Playback Device Calibration with Swept Audio and Moving Microphone
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Solution Overview
Problem
Existing audio playback systems face challenges in accurately calibrating playback devices to account for environmental acoustic characteristics, leading to inconsistent audio quality across different locations within a given space, especially when multiple devices are synchronized.
Innovation Solution
The system employs calibration sounds that span a wide frequency range, including noise and swept components, to determine the frequency response of playback devices within their environments, using a moving microphone to capture these sounds and adjust audio processing algorithms to achieve a target frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration sounds are played to determine frequency response, then audio quality consistency is improved, but environmental noise interference worsens measurement accuracy
Solution Approach 1:
The patent converts environmental noise from a harmful factor into a useful calibration signal by using swept-frequency sounds that deliberately sweep through the frequency range. The system plays calibration sounds at multiple frequencies and uses the known swept pattern to distinguish calibration signals from environmental noise, effectively converting the noisy environment into part of the calibration process rather than treating it as pure interference.
Solution Approach 2:
The calibration process uses periodic swept-frequency sounds that cycle through the frequency range repeatedly. By playing calibration sounds at multiple frequencies in a periodic manner and comparing responses across cycles, the system can distinguish between consistent calibration signal responses and random environmental noise, improving measurement precision despite noisy conditions.
2Area of stationary object
If multiple playback devices are synchronized, then audio coverage is improved, but interference between devices worsens frequency response consistency
Solution Approach 1:
The patent segments the calibration process by having each playback device calibrated individually through sequential processing. The system plays calibration sounds from one device at a time, measures its frequency response independently, and adjusts its parameters before moving to the next device. This segmentation eliminates interference between devices during measurement while still enabling synchronized multi-device operation afterward.
Solution Approach 2:
The system performs preliminary calibration of each playback device individually before synchronized operation. By pre-adjusting frequency response parameters for each device based on its specific environmental characteristics and position, the system ensures that when devices operate together, they maintain consistent frequency responses without interfering with each other's measurements.
3Ease of operation
If calibration is performed at fixed location, then measurement simplicity is improved, but spatial audio consistency worsens across different positions
Solution Approach 1:
The patent extends calibration from a single fixed location to multiple spatial dimensions by placing microphones at various positions throughout the room. The system measures frequency response at multiple locations and uses this multi-dimensional data to optimize playback parameters, ensuring consistent audio quality across the entire space rather than just at one calibration point.
Solution Approach 2:
The system performs preliminary measurements at multiple spatial positions before final parameter optimization. By collecting frequency response data from various locations in advance, the system can compute optimal playback parameters that ensure spatial consistency, maintaining both operational simplicity and audio consistency across different listening positions.
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 approach ensures consistent and optimized audio playback by characterizing the acoustic environment and adjusting the playback device's frequency response, enhancing audio quality and reducing interference between multiple devices.
Implementation Method 1
capturing, via a moving microphone of the computing device, one or more calibration sounds played by the playback device... using the one or more sections of the data to determine a frequency response of the playback device over the calibration frequency range. The frequency response of the playback device characterizes audio playback by the playback device as influenced by acoustic characteristics of an environment of the playback device
Data Source
AI summary
Example techniques facilitate calibration of a playback device. An example implementation involves a computing device capturing, via a microphone, data representing multiple iterations of a calibration sound as played by a playback device. The computing device identifies multiple sections within the captured data. Two or more sections represent respective iterations of the calibration sound as played by the playback device. Based on the multiple identified sections, the computing device determines a frequency response of the playback device, the frequency response of the playback device representing audio output by the playback device and acoustic characteristics of an environment around the playback device. Based on the frequency response of the playback device and a target frequency response, the computing device determines one or more parameters of an audio processing algorithm and sends, to the playback device, the one or more parameters of the audio processing algorithm.