Audio Transmission System with Virtual Sound Source Positioning
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Solution Overview
Problem
Conventional audio transmission systems in communication conferences struggle to create a high level of presence by accurately identifying and positioning sound sources, leading to difficulties in distinguishing speakers and maintaining consistent sound volumes due to varying participant audio levels and microphone distances.
Innovation Solution
An audio transmission system that employs a microphone array and a loudspeaker array, along with a position detection device, to set the directivity characteristic of microphones and loudspeakers, forming a virtual sound source at the detected position, allowing for precise audio reproduction and enhanced presence in the sound field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If audio data is reproduced from all loudspeakers at equal sound volume and phase, then the system is simple to operate, but speaker identification becomes difficult and sound field presence is reduced
Solution Approach 1:
The patent segments the audio reproduction by controlling each loudspeaker independently based on detected sound source position. Instead of uniform reproduction from all loudspeakers, the system divides the reproduction task among specific loudspeakers according to the spatial location of the speaker, enabling both simple operation and accurate speaker identification.
Solution Approach 2:
The patent introduces position detection information as an intermediary between the microphone input and loudspeaker output. This intermediary data enables the system to maintain simple operation while achieving accurate speaker identification by mediating the audio reproduction process through position-based control.
2Stability of the object's composition
If sound volume of loudspeaker is fixed, then the system is stable, but sound volume fluctuates significantly when multiple participants speak due to differences in audio sound volume and microphone distance
Solution Approach 1:
The patent applies dynamics by making the loudspeaker sound volume adjustable rather than fixed. The system dynamically adjusts the sound volume of each loudspeaker based on the detected position of the sound source and the input level from corresponding microphones, enabling consistent sound volume reproduction even when multiple participants speak simultaneously.
3Extent of automation
If switches are provided for each microphone to select audio data with highest input level, then speaker selection is automated, but accurate audio data cannot be transmitted when multiple speakers speak simultaneously due to switching time requirements
Solution Approach 1:
The patent segments the audio data transmission by assigning different audio data from different microphones to different loudspeakers based on sound source position. Instead of using a single switch to select one microphone's audio data, the system divides the reproduction task among multiple loudspeakers, each receiving audio data from the microphone closest to the sound source in its respective direction, enabling reliable simultaneous transmission of multiple speakers' audio.
4Device complexity
If only sound volumes of loudspeakers are controlled based on position information, then the system configuration is simple, but a sound field with high level of presence cannot be realized
Solution Approach 1:
The patent applies local quality by controlling not only the sound volume but also the phase of each loudspeaker based on the detected sound source position. This enables the system to maintain simple configuration while achieving high-level presence through position-based phase control that creates accurate spatial audio reproduction.
Data Source
AI summary
In an audio transmission system, a control section of a communication conference device emits measurement sound waves from a loudspeaker array to a terminal unit and measures the time until a response is received, thereby detecting the position of the terminal unit. The control section sets directivity characteristics so that microphone sensitivity of the microphone array is brought to point to the position of the terminal unit, and sends the collected audio to another communication conference device. In a communication conference device on the reception side, the directivity characteristic of the loudspeaker array is set so that the received audio appears as if it was emitted from the position of the terminal unit on the transmission side.