Audio Playback Calibration Using Moving Microphone Frequency Response
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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 data at multiple points and adjust audio processing algorithms accordingly, while minimizing interference between multiple devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration sounds are played to determine frequency response, then measurement precision is improved, but device complexity increases due to multiple components and processing steps
Solution Approach 1:
The calibration sound is divided into multiple distinct components (sine sweep, pink noise, white noise, guard bands) that serve specific functions. This segmentation allows each component to contribute to different aspects of the frequency response measurement, improving overall measurement precision while organizing the complexity into manageable, functional segments
Solution Approach 2:
A transfer function is introduced as an intermediary element that characterizes the relationship between the playback device and measurement microphone. This transfer function serves as a mediator that captures the acoustic characteristics of the environment and device interaction, enabling accurate frequency response determination without requiring direct complex measurements
2Productivity
If multiple playback devices are calibrated simultaneously, then productivity is improved, but measurement precision deteriorates due to interference between devices
Solution Approach 1:
The calibration process uses periodic playback of distinct calibration sound components across multiple devices. By systematically cycling through different sound components (sine sweep, noise types, guard bands) in a controlled sequence, multiple devices can be calibrated simultaneously while the periodic structure allows for interference management and signal differentiation
Solution Approach 2:
The calibration process maintains continuous useful action by playing calibration sounds across the entire frequency range without interruption. The guard bands act as continuous separators that prevent interference while the calibration sounds continuously probe the frequency response, ensuring uninterrupted measurement across all devices
3Measurement precision
If guard bands are included in calibration sounds, then measurement precision is improved by preventing interference, but loss of information increases due to reduced energy in usable frequency ranges
Solution Approach 1:
Guard bands are placed in advance at the boundaries of calibration frequency ranges to preemptively prevent interference from overlapping signals. This preliminary anti-action blocks potential interference before it can corrupt the measurement, ensuring precision while the energy loss is confined to these predetermined, non-critical frequency regions
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 enables precise calibration of playback devices, ensuring consistent audio quality across environments by accounting for acoustic characteristics, even in multi-device setups, thereby enhancing the listening experience.
Implementation Method 1
a playback device to play one or more calibration sounds that span a wide frequency range
Implementation Method 2
use a moving microphone to capture data at multiple points
Implementation Method 3
determine the frequency response of the playback device
Implementation Method 4
adjust audio processing algorithms accordingly, while minimizing interference between multiple devices
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.