Bass Enhancement Circuit With Selective Low-Frequency Compression
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Solution Overview
Problem
Portable consumer electronic devices with smaller speakers struggle to reproduce low frequency sounds effectively, leading to poor sound quality and increased power consumption when amplifying low frequency components, and existing bass-enhancement methods often compress both low and high frequency signals, reducing dynamic range and wasting energy.
Innovation Solution
An audio processing circuit and compressing circuit that enhance a first frequency part of the audio input signal to produce a bass-enhancement signal, and then reduce the gain of a second frequency part to prevent exceeding speaker thresholds, using a combination of filters and amplifiers to isolate and compress low frequency components while preserving high frequency intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the low frequency component of the audio input signal is amplified to improve bass reproduction, then the sound quality is improved, but the power consumption increases and the speaker may be damaged
Solution Approach 1:
The patent replaces the conventional mechanical approach of directly amplifying low frequency signals with a psychoacoustic processing system. The audio processing circuit generates harmonic frequencies (2f, 3f, 4f, etc.) from the original low frequency signal, and the brain perceives the fundamental frequency through these harmonics. This substitution allows bass enhancement without increasing the physical energy level of the low frequency component, thus avoiding increased power consumption and speaker damage risks.
Solution Approach 2:
The patent changes the frequency parameters of the audio signal by generating harmonic frequencies multiples of the original low frequency signal. Instead of increasing the amplitude of the fundamental frequency, the system transforms the signal into its harmonic components (2f, 3f, 4f, etc.), which the human brain perceives as the original pitch. This parameter transformation achieves bass enhancement while maintaining safe energy levels for the speaker.
2Device complexity
If a band pass filter with low complexity is used to process the audio signal, then the device complexity is reduced, but the transition bandwidth becomes wide and the stop band does not approach zero, causing energy waste
Solution Approach 1:
The patent extracts only the necessary frequency components for bass enhancement by generating harmonic frequencies (2f, 3f, 4f, etc.) from the original low frequency signal. The audio processing circuit selectively creates these specific harmonic components and combines them, rather than using a broad band pass filter. This extraction approach achieves effective bass enhancement with minimal filter complexity while avoiding the energy waste associated with wide transition bands.
3Reliability
If a compressor is used to prevent output signal levels from exceeding the speaker threshold, then the speaker is protected, but both the low frequency and high frequency parts are compressed, reducing the dynamic range and intensity of the high frequency signal
Solution Approach 1:
The patent segments the audio signal processing into distinct frequency components. The audio processing circuit separately generates and processes harmonic frequencies (2f, 3f, 4f, etc.) for bass enhancement, while the original high frequency components remain unaffected. When compression is applied to prevent speaker overload, only the enhanced low frequency harmonic components are compressed, while the original high frequency signal maintains its full dynamic range and intensity, thus avoiding the information loss that would occur with full-signal compression.
Data Source
AI summary
An apparatus for processing an audio input signal is provided and includes an audio processing circuit and an audio compressing circuit. The audio processing circuit receives the audio input signal, and enhances a first frequency part of the audio input signal to output a bass-enhancement signal. The audio compressing circuit is coupled to the audio processing circuit, and reduces a gain of a second frequency part of the bass-enhancement signal to output an audio output signal.