How Digital Audio Compression Saves Space by Copying Frequencies
A method for shrinking audio files by only saving the lower-pitched sounds and using clever math to reconstruct the higher-pitched sounds from them.
Original patent title: “USRE47935E1 - Encoding device and decoding device”
A method for shrinking audio files by only saving the lower-pitched sounds and using clever math to reconstruct the higher-pitched sounds from them. Granted to Dolby International AB in 2020 with 34 claims.
Key facts
Coverage
What does this patent actually cover?
This patent describes a way to compress digital audio by splitting a sound signal into two parts: a lower frequency range that is saved in full, and a higher frequency range that is reconstructed. Instead of saving all the high-frequency data, the encoder identifies a specific 'partial spectrum' from the lower range and copies it to represent the higher range. It then sends a few parameters—like a gain factor to adjust volume and a toggle to invert the signal—to tell the decoder exactly how to transform that copied piece to sound like the original high frequencies. This significantly reduces the amount of data needed to transmit or store high-quality audio.
The gap
What does this patent NOT cover?
- Does not cover audio compression that saves the entire high-frequency spectrum without using frequency copying or band extension.
- Does not cover methods that do not use the specific third parameter for frequency domain inversion of the copied spectrum.
- Does not cover the physical hardware of microphones or speakers used to capture or play back the audio.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation lies in the third parameter that dictates whether the copied lower-frequency spectrum should be inverted in the frequency domain, allowing the decoder to better match the harmonic characteristics of the original high-frequency signal.
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
High-efficiency audio codecs used in mobile voice calling (VoLTE)
Streaming audio services that adapt quality based on network speed
Digital radio broadcasting systems
Why it matters
The bigger picture
Efficient audio compression is the backbone of modern streaming services and telecommunications. By allowing high-fidelity sound to be transmitted using less bandwidth, this technology enables clear voice calls over mobile networks and high-quality music streaming on limited data plans. Dolby International maintains this as part of a broader portfolio that defines how audio is handled in digital broadcast and internet standards.
Filed
July 27, 2017
Granted
April 7, 2020
Market context
Who's building on this
Companies in this space
Dolby International continues to be the primary entity managing this intellectual property. Major telecommunications equipment manufacturers and smartphone chipset designers integrate these types of bandwidth-extension techniques into their audio processing pipelines to meet industry standards for efficient data transmission.
Market impact
This technology supports the transition to high-definition voice and audio streaming by lowering the barrier of data consumption. It has helped standardize how audio codecs handle high-frequency reconstruction, which is essential for maintaining audio clarity in bandwidth-constrained environments like mobile cellular networks.
Claim 1 — Plain English
What this patent covers
This patent describes a way to compress digital audio by splitting a sound signal into two parts: a lower frequency range that is saved in full, and a higher frequency range that is reconstructed. Instead of saving all the high-frequency data, the encoder identifies a specific 'partial spectrum' from the lower range and copies it to represent the higher range. It then sends a few parameters—like a gain factor to adjust volume and a toggle to invert the signal—to tell the decoder exactly how to transform that copied piece to sound like the original high frequencies. This significantly reduces the amount of data needed to transmit or store high-quality audio.
The clever bit
The innovation lies in the third parameter that dictates whether the copied lower-frequency spectrum should be inverted in the frequency domain, allowing the decoder to better match the harmonic characteristics of the original high-frequency signal.
What it does not cover
- Does not cover audio compression that saves the entire high-frequency spectrum without using frequency copying or band extension.
- Does not cover methods that do not use the specific third parameter for frequency domain inversion of the copied spectrum.
- Does not cover the physical hardware of microphones or speakers used to capture or play back the audio.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Early stage
Citation count
0/40
No citations yet
Claim breadth
20/20
Very broad protection
Recency
10/20
Granted 5–10 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
$45K – $144K
Midpoint $90K · 11.1 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.
The original legal language
Original claims
34 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Nishio, K., Norimatsu, T., Tanaka, N., & Tsushima, M. (2020). How Digital Audio Compression Saves Space by Copying Frequencies (U.S. Patent No. RE47,935). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/RE47935/google-chrome-browser
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="USRE47935"></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
More to explore
More in Telecom & Wireless
US 5347632 · 1994 · Prodigy Services Co
Prodigy's System for Interactive Online Information and Shopping
US 3906166 · 1975 · Motorola Inc
How Early Cell Phones Handled Calls Across Different Towers
US 4063220 · 1977 · Xerox Corp
How Multiple Computers Share a Network Cable Without Crashing
US 4200770 · 1980 · Leland Stanford Junior University
How to Create a Secret Code Key Without Meeting First
New to patents?
Common Questions
Frequently Asked Questions
What does How Digital Audio Compression Saves Space by Copying Frequencies cover?
A method for shrinking audio files by only saving the lower-pitched sounds and using clever math to reconstruct the higher-pitched sounds from them.
Who owns patent US RE47935?
Dolby International AB owns this patent, granted in 2020.
When does this patent expire?
This patent is expected to expire on April 7, 2040, when the invention enters the public domain.
What problem does this patent solve?
Efficient audio compression is the backbone of modern streaming services and telecommunications. By allowing high-fidelity sound to be transmitted using less bandwidth, this technology enables clear voice calls over mobile networks and high-quality music streaming on limited data plans. Dolby International maintains this as part of a broader portfolio that defines how audio is handled in digital broadcast and internet standards.
What does this patent NOT cover?
Does not cover audio compression that saves the entire high-frequency spectrum without using frequency copying or band extension.
Patent monitoring