Vehicle Acoustic Processing System for Echo Cancellation
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Solution Overview
Problem
In vehicles, far-field microphones capture both desired and undesired audio signals, leading to issues like echo and feedback, which cause howling and noise, due to the small cabin size and proximity of drivers and passengers, making it difficult to maintain clear communication and entertainment without distortion.
Innovation Solution
An acoustic processing system that uses adaptive filters to model loudspeaker-to-microphone impulse responses for echo and feedback cancellation, combined with a synthesizer to decorrelate reinforcement signals and add audio effects, ensuring clear and enhanced vocal entertainment by removing unwanted echoes and feedback while maintaining a consistent signal level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If far-field microphones are used to capture audio signals in a vehicle cabin, then the system can capture speech from multiple zones, but echo and feedback cause howling and noise that degrade signal quality
Solution Approach 1:
The system divides the vehicle cabin into multiple acoustic zones and uses separate adaptive filters for each zone. Each filter independently models the impulse response from specific loudspeakers to the microphone, allowing the system to process and cancel echo/feedback from different spatial regions separately, thereby maintaining multi-zone speech capture capability while reducing overall echo and feedback noise
Solution Approach 2:
The patent introduces an acoustic model as an intermediary that represents the physical echo and feedback paths between loudspeakers and microphones. This model serves as a mediator that enables the system to understand and cancel the harmful acoustic interactions without requiring direct measurement of all possible paths, thus resolving the contradiction between comprehensive speech capture and echo suppression
2Measurement precision
If acoustic reinforcement is applied to enhance speech signals, then communication clarity improves, but feedback loops create howling and distortion
Solution Approach 1:
The system performs preliminary modeling of the acoustic transfer functions from loudspeakers to microphones before applying acoustic reinforcement. By pre-characterizing the echo and feedback paths, the system can anticipate and cancel the harmful feedback effects before they manifest as howling, while still applying the necessary reinforcement to maintain speech clarity
Solution Approach 2:
The patent implements a feedback cancellation mechanism where the modeled impulse responses are used to generate anti-echo signals that are subtracted from the captured audio. This creates a negative feedback loop that actively counteracts the positive feedback causing howling, allowing acoustic reinforcement to be applied safely while maintaining speech clarity
3Volume of moving object
If the vehicle cabin size is reduced for compactness, then manufacturing cost decreases, but acoustic coupling between loudspeakers and microphones increases causing feedback
Solution Approach 1:
The system changes the parameters used to model the acoustic environment by implementing zone-specific impulse response models rather than a single global model. This allows the system to account for the intensified acoustic coupling in compact cabins by treating different regions with tailored parameters, thereby managing feedback complexity without requiring larger physical dimensions
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
The system effectively cancels echo and feedback, providing clear and polished vocal entertainment by isolating desired signals and adding audio effects, enhancing the perceived quality of speech and music, and maintaining a consistent signal level even in noisy conditions.
Implementation Method 1
An acoustic processing system that uses adaptive filters to model loudspeaker-to-microphone impulse responses for echo and feedback cancellation
Data Source
AI summary
A system and method that enhances spoken utterances and provides entertainment by capturing one or more microphone signals containing echo and decomposing the one or more microphone signals into a plurality of signal paths through a synthesizer that adds or makes non-linear modifications to some of the captured one or more microphone signals. The system and method and estimates multiple echo paths from each of the one the one or more microphones. The system and method processes the captured microphone signals in response to the estimated plurality of echo paths by subtracting the echo contributions of each of the plurality of echo paths from the captured one or more microphone signals. The system and method also provide signal separation and post processing functions that renders speech recognition gaming applications.