Earpiece Back-EMF Sensing for High-Frequency Noise Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing active noise cancellation (ANC) technologies, particularly feedback ANC, face limitations due to the need for a microphone to detect ambient noise, which can result in delays and reduced effectiveness in canceling high-frequency sounds, and are unable to detect physical and biological activities without sensors.
Innovation Solution
A system and method that utilize differential amplifiers and current/voltage output amplifiers to detect and adjust signals representative of environmental effects on electrical loads, such as ambient noise, without the need for a microphone, by leveraging the 'microphone effect' of electroacoustic transducers to provide a signal for noise suppression and detecting biological/physical activities through reverse audio signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microphone is used to detect ambient noise in feedback ANC, then noise cancellation can be implemented, but the proximity requirement between microphone and earpiece driver causes delays that prevent effective cancellation of high frequency sounds
Solution Approach 1:
The patent extracts the noise detection function from a separate microphone component and integrates it into the earpiece driver itself. The driver's back electromotive force (EMF) signal, which naturally contains ambient noise information, is used as the feedback signal, eliminating the need for a physically separate microphone and thus removing the spatial delay issue.
Solution Approach 2:
The earpiece driver is made multi-functional: it serves both as the audio output transducer and as the noise detection sensor. By utilizing the back EMF effect, the same component that converts electrical signals to acoustic signals also converts acoustic signals (ambient noise) back to electrical signals, eliminating the need for separate components.
2Measurement precision
If a microphone is placed near or in the earpiece for feedback ANC, then ambient noise can be detected, but additional hardware components increase device complexity
Solution Approach 1:
The earpiece driver performs dual functions: audio playback and ambient noise detection. The back EMF signal generated by the driver during operation contains both the drive signal information and the ambient noise information, allowing one component to replace what would traditionally require separate microphone hardware.
Solution Approach 2:
The system uses its own operational signal (the back EMF from the driver) to achieve noise detection. The driver essentially monitors its own electrical characteristics, which are influenced by ambient acoustic pressure, thereby self-serving the detection function without requiring external sensing hardware.
3Adaptability or versatility
If traditional ANC methods are used, then ambient noise suppression is achieved, but the ability to detect physical and biological activities without additional sensors is limited
Solution Approach 1:
The back EMF signal from the earpiece driver serves multiple purposes: it provides the feedback signal for noise cancellation and simultaneously contains information about user activities such as jaw movement, swallowing, and muscle contractions. This single signal source enables both ANC and biometric monitoring without additional sensors.
Solution Approach 2:
The system monitors its own operational characteristics (back EMF variations) to detect both acoustic environment changes and physiological activities. The driver's electrical response to mechanical movements from user activities is captured within the same feedback signal used for noise control, enabling activity recognition as a secondary function.
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 enhances noise cancellation, particularly at higher frequencies, eliminates the need for additional hardware like microphones, and allows for the detection of various user activities, improving the listening experience and enabling more precise signal processing.
Implementation Method 1
the 'microphone effect' of electroacoustic transducers to provide a signal for noise suppression
Data Source
AI summary
An improved system and method for recognizing an audio signal due to physical activity and taking a predetermined action in response is disclosed. A “reverse noise signal” created by the sound pressure wave of the physical activity acting on the earpiece transducer is obtained. In some embodiments, an ambient noise signal is inverted and fed back, and the inverted signal is added to the intended audio signal being sent to the earpiece so that the ambient noise is cancelled. In other embodiments, a processor receives the ambient noise signal and predicts the modification to the intended audio signal needed to counteract the ambient noise. In other embodiments, the reverse noise signal may represent a motor or biological activity of a user; the system may take different actions in response to different physical activities, such as a heart beat of the user, or a tap, footfall, or swallowing by the user.