real-time performance.
The gap
What does this patent NOT cover?
- Generating harmonies without analyzing the spectral content of an accompaniment signal
- Generating harmonies without identifying a current melody note
- Harmony generation that does not suppress determination based on an unintentional strum
- Methods that do not involve receiving at least one polyphonic electrical signal from a multi-stringed instrument
- Detecting unintentional strums without comparing received notes to templates based on open string tuning
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The innovation lies in the system's ability to not only generate harmonies but also to intelligently filter out unwanted musical 'noise,' specifically unintentional strums on stringed instruments, ensuring the generated harmony remains musically coherent.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Music production software (DAWs) with auto-harmony features
Digital audio workstations (DAWs)
Live performance accompaniment systems
Virtual instrument plugins
Why it matters
The bigger picture
This patent addresses a core challenge in music production: creating convincing instrumental accompaniments and harmonies automatically. It provides a technical solution for software and hardware that can assist musicians, from hobbyists to professionals, in arranging and performing music by intelligently adding harmonic layers.
Filed
October 2, 2007
Granted
May 1, 2012
Market context
Who's building on this
Companies in this space
Companies involved in digital audio workstations (DAWs) and music creation software, such as Avid (Pro Tools), Steinberg (Cubase), and Ableton, likely incorporate similar technologies. Virtual instrument developers and manufacturers of audio hardware with built-in musical effects also operate in this space.
Market impact
This patent's technology enables more sophisticated and automated music creation tools. It has contributed to the development of software that can assist musicians in generating complex arrangements, making music production more accessible and efficient for a wider range of users.
Claim 1 — Plain English
What this patent covers
This patent details an apparatus that can create musical harmonies. It takes a melody signal and an accompaniment signal, analyzes their sound content, and then figures out what harmony notes would sound good. Specifically, it identifies the current melody note and looks at the 'spectral content' (basically, the mix of frequencies) of the accompaniment music. Using this information, it generates at least one harmony note. A clever part is its ability to detect and ignore 'unintentional strums' from stringed instruments, like when a guitarist accidentally brushes strings during a chord change, so it doesn't mess up the generated harmony. It can even output these harmonies as MIDI data or mix them with the original sounds for real-time performance.
The clever bit
The innovation lies in the system's ability to not only generate harmonies but also to intelligently filter out unwanted musical 'noise,' specifically unintentional strums on stringed instruments, ensuring the generated harmony remains musically coherent.
What it does not cover
- Generating harmonies without analyzing the spectral content of an accompaniment signal
- Generating harmonies without identifying a current melody note
- Harmony generation that does not suppress determination based on an unintentional strum
- Methods that do not involve receiving at least one polyphonic electrical signal from a multi-stringed instrument
- Detecting unintentional strums without comparing received notes to templates based on open string tuning
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
PatentBrief Score
Impact Score
Moderate
Citation count
28/40
Moderately cited
Claim breadth
20/20
Very broad protection
Recency
5/20
Granted 10–20 years ago
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$86K – $276K
Midpoint $173K · 1.2 yr remaining · industry ×1.5
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
0 independent claims · 1 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
78 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Campbell, W. N., Lupini, P. R., & Rutledge, G. A. (2012). How to Automatically Generate Musical Harmonies from Audio (U.S. Patent No. 8,168,877). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/8168877/musical-harmony-generation-from-polyphonic-audio-signals
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
Embed
Add this patent to your site
Drop this plain-English patent card into any blog post or article — free, no signup. It always links back to the full breakdown here.
<div data-patentlens-widget data-patent-number="US8168877"></div> <script src="https://patentbrief.org/embed.js" async></script>
Stay in the loop
Get a weekly digest of new patents.
One email per week. No spam. Unsubscribe anytime.
Keep exploring
Related patents you should know
US 4683195 · 1987
How to Make Billions of Copies of a DNA Segment
This patent describes the Polymerase Chain Reaction (PCR), a method to rapidly create many copies of a specific piece of DNA or RNA, enabling its detection and analysis.
Cetus Corp
US 8697359 · 2014
How to Edit Genes in Human Cells Using an Engineered CRISPR System
This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms.
Massachusetts Institute of Technology
US 7657849 · 2010
How the iPhone's Slide-to-Unlock Gesture Works
Apple's 2010 patent describes unlocking a device by dragging a specific graphical image across the touchscreen along a predefined path, a gesture that became iconic with the original iPhone.
Apple Inc
US 4733665 · 1988
How Doctors Implant a Permanent Stent Using a Balloon
This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open.
Expandable Grafts Partnership
US 4965188 · 1990
How to Make Many Copies of a DNA Piece with Heat
This patent describes the Polymerase Chain Reaction (PCR) method, a technique to make millions of copies of a specific DNA segment using a heat-resistant enzyme and repeated temperature changes.
Cetus Corp
US 4235871 · 1980
How to Encapsulate Active Materials in Lipid Bubbles Efficiently
This patent describes a method for trapping biologically active substances inside tiny, multi-layered fat bubbles called liposomes, using a specific water-in-oil emulsion and gel-forming process to improve how much material gets captured.
Individual
Semantically similar
You might also find these interesting
US 5973252 · 1999 · Auburn Audio Technologies Inc
How Real-Time Pitch Correction and Auto-Tune Technology Works
US 12277178 · 2025 · Spotify AB
How Music Apps Learn What You Don't Want in Playlists
US 5579430 · 1996 · Fraunhofer Gesellschaft zur Foerderung der Angewandten Forschung eV
How Digital Audio Compression Works
US 11361763 · 2022 · Amazon Technologies
How Smart Speakers Know You're Talking to Them After a Command
More to explore
More in Consumer Electronics
US 7657849 · 2010 · Apple Inc
How the iPhone's Slide-to-Unlock Gesture Works
US 7479949 · 2009 · Apple Inc
How Touchscreens Understand Your Finger Swipes and Scrolls
US 4528643 · 1985 · FPDC Inc
How Stores Make Custom Products On-Demand with Remote Approval
US 7469381 · 2008 · Apple Inc
How Touchscreens Show and Snap Back When You Scroll Past an Edge
New to patents?
Common Questions
Frequently Asked Questions
What does How to Automatically Generate Musical Harmonies from Audio cover?
This 2012 patent describes a system that listens to music and automatically generates harmony notes to accompany a melody, even detecting and ignoring accidental strums on stringed instruments.
Who owns patent US 8168877?
Harman International Industries Canada Ltd owns this patent, granted in 2012.
When does this patent expire?
This patent is expected to expire on October 2, 2027, when the invention enters the public domain.
What is patent US 8168877 cited by?
This patent has been cited by 24 later patents that build on its ideas.
What problem does this patent solve?
This patent addresses a core challenge in music production: creating convincing instrumental accompaniments and harmonies automatically. It provides a technical solution for software and hardware that can assist musicians, from hobbyists to professionals, in arranging and performing music by intelligently adding harmonic layers.
What does this patent NOT cover?
Generating harmonies without analyzing the spectral content of an accompaniment signal
Patent monitoring