Hands-free Microphone Noise Equalization for Vehicle Call Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hands-free call systems, especially on vehicles, road noise causes significant variations in noise characteristics among microphones, leading to discomforting changes in noise quality when switching input signals, as existing noise correction methods are inadequate for dynamic road noise conditions.
Innovation Solution
A hands-free control apparatus with an identifying unit, noise characteristics adjusting unit, and switching unit that identifies the active microphone and adjusts noise characteristics across microphones to be equal at each frequency, ensuring consistent noise quality during signal switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple microphones are used for hands-free call, then speech capture capability is improved, but noise characteristics vary significantly causing discomfort to the person on the other end
Solution Approach 1:
The patent applies parameter changes by adjusting the gain of each microphone's input signal based on measured noise characteristics. Specifically, the system measures noise levels in different frequency bands for each microphone, calculates appropriate gain values, and applies these gains to equalize the noise characteristics across all microphones. This allows the system to maintain multiple microphone inputs while compensating for individual noise differences, thereby resolving the contradiction between improved speech capture and reduced noise quality variation.
2Adaptability or versatility
If microphones are used for multiple functions (hands-free call, speech recognition, ANC), then versatility is improved, but acoustic characteristics vary depending on function and installation position causing noise quality changes
Solution Approach 1:
The patent applies preliminary action by measuring and storing the noise characteristics of each microphone in advance, before actual call usage. The system performs noise level measurements in different frequency bands during installation or initialization, calculates compensation gain values, and stores these parameters for later use. This preliminary characterization allows the system to quickly compensate for noise differences during hands-free calls, speech recognition, or ANC operations without real-time measurement, thereby maintaining noise quality consistency across multiple functions.
3Measurement precision
If background noise correction is performed by matching with whole room noise level, then identification accuracy is improved, but noise characteristics at different frequencies are not equalized
Solution Approach 1:
The patent applies segmentation by dividing the noise correction process into frequency band segments. Instead of applying a single background noise correction value to all frequencies, the system measures and corrects noise characteristics separately in multiple frequency bands (e.g., low frequency, mid frequency, high frequency). This segmented approach allows independent optimization of noise equalization at each frequency, achieving both accurate microphone identification and uniform noise characteristics across the entire frequency spectrum.
Data Source
AI summary
Characteristics of noise contained in input signals of a plurality of microphones are adjusted to be equal to each other at each frequency, and an input signal of a microphone identified to be a microphone through which a speaker has input uttered speech from among the microphones subjected to adjustment of the noise characteristics is switched to a signal to be transmitted to a person on another end of call.