HRTF Calibration Using Depth Cameras and Base Stations
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Solution Overview
Problem
Conventional methods for determining head-related transfer functions (HRTFs) are inefficient in terms of time and hardware resources, requiring complex infrastructure and taking over an hour to generate high-quality surround sound experiences due to the need for multiple HRTFs at various speaker locations.
Innovation Solution
A system and method using base stations with a head-mounted display (HMD) and depth cameras to determine HRTFs by emitting test sounds and analyzing audio samples, allowing for efficient calibration of HRTFs in both static and dynamic modes, reducing the need for extensive sound dampening chambers and speaker arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods use sound dampening chambers and multiple speaker arrays to determine HRTFs, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses virtual reality environments to create virtual copies of acoustic spaces and sound sources, replacing the need for physical sound dampening chambers and multiple speaker arrays. The HRTF measurement is performed in a virtual environment that replicates real-world acoustic conditions without requiring complex physical infrastructure.
Solution Approach 2:
The patent replaces the mechanical/acoustic measurement system (physical speakers, sound dampening chambers) with a computational system that uses virtual reality rendering and digital signal processing to determine HRTFs, significantly reducing hardware complexity while maintaining measurement precision.
2Measurement precision
If multiple HRTFs are determined for many different speaker locations to reduce error, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent implements dynamic HRTF determination where the virtual speaker locations and measurement parameters are adaptively adjusted during the calibration process. The system can determine HRTFs for multiple locations efficiently by leveraging the virtual environment's ability to rapidly change acoustic conditions without physical reconfiguration, reducing calibration time while maintaining accuracy.
Solution Approach 2:
The patent performs preliminary HRTF measurements at key locations in the virtual environment, then uses interpolation and computational methods to derive HRTFs for intermediate locations, reducing the total number of direct measurements needed while maintaining overall measurement precision.
3Measurement precision
If conventional methods use extensive speaker arrays and sound dampening chambers, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent creates a universal virtual measurement environment that can determine HRTFs for multiple speaker locations and configurations within a single setup. The virtual reality system serves multiple functions: it acts as the measurement environment, generates test signals, processes audio samples, and determines HRTFs, eliminating the need for separate physical infrastructure for each measurement condition and significantly improving productivity.
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 significantly reduces the time and resources required for HRTF determination, enabling efficient generation of high-quality surround sound experiences while allowing for on-the-fly recalibration during virtual or augmented reality applications.
Implementation Method 1
A depth camera assembly determines depth information describing a position of the HMD in the local area relative to the locations of the base stations
Implementation Method 2
each base station includes a speaker configured to emit a test sound in accordance with calibration instructions
Implementation Method 3
The microphone generates a respective audio sample from the test sound emitted by the speaker of each base station
Implementation Method 4
The HRTF for a particular source location relative to a person is unique to each ear of the person (and is unique to the person) due to the person's anatomy (e.g., ear shape, shoulders, etc.,) that affects the sound as it travels to the person's ears
Data Source
AI summary
A system including base stations determines head-related transfer functions (HRTFs) for a user. Each base station is located at a distinct location within a local area and includes a speaker configured to emit a test sound in accordance with calibration instructions. A depth camera assembly determines depth information describing a position of a head-mounted display (HMD) in the local area relative to the locations of the base stations. A microphone is placed in an ear canal of a user wearing the HMD, and generates a respective audio sample from the test sound emitted by the speaker of each base station. A controller determines the relative position of the HMD using the depth information, generates the calibration instructions based on the relative position of the HMD, and determines the HRTFs based on the audio samples.