Harmonic Bass Generation for Small Speaker Audio Systems
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Solution Overview
Problem
Conventional loudspeakers face challenges in reproducing low-frequency sounds due to size and cost constraints, leading to inadequate bass performance, which affects the overall sound quality and balance of music playback.
Innovation Solution
A method and system for generating harmonics using a harmonics generator with a gain controller to adjust the amplitude of harmonic components, allowing for the perception of lower pitches than the speaker can reproduce through the 'missing fundamental' phenomenon, by extracting lower frequency ranges and adding harmonics back to the input signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of loudspeaker drivers is reduced to meet portability requirements, then the device becomes more compact and portable, but the bass performance deteriorates due to insufficient low-frequency reproduction capability
Solution Approach 1:
The patent replaces the mechanical approach of using large physical drivers for bass reproduction with a signal processing approach. A harmonics generator processes the audio signal to create harmonic components that simulate the perception of low frequencies through the 'missing fundamental' phenomenon, allowing small speakers to deliver perceived bass without requiring large drivers
Solution Approach 2:
The patent changes the frequency domain parameters of the audio signal by generating harmonic components at specific frequency ratios relative to the fundamental frequency. This allows the system to create the perception of low frequencies (e.g., 30 Hz) by generating harmonics at higher frequencies (e.g., 60 Hz, 90 Hz, 120 Hz) that small speakers can reproduce effectively
2Reliability
If equalization is used to increase bass amplitude, then the bass performance is improved, but the loudspeaker membrane experiences excessive movement causing distortion or damage
Solution Approach 1:
The patent substitutes the mechanical solution of boosting bass amplitude through equalization with a signal processing solution. By generating harmonic components that create the perception of low frequencies, the system avoids the need for large membrane excursions that would cause distortion or damage while still delivering perceived bass performance
3Reliability
If large magnets and physical size are used in low-frequency drivers to improve bass reproduction, then the bass performance is improved, but the cost and device size increase significantly
Solution Approach 1:
The patent replaces the expensive and large mechanical low-frequency drivers with a digital signal processing approach. The harmonics generator creates the perception of bass through signal manipulation, eliminating the need for large magnets and physically large drivers, thereby reducing both cost and device size while maintaining bass reproduction capability
Solution Approach 2:
The patent creates a perceptual copy of the bass experience by generating harmonic components that simulate the acoustic characteristics of low frequencies. Instead of reproducing the actual low-frequency sound waves that require large drivers, the system generates higher-frequency harmonics that the human ear perceives as the fundamental bass frequency, achieving the same auditory effect with much smaller hardware
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
This approach enhances bass performance without causing distortion, allowing listeners to perceive lower pitches than the speaker can physically reproduce, thereby improving sound quality and balance across different frequency regions.
Implementation Method 1
According to the so-called missing fundamental phenomenon, the pitch of the fundamental from which the harmonics are generated can then be perceived if the listener hears two or more consecutive harmonics of the fundamental frequency.
Data Source
AI summary
A method and corresponding system for generating harmonics from an input signal having an input frequency uses a harmonics generator having an associated gain controller generating adjustable gain control factors, controlling the amplitude of harmonic components. The method includes generating a series of harmonic components in a process including adjustment of relative balances between at least three harmonic components of different orders, the balances being independently adjustable by controlling at least two gain control factors. Each gain control factor is adjusted based on a frequency dependent measure of the input signal or signal derived therefrom, of the frequency dependent measure of the input signal and/or derived signal unique for the corresponding gain control factor. An output signal is created including the harmonic components according to the balances as controlled by the at least two gain control factors, wherein the balances between the harmonic components depend on the input frequency.