Micro-Speaker Equalization for Free-Space Frequency Response
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Solution Overview
Problem
Handheld devices with micro-speakers experience reduced sound volume and distorted low-frequency output when held in free-space due to finite baffle size, leading to uneven frequency response compared to when placed on a surface.
Innovation Solution
A system with a detection device and processor that adjusts audio signals based on the device's position, applying a compensating function to boost low-frequency signals when held in free-space and using a ported enclosure tuned to a different resonance frequency to enhance low-frequency output without distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a handheld device is held in free-space, then the device is portable and easy to operate, but the baffle size is finite causing reduced sound volume and distorted low-frequency output
Solution Approach 1:
The patent applies dynamics by making the audio output characteristics changeable based on the device's operational state. The system dynamically adjusts the frequency response and sound pressure level depending on whether the device is held in free-space or placed on a surface, allowing optimal audio performance for each state while maintaining portability throughout
Solution Approach 2:
The patent changes physical parameters of the audio system to compensate for the finite baffle effect. By adjusting the frequency response parameters and applying equalization filters, the system compensates for the 6 dB loss at low frequencies when held in free-space, maintaining uniform frequency response across different operating conditions
2Difficulty of detecting and measuring
If the baffle size is increased to improve low-frequency output, then the frequency response becomes more uniform, but the device size increases beyond ergonomic constraints
Solution Approach 1:
The patent replaces the mechanical solution (increasing physical baffle size) with an electronic/acoustic solution (frequency response adjustment and equalization). Instead of physically enlarging the device to achieve infinite baffle characteristics, the system uses digital signal processing to compensate for the finite baffle effect, maintaining compact size while achieving uniform frequency response
Solution Approach 2:
The patent changes the acoustic parameters of the audio output to simulate the effect of a larger baffle. By adjusting frequency response parameters and applying state-dependent equalization, the system achieves the acoustic benefits of a large baffle without the corresponding increase in physical device dimensions
3Difficulty of detecting and measuring
If a ported enclosure is used to enhance low-frequency output, then the sound pressure increases, but distortion occurs when the speaker displacement exceeds the rated maximum
Solution Approach 1:
The patent applies feedback by continuously monitoring the audio output characteristics and adjusting the frequency response accordingly. The system uses feedback from the detected operating state (held or placed) to dynamically adjust the equalization parameters, ensuring optimal low-frequency output while preventing distortion by staying within the speaker's rated displacement limits
Solution Approach 2:
The patent makes the audio system dynamic by adjusting the frequency response and sound pressure level based on the detected operating state. When the device is placed on a surface, the system can safely increase low-frequency output; when held in free-space, the system adjusts parameters to prevent excessive speaker displacement and distortion, creating an adaptive audio system
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
The system provides a flat frequency response and improved sound quality across various applications, maintaining consistent audio performance whether the device is held in free-space or placed on a surface with reduced distortion at low frequencies.
Implementation Method 1
a ported enclosure configured to house a micro-speaker. The ported enclosure includes an enclosure comprising a port, where the enclosure is tuned to a first resonance frequency that is different from a second resonance frequency associated with the micro-speaker
Data Source
AI summary
One embodiment of the present invention sets forth a system that includes a detection device and a processor. The detection device is configured to sense that a handheld device has not been placed on or near a surface. In response to sensing that the handheld device has not been placed on or near a surface, the detection device is configured to transmit an indicator to the processor. The processor is configured to receive a first audio signal, and determine that the handheld device has not been placed on or near a surface by receiving the indicator from the detection device. In response to determining that the handheld device has not been placed on or near a surface, the processor is further configured to apply a compensating function to the first audio signal to generate a second audio signal, and transmit the second audio signal to a speaker.