Wearable Hearing ANC Feedback Loop With Low Phase Delay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Active Noise Canceling (ANC) systems struggle to effectively cancel non-stationary noises, such as those caused by mechanical movements and microphonic effects, due to phase lag issues in hardware components like condenser microphones and dynamic drivers, which result in incomplete noise suppression.
Innovation Solution
A system with near-zero phase delay is implemented within a wearable hearing device, utilizing a sound producing device, a sound sensing device, and a subtraction circuit to form a feedback loop that minimizes phase delay between the driving voltage and sensed signal, allowing for real-time noise cancellation of both stationary and non-stationary noises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ANC systems use condenser microphones and dynamic drivers, then the system can function with standard hardware components, but phase lag of 180° or more occurs making real-time noise cancellation ineffective
Solution Approach 1:
The patent replaces the conventional condenser microphone with a piezoelectric microphone and the dynamic driver with a piezoelectric actuator. This substitution eliminates the C-R circuit phase lag and mechanical inertia delays, achieving near-zero phase delay in the feedback loop and enabling effective real-time noise cancellation.
Solution Approach 2:
The patent changes the fundamental operating parameters of the sensing and actuating components by using piezoelectric materials instead of conventional electromagnetic components. This parameter change transforms the system from having 180°+ phase lag to near-zero phase lag, fundamentally resolving the time delay issue.
2Adaptability or versatility
If conventional ANC systems assume stationary noise, then the system design can use standard transfer functions with phase lag, but the system fails to cancel non-stationary impulsive noises effectively
Solution Approach 1:
The patent transitions from a static ANC model assuming stationary noise to a dynamic model that handles non-stationary impulsive noises. By using piezoelectric components with near-zero phase delay, the system can respond in real-time to rapidly changing noise amplitudes and frequencies, making the ANC effective for both stationary and non-stationary noise types.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables effective cancellation of both stationary and non-stationary noises, including those from occlusion and microphonic effects, by reducing phase lag to less than 60°, resulting in improved noise suppression and a more accurate reproduction of desired sound pressure.
Implementation Method 1
a piezoelectric microphone instead of a conventional condenser microphone... the piezoelectric microphone would exhibit near-zero phase delay from sound pressure to voltage signal conversion
Implementation Method 2
a piezoelectric actuator instead of a conventional dynamic driver... the piezoelectric actuator would exhibit minimal phase delay from voltage signal to sound pressure generation
Data Source
AI summary
A system, disposed within a wearable hearing device, includes a sound producing device (SPD) driven by a driving voltage, a first sound sensing device, and a subtraction circuit. The first sound sensing device is configured to sense a combined sound pressure produced at least by the SPD and generate a sensed signal accordingly. The subtraction circuit has a first input terminal, a second input terminal, and a first output terminal. The first input terminal is coupled to the first sound sensing device, and the first output terminal is coupled to the SPD. A first phase delay between the driving voltage and the sensed signal is less than 60°.