Small-Speaker Loudness Processing With Harmonic Distortion Control
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Solution Overview
Problem
Portable media devices with small speakers face limitations in volume output due to physical size constraints, leading to low output levels and distortion, especially in noisy environments, and existing solutions compromise portability by adding bulk or multiple devices.
Innovation Solution
A system comprising a frequency suppressor, loudness adjuster, and distortion control module that filters out low and high frequencies, calculates and amplifies the audio signal based on human hearing models, and induces partial harmonic distortion to increase perceived loudness without increasing distortion or bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the amplitude of the audio signal is increased to improve perceived loudness, then the loudness is improved, but distortion is introduced and battery power consumption increases
Solution Approach 1:
The patent applies controlled harmonic distortion to increase perceived loudness. By intentionally introducing specific harmonic components through nonlinear processing, the system converts what is traditionally considered a harmful effect (distortion) into a beneficial mechanism for enhancing loudness perception without requiring proportional increases in amplifier power or speaker excursion.
Solution Approach 2:
The system dynamically adjusts audio signal parameters including amplitude, frequency content, and harmonic composition based on the measured loudness of the input signal. By changing these parameters adaptively, the system optimizes perceived loudness while managing distortion levels and power consumption according to the specific audio content and listening conditions.
2Illumination intensity
If external speakers are added to increase output levels, then the loudness is improved, but the portability of the device is compromised
Solution Approach 1:
The patent replaces the mechanical solution of adding external speakers with a digital signal processing approach. By implementing loudness enhancement algorithms that process the audio signal computationally, the system achieves increased perceived output levels without any additional physical hardware, thereby maintaining the portability and compact form factor of the portable media device.
3Volume of moving object
If small speaker drivers are used to maintain device size, then portability is improved, but output levels and frequency range reproduction deteriorate
Solution Approach 1:
The system compensates for the limited output capability of small speaker drivers by dynamically adjusting audio signal parameters. Through loudness-based amplitude adjustment and selective frequency enhancement, the system optimizes the utilization of the small speaker's capabilities to maximize perceived output level within the physical constraints of the portable device form factor.
Data Source
AI summary
A system can be provided for increasing loudness of an audio signal to present a perceived loudness to a listener that is greater than a loudness provided natively by a loudspeaker. The system can include one or more of the following: a frequency suppressor, a loudness adjuster, an equalizer, and a distortion control module. The frequency suppressor can increase headroom in the audio signal by filtering out low and/or high frequencies. The loudness adjuster can calculate a loudness of the audio signal and apply a gain to the audio signal to increase the loudness. The equalizer can further increase headroom by attenuating portions of a passband of the loudspeaker's frequency response. The distortion control module can induce partial harmonic distortion in the audio signal to further increase loudness.