Smartphone Binaural Audio Personalization via BRIR Measurement
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Solution Overview
Problem
Current audio reproduction systems, particularly those using binaural playback over earphones, lack individualization in signal processing, failing to accurately replicate the three-dimensional sonic experience due to the absence of personalized head and environment-specific data, leading to a lack of naturalness and accuracy in sound localization.
Innovation Solution
A method and system utilizing a smartphone with a built-in loudspeaker and microphones to measure binaural room impulse responses (BRIR) by emitting test audio content and determining adjustments for improved playback, allowing for personalized audio reproduction that accounts for individual head and environment characteristics without the need for expensive hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If generalized HRTF and standard dummy heads are used for binaural playback, then the implementation is simple and cost-effective, but individualization (head shadowing, shoulder reflections, pinna effect) is missing leading to reduced naturalness
Solution Approach 1:
The system performs preliminary measurements of the user's actual head and environment characteristics before audio playback using test audio content and microphones positioned at ear locations. These measurements capture individualized head-related transfer functions (HRTF) and room impulse responses (RIR) that are then stored and applied during subsequent audio playback, eliminating the need for complex real-time processing while achieving personalized results
Solution Approach 2:
The system creates a digital copy of the user's acoustic environment and head characteristics by measuring and storing personalized HRTF and RIR data. This copied acoustic signature is then applied to audio content to replicate the user's unique listening experience, replacing generic dummy head models with accurate personal replicas
2Measurement precision
If multiple microphones are positioned at ear locations to measure personalized HRTF, then individualization accuracy is improved, but device complexity and measurement setup complexity increase
Solution Approach 1:
The system uses a universal mobile device (smartphone or tablet) with built-in loudspeaker and microphone that can perform multiple functions: generating test audio content, recording responses at multiple positions, processing measurements, and storing results. This single multi-functional device replaces what would otherwise require separate specialized equipment for audio generation, measurement, processing, and storage
Solution Approach 2:
The mobile device serves itself by using its own built-in loudspeaker to generate test audio and its own microphone to record responses. The device autonomously processes the recorded data to extract HRTF and RIR information, and stores the results in its own memory, eliminating the need for external measurement equipment or complex setup infrastructure
3Ease of operation
If the microphone is positioned in the near-field of the loudspeaker, then the measurement setup is simplified, but the measurement precision may be affected by near-field acoustic effects
Solution Approach 1:
The system performs preliminary near-field measurements to characterize the mobile device's loudspeaker response, then uses this characterization data to correct subsequent far-field HRTF and RIR measurements. By measuring and storing the loudspeaker's near-field acoustic signature first, the system can mathematically compensate for near-field effects in later measurements, combining the ease of near-field setup with the accuracy of far-field measurements
Solution Approach 2:
The system uses feedback by measuring the actual acoustic response at the microphone position and using this information to adjust and correct the HRTF extraction process. The recorded near-field response is fed back into the processing algorithm to compensate for proximity effects, ensuring accurate HRTF measurement even when the microphone is positioned close to the loudspeaker
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 enhances the naturalness and accuracy of three-dimensional sound localization by personalizing audio playback, providing a more immersive experience through the use of smartphones for measuring BRIR, which can correct for smartphone speaker deficiencies and account for earphone characteristics, thereby improving the overall listening experience.
Implementation Method 1
emitting test audio content from the loudspeaker of the mobile device at the first position in the listening environment
Implementation Method 2
receiving the test audio content emitted by the loudspeaker using the at least one microphone at the at least one second location
Data Source
AI summary
The system and method includes positioning a mobile device with a built-in loudspeaker at a first location in a listening environment and at least one microphone at at least one second location in the listening environment; emitting test audio content from the loudspeaker of the mobile device at the first position in the listening environment; receiving the test audio content emitted by the loudspeaker using the at least one microphone at the at least one second location in the listening environment; and, based at least in part on the received test audio content, determining one or more adjustments to be applied to desired audio content before playback by at least one earphone; wherein the first location and the second location are distant from each other so that the at least one microphone is within the near-field of the loudspeaker.