Sidetone Calibration via Feedback Microphone
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Solution Overview
Problem
Existing personal audio devices, such as wireless telephones, often provide unnatural sidetone due to obstruction by transducers and housing, which distorts and attenuates the user's voice, and existing solutions do not effectively adapt to changing transducer types, positions, and environmental factors.
Innovation Solution
A system and method for calibrating sidetone in personal audio devices, including adjustable parameters and voice-activity detection, which uses microphones to optimize the sound level and frequency content of the user's voice, incorporating adaptive noise cancellation and frequency shaping to simulate the natural hearing of one's own voice without occlusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transducers and housing are used to deliver audio to the user, then audio playback function is achieved, but the user's voice is distorted and attenuated causing unnatural sidetone
Solution Approach 1:
The system uses a feedback mechanism where the user's voice captured by the microphone is processed and injected back into the transducer output. The sidetone signal is generated by capturing the user's voice through a microphone, processing it through signal processing circuits, and adding it to the transducer output so the user can hear their own voice naturally despite ear obstruction.
Solution Approach 2:
The patent introduces an intermediary signal processing system that captures the user's voice through a microphone, processes it independently, and then combines it with the main audio output. This intermediary path allows the user's voice to be delivered to the ear without being distorted by the transducer housing obstruction.
2Adaptability or versatility
If fixed sidetone parameters are used, then device complexity is reduced, but sidetone quality deteriorates under changing transducer type, position and environmental factors
Solution Approach 1:
The system implements dynamic sidetone parameter adjustment based on detected conditions. The signal processing circuits analyze the user's voice characteristics and environmental factors in real-time, automatically adjusting sidetone parameters such as gain, frequency response, and timing to maintain natural sound quality across different transducer types, positions, and acoustic environments.
Solution Approach 2:
The patent changes multiple parameters of the sidetone signal including gain level, frequency response characteristics, and timing delay based on detected conditions. The system measures the acoustic environment and user's voice properties, then adjusts sidetone parameters dynamically to compensate for variations in transducer position, type, and environmental acoustic conditions.
Data Source
Figure 1A~1B
Figure 2
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AI summary
A personal audio device includes a sidetone circuit with one or more adjustable coefficients that generates a sidetone signal from the output of a first microphone. The sidetone circuit has one or more adjustable coefficients for altering the relationship between the first microphone signal and the sidetone signal. The personal audio device also includes a transducer for reproducing playback audio and the sidetone signal at an ear of a listener and a second microphone for measuring the output of the transducer as delivered to the ear of the listener. The sidetone circuit includes a calibration circuit for estimating a response of the second microphone to the sidetone signal and adjusting the coefficient of the sidetone circuit according to the estimated response.