Virtual Height Speaker Calibration Using Mobile Device Microphone
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Solution Overview
Problem
Current spatial audio systems, particularly in home environments, face challenges due to the lack of overhead or height speakers, which limits the full exploitation of spatial audio content, as equipment costs and installation complexity are barriers to implementing advanced audio technologies like Dolby Atmos.
Innovation Solution
The implementation of an adaptive audio system using upward-firing speakers with virtual height filtering, which simulates overhead sound by reflecting sound off the ceiling, and a mobile device-based calibration method to adjust acoustic power ratios between top-firing and front-firing speakers, enabling effective reproduction of height cues without the need for ceiling-mounted speakers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ceiling-mounted height speakers are used to reproduce overhead sound objects, then spatial audio quality is improved, but equipment cost and installation complexity increase
Solution Approach 1:
Instead of mounting speakers on the ceiling to play sound downward, the patent inverts the approach by placing speakers on the floor and playing sound upward. The upward-firing drivers direct acoustic energy at the ceiling, which reflects the sound back down to create virtual overhead sound objects. This inversion resolves the contradiction by achieving spatial audio quality without requiring ceiling installation.
Solution Approach 2:
The patent creates virtual copies of overhead speakers using acoustic reflection. By directing sound upward at the ceiling and capturing the reflected sound, the system generates virtual sound objects that appear to originate from overhead positions. This copying approach achieves the spatial audio effect of ceiling-mounted speakers using floor-based equipment.
2Ease of manufacture
If upward-firing speakers are used to simulate overhead sound, then equipment cost is reduced, but acoustic power ratio calibration becomes more complex
Solution Approach 1:
The calibration system uses the user's own mobile device (smartphone or tablet) as the measurement microphone, eliminating the need for specialized calibration equipment. The mobile device's built-in microphone captures acoustic test signals, and the device's processor performs the calibration calculations. This self-service approach reduces equipment cost while managing calibration complexity through software automation.
Solution Approach 2:
The patent makes the mobile device serve multiple functions: it acts as the audio source playing test signals, the measurement instrument capturing acoustic responses, and the processing unit performing calibration calculations. This multi-functionality reduces the need for dedicated calibration equipment, lowering overall system cost while the software handles the complexity of acoustic power ratio measurements.
3Ease of manufacture
If mobile device calibration is used to adjust acoustic power ratios, then calibration equipment cost is reduced, but measurement precision may be compromised
Solution Approach 1:
The calibration process uses feedback from the mobile device's microphone to measure the actual acoustic power of both front-firing and upward-firing speakers. The system plays test signals through each speaker type, captures the acoustic response with the microphone, and uses this feedback to calculate and adjust acoustic power ratios. This feedback loop ensures measurement accuracy despite using consumer-grade mobile device components.
Solution Approach 2:
The patent applies preliminary equalization filters to the test signals before playback to compensate for the frequency response characteristics of the mobile device's speaker and microphone. This preliminary action pre-corrects for potential measurement errors, ensuring that the acoustic power measurements taken by the mobile device remain accurate despite the non-professional-grade components.
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 solution allows for immersive 3D audio experiences in home settings by simulating overhead sound using upward-firing speakers and mobile device calibration, overcoming equipment and installation constraints, thereby enhancing audio immersion and artistic control.
Implementation Method 1
upward-firing speakers with virtual height filtering, which simulates overhead sound by reflecting sound off the ceiling
Data Source
AI summary
At least part of a speaker calibration process, such as a process of adjusting the gain of a top-firing speaker of a virtual height speaker system to compensate for ceiling height and/or ceiling acoustic reflectivity, may be done using a mobile device (a smart phone, a tablet, etc.) running a mobile device application on a mobile operating system (iOS, Android, etc.). An un-calibrated or minimally calibrated microphone, of the type typically found in mobile devices such as smart phones and tablets, may be used to provide input for such speaker calibration processes.