Binaural Rendering with IR Synthesis and Drift-Stable Head Tracking
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Solution Overview
Problem
Existing binaural rendering technologies face challenges in accurately replicating the acoustic characteristics of a user's listening environment, particularly due to lengthy and sensitive direct measurement of binaural room impulse responses (BRIRs), and head orientation tracking issues such as IMU drift.
Innovation Solution
Utilizing impulse response (IR) measurements to synthesize binaural room impulse responses, combining them with reference filters through an adaptation process, and anchoring IMU data to a playback device for improved head tracking, incorporating time-of-flight measurements to enhance binaural rendering accuracy and consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement of binaural room impulse responses (BRIRs) is performed to achieve accurate acoustic characteristics, then measurement precision is improved, but measurement time increases and the process becomes more sensitive to environmental factors
Solution Approach 1:
The system performs preliminary measurements of the listening environment to generate acoustic models (such as room impulse responses) in advance. These pre-computed models are then reused during binaural rendering operations, eliminating the need for repeated direct BRIR measurements and significantly reducing measurement time while maintaining accuracy.
Solution Approach 2:
The patent introduces intermediate representations (acoustic models, transfer functions) that mediate between direct environmental measurements and final binaural rendering. These intermediaries capture essential acoustic characteristics without requiring full direct BRIR measurements, reducing both time and sensitivity to environmental variations.
2Measurement precision
If direct measurement of binaural room impulse responses (BRIRs) is performed to achieve accurate acoustic characteristics, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Instead of performing complex direct BRIR measurements, the system creates simplified copies or models of the acoustic environment (room impulse responses, transfer functions). These models replicate the essential acoustic characteristics without requiring the full measurement complexity, reducing device complexity while maintaining measurement precision.
3Adaptability or versatility
If IMU data is used for head tracking to maintain immersive effects, then adaptability is improved, but reliability deteriorates due to IMU drift over time
Solution Approach 1:
The system continuously monitors head position using IMU sensors and feeds this information back to the binaural rendering engine. This feedback loop allows real-time adaptation to head movements while enabling correction of drift through periodic recalibration or fusion with other sensing modalities, maintaining both adaptability and reliability.
Solution Approach 2:
The patent replaces pure mechanical/inertial sensing (IMU) with alternative or complementary methods such as optical tracking, acoustic feedback, or sensor fusion algorithms. This substitution reduces reliance on drift-prone IMU data while maintaining head tracking adaptability, improving overall reliability.
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
Enhances binaural rendering by accurately replicating the acoustic characteristics of the listening environment and maintaining immersive effects over time, regardless of user head position, providing a seamless transition between out-loud and private listening experiences.
Implementation Method 1
one or more time-of-flight measurements of at least one signal propagating from a non-wearable playback device at a first location in a listening environment to the wearable playback device at a second location in the listening environment
Implementation Method 2
Utilizing impulse response (IR) measurements to synthesize binaural room impulse responses
Data Source
AI summary
Example technologies described herein relate to spatial audio on wearable playback devices, such as headphone and earbuds. Such technologies may include forms of binaural rendering of audio, which is played back on the wearable playback devices. These technologies may create or enhance an immersive listening experience which, to the listener, does not sound like you are listening on a wearable device, but are instead listening to a well-tuned, well-place, three-dimensional audio system of loudspeakers in a particular listening environment, such as the listener's actual living room.