# 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. - **Patent:** US 8168877 - **Original title:** Musical harmony generation from polyphonic audio signals - **Owner:** Harman International Industries Canada Ltd - **Granted:** 2012 - **Status:** Active - **Times cited:** 24 - **Field:** consumer_electronics, software, telecommunications ## What it does 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. ## 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 ## 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. ## Real-world examples 1. Music production software (DAWs) with auto-harmony features 2. Digital audio workstations (DAWs) 3. Live performance accompaniment systems 4. Virtual instrument plugins ## Why it matters 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. ## 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 **Full plain-English explainer:** https://patentbrief.org/patent/us/8168877/musical-harmony-generation-from-polyphonic-audio-signals **Original patent:** https://patents.google.com/patent/US8168877 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Real-Time Pitch Correction and Auto-Tune Technology Works](https://patentbrief.org/patent/us/5973252/auto-tune-pitch-correction) — A method for detecting the pitch of a musical note and adjusting it to a target frequency in real time using auto-correlation. - [Smart Speaker System Adapts Sound Based on Speaker Placement](https://patentbrief.org/patent/us/11743673/audio-processing-apparatus-and-method-therefor) — This patent describes an audio system that intelligently chooses how to play different parts of a sound through different speakers, adapting its method based on where each speaker is placed in a room. - [How Smart Speakers Adapt Sound to Your Room and Listening Spot](https://patentbrief.org/patent/us/11178503/system-for-rendering-and-playback-of-object-based-audio-in-various-listening-env) — This patent describes a system that automatically adjusts how spatial audio sounds in a room by sensing speaker locations, listener position, and room acoustics, then dynamically calibrating the sound output. - [How Streaming Services Automatically Build Custom Radio Stations](https://patentbrief.org/patent/us/10108619/microsoft-edge-browser) — A method for streaming services to create custom music radio stations by analyzing genre percentages and artist relationships to pick the best songs. - [How a Device Renders Immersive Sound Objects Using Speaker Virtualization](https://patentbrief.org/patent/us/10743125/audio-processing-apparatus-with-channel-remapper-and-object-renderer) — Dolby's patent describes an audio processing system that takes individual sound elements, like a buzzing bee, and places them precisely in a 3D space using smart software that makes speakers sound like they are in different locations.