Speaker Loudness Processing With Frequency Suppression and Harmonic Shaping

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Solution Overview

Problem

Portable media devices with small speakers face challenges in producing sufficient volume due to physical size restrictions, leading to low output levels and distortion, especially in noisy environments, with existing solutions increasing device bulk or requiring additional gadgets.

Innovation Solution

A system comprising a frequency suppressor, loudness adjuster, and distortion control module that filters out low and high frequencies, calculates and adjusts audio signal gain to approximate human hearing, and induces partial harmonic distortion to increase perceived loudness without increasing distortion or bulk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If the amplitude of the audio signal is increased to compensate for low output levels, then the perceived loudness is improved, but distortion is introduced and battery power consumption increases

Engineering Contradiction:

Improveperceived loudnessVSAvoiddistortion

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The system changes the frequency distribution parameters of the audio signal by attenuating specific frequency bands (particularly mid-range frequencies around 2-5 kHz where human hearing is most sensitive). This allows the overall signal amplitude to be increased for perceived loudness while the distorted components in sensitive frequency ranges are suppressed, reducing the harmful distortion effect

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system converts the naturally occurring distortion that would result from amplitude increase into a beneficial frequency shaping effect. By pre-attenuating the frequency bands most susceptible to perceived distortion, the system allows higher overall amplitudes to be used, effectively converting what would be harmful distortion into an acceptable frequency response modification that enhances loudness

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Illumination intensity

If the amplitude of the audio signal is increased to compensate for low output levels, then the perceived loudness is improved, but battery power consumption increases

Engineering Contradiction:

Improveperceived loudnessVSAvoidbattery power consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The system modifies the frequency parameter distribution of the audio signal to concentrate energy in frequency ranges that are most effective for perceived loudness. By attenuating frequencies that contribute less to perceived loudness and preserving or emphasizing frequencies that are more efficient for human hearing, the system achieves better loudness perception with lower overall power consumption

Inventive Principle:

Principle #35Parameter changes

3Volume of moving object

If small speaker drivers are used to maintain portability, then device size is reduced, but output levels and frequency range reproduction are limited

Engineering Contradiction:

Improvedevice sizeVSAvoidoutput level

Core Design Contradiction:

Volume of moving objectVSIllumination intensity

Solution Approach 1:

The system changes the frequency response parameters of the audio signal to match the capabilities of small speaker drivers. By attenuating frequency bands that small speakers cannot reproduce effectively (particularly low frequencies below 200 Hz and high frequencies above 10 kHz), the system optimizes the signal for the speaker's actual frequency range, maximizing output level within the physical constraints of the small driver

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system applies partial frequency attenuation rather than complete removal, and applies gain compensation in the mid-range frequencies where small speakers perform best. This partial action approach preserves portability while achieving sufficient output levels by focusing energy in the most effective frequency range rather than attempting to reproduce the entire audible spectrum

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS8538042B2System for increasing perceived loudness of speakers

Publication Date: 2013.09.17 DTS INC(US)

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.