In-Car Speech Reinforcement Spatial Audio Alignment
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Solution Overview
Problem
In-car communication systems face challenges in maintaining the naturalness of conversation due to the perception of a speaker's voice originating from multiple spatial locations, causing distraction in occupants, primarily due to delays and relative levels between direct and reproduced sounds.
Innovation Solution
A system and method that determine the spatial location of an audio source and listener, processing audio signals to emit reinforcing signals from multiple audio transducers, ensuring the perceived source is located substantially at the audio source's position, using transfer functions to account for propagation delays and acoustic environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If audio signals are reproduced in audio transducers close to occupants, then communication clarity is improved, but occupants perceive the voice from multiple spatial locations causing distraction
Solution Approach 1:
The audio signal is segmented into multiple components: direct sound from the speaker, reflected sound from various surfaces, and synthesized virtual source sound. Each component is processed separately through different transfer functions to reconstruct the natural spatial perception while maintaining communication clarity.
Solution Approach 2:
A processor acts as an intermediary between the audio transducers and the listener's perception. It synthesizes a virtual audio source signal by combining direct and reflected sound components with appropriate transfer functions, making the reproduced sound appear to originate from the actual speaker's location rather than the transducer locations.
2Productivity
If audio transducers are positioned to reinforce speech signal, then speech reinforcement is achieved, but delay and relative level between direct and reproduced sound degrade naturalness
Solution Approach 1:
The system pre-calculates and stores transfer functions representing acoustic paths from the speaker to the listener through various routes (direct, reflected). These transfer functions are applied in advance to the audio signal to pre-compensate for delays and level differences, ensuring proper temporal alignment when the sound reaches the listener.
Solution Approach 2:
The system dynamically adjusts parameters including time delay, relative level, and frequency response of the reproduced sound based on the transfer functions. By changing these parameters to match the actual acoustic environment, the system achieves speech reinforcement while maintaining natural temporal relationships between direct and reproduced sound.
Data Source
AI summary
A system and method for speech reinforcement may determine the spatial location of an audio source and the spatial location of a listener. An audio signal generated by the audio source may be captured. The spatial location, relative to the listener, of two or more audio transducers that emit a reinforcing audio signal to reinforce the audio signal may be determined. The captured audio signal, responsive to the spatial location of the audio source, the spatial location of the listener and the spatial location of the two or more audio transducers to generate the reinforcing audio signal, such that, when emitted by the two of more audio transducers, the listener perceives a source of the reinforcing audio signal to be spatially located in substantially the spatial location of the audio source thereby reinforcing the audio signal.