Formant Enhancement Filter for Body-Conducted Speech Clarity
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Solution Overview
Problem
Existing methods for delivering speech signals through a human body as a medium often result in sound quality degradation due to medium characteristics, leading to unclear signals and echo issues.
Innovation Solution
An apparatus and method that utilize a communicator, actuator, formant enhancement filter, and noise and echo removal filter, controlled by a processor, to estimate formant frequencies, apply filters to enhance sound quality, and remove echoes, thereby improving clarity and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vibration is delivered through the body to transmit speech signal, then speech signal can be delivered through human body as medium, but loss occurs in the delivered speech signal or the delivered speech signal may sound unclear due to being contaminated by noise
Solution Approach 1:
The patent applies preliminary action by pre-processing the speech signal before it is delivered through the human body. A formant enhancement filter is applied to the speech signal in advance to compensate for the expected noise contamination and signal loss that will occur during bodily transmission. This preliminary filtering enhances the formant frequencies that are most susceptible to degradation, ensuring clearer speech delivery despite the harmful effects of noise contamination during transmission.
2Reliability
If strong vibration is used to apply audio signal to the body, then audio signal can be transmitted through human body, but generated vibration is input again to the microphone together with speech signal, causing echo and thus degrading sound quality
Solution Approach 1:
The patent implements feedback by using the microphone to detect the vibration signal that is generated by the actuator and transmitted through the human body. The detected vibration signal is then fed back to the controller, which uses this information to adjust the actuator's output in real-time. This feedback mechanism allows the system to compensate for the echo caused by vibration re-input to the microphone, maintaining reliable audio signal transmission while reducing the harmful echo effect through active cancellation or adjustment.
3Manufacturing precision
If formant enhancement filter is applied to speech signal, then clarity of speech signal is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the formant enhancement filter parameters based on the characteristics of the speech signal. Rather than using a fixed complex filtering system, the controller analyzes the speech signal's formant frequencies and adapts the filter parameters accordingly. This approach improves speech signal clarity by enhancing the relevant formant frequencies while keeping the device complexity manageable through adaptive parameter adjustment rather than fixed complex hardware.
Data Source
AI summary
An apparatus for processing a speech signal is provided. The apparatus includes a communicator comprising communication circuitry configured to transmit and receive data, an actuator comprising actuation circuitry configured to generate vibration and to output a signal, a formant enhancement filter configured to increase a formant of the speech signal, and a controller comprising processing circuitry configured to control the speech signal to be received through the communicator, to estimate at least one formant frequency from the speech signal based on linear predictive coding (LPC), to estimate a bandwidth of the at least one formant frequency, to determine whether the speech signal is a voiced sound or a voiceless sound, to configure the formant enhancement filter based on the at least one formant frequency, the bandwidth of the at least one formant frequency, characteristics of the determined voiced sound or voiceless sound, and signal delivery characteristics of a human body, to apply the formant enhancement filter to the speech signal, and to control the speech signal to which the formant enhancement filter is applied to be output using the actuator through the human body.