Audio Playback Calibration Using Moving Microphone Frequency Response
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Solution Overview
Problem
Existing media playback systems face challenges in accurately calibrating playback devices to account for the acoustic characteristics of their environment, leading to variations in audio quality across different locations.
Innovation Solution
The system employs a method where the playback device plays calibration sounds that span a specific frequency range, and a computing device captures these sounds at multiple locations using a moving microphone. The captured data is analyzed to determine the frequency response of the playback device, which is then used to adjust the audio processing algorithm to achieve a target frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration sounds are played and captured at multiple locations to determine frequency response, then audio quality consistency across different environments is improved, but the calibration process time and complexity increase
Solution Approach 1:
The system performs preliminary actions by playing calibration sounds across multiple frequency ranges (including ultra-low frequencies below human hearing) before actual audio playback. This preliminary calibration captures acoustic characteristics of the environment in advance, allowing the playback device to pre-adjust its frequency response. The baseline frequency response is established beforehand, enabling faster real-time audio adjustment without repeated multi-location measurements.
Solution Approach 2:
The system uses partial action by focusing calibration measurements on specific critical frequency ranges (particularly ultra-low frequencies below 20 Hz that are imperceptible to humans) rather than measuring all audible frequencies at multiple locations. This selective approach captures the most impactful acoustic characteristics while reducing the number of measurement points needed, thereby shortening calibration time while maintaining audio quality consistency.
2Measurement precision
If calibration sounds include ultra-low frequencies below human hearing range, then acoustic characteristics of environment are more accurately captured, but the complexity of the calibration system increases
Solution Approach 1:
The playback device performs self-calibration by generating its own calibration sounds and capturing them with its built-in microphone. The device autonomously determines its baseline frequency response in its actual playback environment without requiring external calibration equipment or expert intervention. This self-service approach simplifies the system while enabling accurate capture of ultra-low frequency acoustic characteristics.
Solution Approach 2:
The playback device's built-in microphone serves multiple functions: it acts as both a standard audio input device for normal operation and as a calibration measurement microphone for frequency response analysis. The same speaker drivers that play audible music also generate ultra-low frequency calibration tones. This multi-functionality eliminates the need for separate calibration equipment, reducing system complexity while maintaining measurement accuracy.
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 allows for precise calibration of playback devices, ensuring consistent audio quality across different environments by accurately accounting for the acoustic characteristics of each location.
Implementation Method 1
the playback device plays one or more calibration sounds that span a frequency range
Implementation Method 2
a computing device captures these sounds at multiple locations using a moving microphone
Implementation Method 3
The captured data is analyzed to determine the frequency response of the playback device
Implementation Method 4
which is then used to adjust the audio processing algorithm to achieve a target frequency response
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.