DCT
2:25-cv-00141
Ear Technology Corp v. Puretone Ltd
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Ear Technology Corporation (Tennessee)
- Defendant: Puretone Ltd (United Kingdom)
- Plaintiff’s Counsel: Luedeka Neely, Graham.
- Case Identification: 2:25-cv-00141, E.D. Tenn., 09/09/2025
- Venue Allegations: Plaintiff alleges venue is proper because Defendant is a foreign corporation subject to personal jurisdiction in the district and because a substantial part of the events giving rise to the claims occurred in the district.
- Core Dispute: Plaintiff alleges that Defendant’s DefendEar line of hearing protection devices infringes three U.S. patents related to user-selectable audio programs and multipurpose controls for hearing assistance devices.
- Technical Context: The technology at issue concerns in-ear audio devices that allow users to select from multiple pre-programmed sound processing modes and adjust volume using simple, on-device controls, reducing the need for professional fitting.
- Key Procedural History: The complaint alleges a history between the parties, including a 2013 meeting to discuss Plaintiff's products, Defendant's subsequent purchase of Plaintiff's products which were marked with the asserted patents, and a formal notice letter sent in January 2025 detailing the alleged infringement. These allegations form the basis for the willfulness claim.
Case Timeline
| Date | Event |
|---|---|
| 2008-03-14 | Earliest Priority Date for ’968 and ’634 Patents |
| 2009-04-08 | Earliest Priority Date for ’272 Patent |
| 2012-10-09 | U.S. Patent No. 8,284,968 Issues |
| 2013-XX-XX | Plaintiff and Defendant representatives meet to discuss products |
| 2013-06-25 | U.S. Patent No. 8,472,634 Issues |
| 2015-05-12 | U.S. Patent No. 9,031,272 Issues |
| 2025-01-28 | Plaintiff provides Defendant with copies of patents-in-suit |
| 2025-09-09 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,284,968 - "Preprogrammed hearing assistance device with user selection of program"
- Patent Identification: U.S. Patent No. 8,284,968, "Preprogrammed hearing assistance device with user selection of program," issued October 9, 2012 (’968 Patent). (Compl. ¶8).
The Invention Explained
- Problem Addressed: The patent’s background section describes the significant cost and complexity associated with traditional hearing aid fitting, which typically requires an iterative process involving an audiologist, specialized programming equipment, and multiple office visits (’968 Patent, col. 1:21-col. 2:22).
- The Patented Solution: The invention is a hearing assistance device pre-loaded with multiple acoustical configuration programs. The user can cycle through and select the preferred program by pressing a button on the device's housing, eliminating the need for an external computer or programming interface. The device provides audible feedback, such as a series of beeps, to inform the user which program has been selected (’968 Patent, Abstract; col. 8:5-25).
- Technical Importance: This approach aimed to lower the cost and increase the accessibility of hearing assistance technology by empowering the end-user to perform a significant part of the fitting process themselves (’968 Patent, col. 2:23-34).
Key Claims at a Glance
- The complaint asserts independent claim 23 (Compl. ¶20).
- Claim 23 recites a programmable apparatus comprising:
- A housing configured to be worn on/in/behind the ear.
- Memory within the housing for storing multiple audio processing programs.
- A processor within the housing to execute selected programs.
- A selection device on the housing, operable by the user to select one of the programs.
- A digital-to-analog converter.
- An audio output section for generating audible sound.
- The audio output section is also for generating audible sounds that indicate which program is currently selected.
- The claim concludes with a "whereby" clause stating the selected program can be determined without connecting to an external device.
- The complaint does not explicitly reserve the right to assert dependent claims.
U.S. Patent No. 8,472,634 - "Preprogrammed hearing assistance device with audiometric testing capability"
- Patent Identification: U.S. Patent No. 8,472,634, "Preprogrammed hearing assistance device with audiometric testing capability," issued June 25, 2013 (’634 Patent). (Compl. ¶11).
The Invention Explained
- Problem Addressed: In addition to the fitting complexity described in the ’968 Patent, this patent addresses the need for a formal audiometric test performed by a clinician to establish a user's initial hearing profile (’634 Patent, col. 2:5-16).
- The Patented Solution: The patent describes a device with a built-in audiometric testing mode where the device itself generates test tones. The user adjusts the volume to their hearing threshold and presses a button to set the level for each frequency, allowing the device to create its own amplification profile (’634 Patent, Abstract). While the patent title focuses on audiometric testing, the asserted claims focus on a related innovation: using a single switching device for dual functions, such as program selection and volume control, to simplify the user interface.
- Technical Importance: This technology further simplifies the process of obtaining a hearing device by integrating the initial hearing test into the device itself, potentially removing another barrier to access for users (’634 Patent, col. 2:7-16).
Key Claims at a Glance
- The complaint asserts independent claims 17 and 20 (Compl. ¶¶28, 35).
- Claim 17 recites a programmable apparatus with a housing, processor, memory, switching device, and other standard components for switching between available programs.
