Audio Processing Device Spherical Harmonics Headphone Drive Signal
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Solution Overview
Problem
Ambisonics technology requires a large speaker array and has a limited sound reproduction space, making it impractical for home use and difficult to provide desired audio effects to all audience members in large spaces like movie theaters, while combining with binaural reproduction technology increases operation and memory usage.
Innovation Solution
An audio processing device that generates a vector using head-related transfer functions via spherical harmonic transform, synthesizing an input signal in the time-frequency domain to create a headphone drive signal, reducing the need for a large speaker array and optimizing memory usage by performing convolution in the spherical harmonic domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Ambisonics combines with binaural reproduction technology, then spatial audio reproduction capability is improved, but operation amount and memory usage increase
Solution Approach 1:
The patent pre-calculates and stores head-related transfer function values in a lookup table before runtime. During actual audio reproduction, the system only needs to retrieve pre-computed values based on current head orientation angles, avoiding real-time convolution operations. This preliminary preparation significantly reduces operational complexity while maintaining high-fidelity spatial audio reproduction
Solution Approach 2:
The patent creates a simplified computational model by copying essential characteristics of head-related transfer functions into a discrete lookup table structure. Instead of performing complete convolution operations, the system uses tabulated values that replicate the key spatial filtering effects, reducing computational burden while preserving the core binaural reproduction functionality
2Measurement precision
If Ambisonics uses a large speaker array to increase spatial resolution, then sound reproduction quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical speaker array system with a computational approach using head-related transfer functions and lookup tables. Instead of physically distributing multiple speakers to achieve spatial resolution, the system uses pre-computed acoustic transfer functions that mathematically simulate the effects of a large speaker array, achieving high spatial resolution through signal processing rather than physical expansion
Solution Approach 2:
The patent transforms the physical parameter of speaker quantity into computational parameters of head-related transfer function values stored in lookup tables. By changing from a mechanical expansion approach (adding speakers) to a computational approach (storing pre-calculated values), the system achieves high spatial resolution without increasing physical device complexity
3Device complexity
If Ambisonics limits the number of microphones and speakers, then device simplicity is improved, but adaptability to different recording and reproducing systems deteriorates
Solution Approach 1:
The patent creates a universal audio processing framework that can handle arbitrary microphone arrays and speaker configurations through the use of Ambisonics encoding/decoding combined with binaural reproduction. The system uses spherical harmonic transforms and head-related transfer functions that are independent of specific hardware configurations, allowing the same processing pipeline to work with different numbers and arrangements of microphones and speakers
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
Enables efficient sound reproduction by reducing operation and memory requirements, allowing for the same Ambisonics effects with a headphone system, improving spatial audio reproduction without the need for a large speaker array and expanding the sound reproduction space.
Implementation Method 1
a matrix generation unit which generates a vector for each time-frequency with a head-related transfer function obtained by spherical harmonic transform by spherical harmonics as an element
Data Source
AI summary
Provided is an audio processing device and method, in which sound can be more efficiently reproduced. An audio processing device includes a matrix generation unit which generates a vector for each time-frequency with a head-related transfer function obtained by spherical harmonic transform by spherical harmonics as an element by using only the element corresponding to a degree of the spherical harmonics determined for the time-frequency or on the basis of the element common to all users and the element dependent on an individual user, and a head-related transfer function synthesis unit which generates a headphone drive signal of a time-frequency domain by synthesizing an input signal of a spherical harmonic domain and the generated vector.