Ghost Echo Cancellation in Audio Speaker Drivers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ghost echoes, caused by sound pressure reflections captured by speaker drivers, degrade audio quality by mixing with the original audio signal, leading to noise in audio output devices like headphones and earbuds.
Innovation Solution
A sound quality device is introduced to detect, measure, and remove ghost echoes by comparing measured currents with estimated currents using speaker models and characteristics, employing communication interfaces and processing circuits to adjust audio signals and reduce reverse transfer functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If speaker drivers are used to output audio signals, then sound is produced and delivered to the listener, but sound pressure reflections are captured by the speaker drivers creating ghost echoes that degrade audio quality
Solution Approach 1:
The patent implements feedback by capturing the ghost echo current that returns to the speaker driver and using it to generate a cancellation signal. This feedback loop allows the system to detect the harmful reflection and actively counteract it, transforming the harmful feedback into a useful control mechanism for improving audio quality.
Solution Approach 2:
The patent converts the harmful ghost echo current into a beneficial cancellation signal. By capturing the reflected sound pressure and converting it to an electrical signal that can be processed and inverted, the system transforms the harmful feedback into a useful tool for eliminating the echo, effectively using the problem itself to solve the problem.
2Loss of information
If the speaker driver acts as a microphone to capture reflected sound pressure, then ghost current is generated, but this mixes destructively with the original audio signal current
Solution Approach 1:
The patent extracts the ghost echo current from the mixed signal by using signal processing techniques to separate the reflected sound pressure component from the original audio signal. This extraction allows the harmful component to be isolated and processed independently, enabling its cancellation without affecting the original audio information.
Solution Approach 2:
The patent introduces an intermediary processing stage between the speaker driver and the audio output. This intermediary system captures the ghost echo current, processes it to generate a cancellation signal, and then combines this with the original audio signal. The intermediary acts as a mediator that resolves the conflict between the original signal and the harmful reflection.
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 solution effectively minimizes ghost echo currents, enhancing audio quality by isolating and eliminating noise introduced by sound pressure reflections, thereby improving the overall sound output of audio devices.
Implementation Method 1
sound is produced by driving a current through wires to a speaker that outputs the current as sound. The current causes the speaker driver to vibrate or move resulting in the creation of the sound.
Implementation Method 2
Some portion of the sound pressure is captured by the speaker driver acting as a microphone creating current
Implementation Method 3
the sound pressure may be reflected back towards the speaker by the eardrum
Data Source
AI summary
In some examples, devices for detecting and measures a ghost echo current in an audio signal are described. For instance, the device may be configured to sample a current of an audio signal, compare with an expected current, and determine an impulse response of the ghost echo current based on the sampled current and the expected current. The device may also be configured to reduce the ghost echo current using the impulse response.