- Claim 20 recites a programmable apparatus with a single "switching device" that is operable in two distinct modes:
- A "program switching mode" where the user can switch between available audio processing programs.
- A "volume control mode" where the user can adjust the volume of the audible sound.
- The complaint does not explicitly reserve the right to assert dependent claims.
U.S. Patent No. 9,031,272 - "Hearing assistance apparatus having single multipurpose control device and method of operation"
- Patent Identification: U.S. Patent No. 9,031,272, "Hearing assistance apparatus having single multipurpose control device and method of operation," issued May 12, 2015 (’272 Patent). (Compl. ¶14).
Technology Synopsis
The ’272 Patent claims a method for controlling a hearing assistance device that has a single multipurpose control. The method distinguishes between different user inputs to the same control: "tapping" the control adjusts the volume, while "pressing and holding" the control for an extended time discontinues one amplification algorithm and initiates another (’272 Patent, Abstract). This patent focuses on the specific user actions for operating a dual-function control.
Asserted Claims
Independent claim 7 (Compl. ¶40).
Accused Features
The complaint alleges that the DefendEar Devices practice this method, whereby a "short press" of the on-device control adjusts volume and a "long press" of the same control switches between the device's "modes," which are alleged to be amplification algorithms (Compl. ¶¶43-44).
III. The Accused Instrumentality
Product Identification
The DefendEar DigitalX5 and DefendEar DigitalX3 hearing protection devices (collectively, "DefendEar Devices") (Compl. ¶18).
Functionality and Market Context
The DefendEar Devices are in-ear apparatuses that provide hearing protection while also offering sound processing capabilities (Compl. ¶18). According to the complaint, the devices feature multiple user-selectable "modes," which are alleged to be audio processing programs stored in the device's memory (Compl. ¶22). A user can switch between these modes using a control mechanism on the device's housing (Compl. ¶23). The complaint alleges this same control mechanism is also used to adjust volume (Compl. ¶38). The devices are alleged to provide "vocal feedback" to inform the user which mode is currently active (Compl. ¶26). A visual from the product manual shows the button controls for "Incremental Mode Selection" and "Incremental Mode De-selection" (Compl. ¶23).
IV. Analysis of Infringement Allegations
’968 Patent Infringement Allegations
| Claim Element (from Independent Claim 23) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a housing configured to be worn in, on or behind an ear of the person | The DefendEar Devices include a housing designed to be worn on an ear. A product manual diagram illustrates how the earpiece is seated in the ear canal and secured by the helix lock (Compl. ¶21). | ¶21 | col. 2:38-40 |
| memory disposed within the housing, the memory for storing a plurality of audio processing programs that may be used in processing digital audio signals | The devices have memory that stores multiple selectable "modes," which are alleged to be audio processing programs. | ¶22 | col. 6:33-41 |
| a processor disposed within the housing and connected to the memory, the processor operable to execute one or more selected audio processing programs to process digital audio signals | The complaint alleges this element is met by the devices' ability to execute the selected "modes." | ¶22 | col. 6:13-16 |
| a selection device disposed on the housing and connected to the processor, the selection device operable by the person to select one of the audio processing programs... | The devices have a "mode selection mechanism" on the housing. A product manual diagram depicts buttons for "LONG PRESS UP" and "LONG PRESS DOWN" for mode selection (Compl. ¶23). | ¶23 | col. 6:10-13 |
| a digital-to-analog converter disposed within the housing... | The complaint alleges a DAC is an "inherent component of a digital hearing device." | ¶24 | col. 6:18-20 |
| an audio output section disposed within the housing...for...generating audible sound... | The devices include an audio output section that provides audible sound to the user and includes a volume control. | ¶25 | col. 6:21-28 |
| the audio output section further for generating one or more audible sounds that indicate to the person which one of the audio processing programs is currently selected... | The devices provide "vocal feedback" which "vocally advises you which mode you are using." | ¶26 | col. 8:11-13 |
| whereby the currently selected audio processing program can be determined without having to connect the apparatus to any external device. | The vocal feedback feature is alleged to not be dependent on a connection to an external device, such as a smartphone. | ¶27 | col. 6:5-9 |
’634 Patent Infringement Allegations
Claim Chart Summary for Independent Claim 20
| Claim Element (from Independent Claim 20) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a switching device disposed on one of the housings...the switching device for operating in a program switching mode in which the switching device is operable by the person to switch from one of the available audio processing programs to another... | The DefendEar Devices include a switching device for changing modes. A product manual diagram titled "MODE SELECTION" shows buttons for selecting different programs (Compl. ¶37). | ¶37 | col. 19:45-53 |
| the switching device further for operating in a volume control mode in which the switching device is operable by the person to adjust the volume of audible sound generated by the audio output section | The same switching device is also used to adjust volume. A product manual diagram titled "ADJUSTING VOLUME" shows that a "SHORT PRESS UP" increases volume and a "SHORT PRESS DOWN" decreases volume using the same physical controls (Compl. ¶38, ¶43). | ¶38 | col. 19:53-58 |
| a digital-to-analog converter disposed within at least one of the housings... | The complaint alleges a DAC is an "inherent component of a digital hearing aid." | ¶32 | col. 4:10-13 |
| the audio output section including an amplifier for receiving and amplifying the output analog audio signals, and including a transducer for generating audible sound based thereon and providing the audible sound to the person. | The complaint alleges that some modes include "amplification" and that it is inherent that the devices include a transducer to generate sound from the amplified signals. | ¶39 | col. 4:13-22 |
Identified Points of Contention
- Scope Questions: A central question for the ’634 and ’272 Patents will be whether a single physical control that responds differently to a "short press" versus a "long press" meets the claim limitations of operating in distinct "modes" ("program switching mode" vs. "volume control mode") or performing the distinct method steps of "tapping" vs. "pressing and holding".
