Stereo Headphone Crosstalk Removal via Digital Signal Processing
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Solution Overview
Problem
Stereo headphones with finite ground resistance cause crosstalk between left and right channels, resulting in signal interference, which degrades audio fidelity.
Innovation Solution
Implementing a crosstalk removal function by adding a constant factor y times the right input voltage to the left input voltage and vice versa, calculated using the load resistance and common ground resistance, to eliminate signal interference between channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common ground path is used for both left and right channels in stereo headphones, then the device complexity is reduced, but crosstalk between channels occurs due to finite ground resistance
Solution Approach 1:
The patent introduces an intermediary processing stage (crosstalk removal circuit or digital signal processing block) that mediates between the shared ground path and the audio channels. This intermediary component compensates for the crosstalk effect by calculating and subtracting the leaked signal from one channel from the other channel, thereby resolving the contradiction between using a simple common ground path and eliminating crosstalk interference
2Reliability
If crosstalk removal processing is applied to eliminate signal interference, then signal fidelity is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent replaces complex hardware-based crosstalk elimination circuits with digital signal processing algorithms. Instead of using additional analog components and circuits to physically eliminate crosstalk, the invention uses mathematical operations (multiplication by constant factors and addition/subtraction) on the digital audio signals to achieve the same effect, thereby improving signal fidelity while minimizing the increase in device complexity
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
Effectively reduces crosstalk by increasing each channel's digital input voltage, thereby enhancing signal fidelity and minimizing signal interference between the left and right audio channels.
Implementation Method 1
Stereo headphones often have a finite resistance in their ground path that is common to both the left and right channels. This finite ground resistance may cause crosstalk between the left and right channels of a stereo headphone
Data Source
AI summary
Techniques for removing crosstalk from a system, e.g., an audio system, having first and second (e.g., left and right) channels. In an aspect, first and second output voltages of corresponding first and second amplifiers are sampled during a calibration mode, in which one of the amplifiers is driven with a reference voltage, and the output of the other of the amplifiers is configured to have a high impedance. The sampled first and second output voltages may be digitized for processing by a processor to estimate a crosstalk removal function. The crosstalk removal function may then be multiplied with the input signals and added in a cross-channel manner to the first and second input signals prior to amplification to remove crosstalk from the system. In certain aspects, multiple reference voltages may be applied during the calibration mode to improve the estimate of the crosstalk removal function.