- Technical Questions: What is the technical nature of the accused "modes"? A point of contention may be whether they constitute "audio processing programs" or "amplification algorithms" as contemplated by the patents, or if they are merely simple filters or settings that fall outside the claims' scope. The complaint does not provide sufficient detail for analysis of the technical implementation of the accused "modes."
- Another technical question is whether the "vocal feedback" of the accused devices meets the ’968 Patent's requirement for "one or more audible sounds that indicate" the selected program. While the patent specification primarily describes beeps, the claim language is not explicitly so limited, raising a question of construction.
V. Key Claim Terms for Construction
Term 1 (’968 Patent, cl. 23)
- The Term: "audio processing programs"
- Context and Importance: This term is fundamental to infringement of all asserted patents. The analysis will depend on whether the accused "modes" fall within the scope of this term. Practitioners may focus on this term because Defendant could argue its "modes" are simple environmental settings, not the complex, prescription-style "programs" (e.g., NAL, POGO) described as examples in the patent specifications.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The ’968 Patent specification describes a "primary acoustical characteristic configuration program" as an "algorithm that sets the audio frequency shaping or compensation provided in the processor 16" (’968 Patent, col. 7:5-8). This functional definition may be broad enough to encompass the accused "modes."
- Evidence for a Narrower Interpretation: The specification provides examples of such programs that are well-known, prescription-based audiological algorithms like "NAL," "Berger," and "POGO" (’968 Patent, col. 7:10-20). This could support an argument that the term is limited to such comprehensive, clinically-derived algorithms.
Term 2 (’634 Patent, cl. 20)
- The Term: "a switching device...for operating in a program switching mode...[and] further for operating in a volume control mode"
- Context and Importance: Infringement of claim 20 of the ’634 Patent hinges on whether a single physical control, differentiated by press duration, constitutes a device operating in two distinct "modes." The outcome of this construction could be dispositive for this claim.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent does not define how the device must switch between its "modes" of operation. The claim requires that the switching device be for operating in these two modes, which could be interpreted to cover a device designed to respond differently (program change vs. volume change) to different types of user input (long vs. short press). The patent family describes using press duration to differentiate between cycling through programs and selecting a program (’968 Patent, col. 8:26-47).
- Evidence for a Narrower Interpretation: A defendant could argue that "mode" implies a more persistent state that the device enters, rather than an instantaneous response to a specific input type. The specification for the ’968 patent, which is in the same family, discusses a "Configuration Mode" that is entered through a specific sequence of actions, suggesting "mode" implies a distinct and formally entered state of operation (’968 Patent, col. 15:52-60).
VI. Other Allegations
- Indirect Infringement: The complaint alleges inducement of infringement under 35 U.S.C. § 271(b) across all three patents. The allegations are based on Defendant's creation and dissemination of "promotional and marketing materials, supporting materials, instructions, [and] product manuals" that allegedly instruct and encourage end-users to operate the DefendEar Devices in an infringing manner (Compl. ¶¶51, 59, 66).
- Willful Infringement: The complaint alleges willful infringement based on pre-suit knowledge of the patents. The specific facts alleged include a 2013 meeting between the parties to discuss Plaintiff's patented technology, Defendant's purchase of Plaintiff's products that were marked with the patent numbers, and a January 28, 2025 notice letter that explicitly identified the patents and the accused products (Compl. ¶¶45-47, 55, 63, 70).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of claim scope and construction: Can the user input distinction of a "short press" versus a "long press" on a single physical control satisfy the claim language requiring operation in distinct "program switching" and "volume control" "modes," or the performance of distinct method steps like "tapping" versus "pressing"? The resolution of this question will be critical for the allegations concerning the ’634 and ’272 patents.
- A key evidentiary question will be one of technical implementation: Do the accused DefendEar "modes" function as the "audio processing programs" or "amplification algorithms" recited in the claims? This will likely require discovery into the software and hardware of the accused devices to determine if there is a fundamental match in technical operation or merely a superficial similarity in user-facing labels.
- Given the detailed allegations of pre-suit notice dating back to a 2013 meeting, a central question regarding damages will be willfulness: Did the Defendant act with the requisite state of mind to justify an enhancement of damages, should infringement be established? The outcome will depend on the evidence presented regarding the parties' interactions and the defendant's response to acquiring knowledge of the patents.