Audio Signal Head Tracking System
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Solution Overview
Problem
Current head tracking systems for surround sound reproduction via headphones require significant hardware, failing to accurately simulate spatial orientation due to lack of amplitude, phase shifting, and frequency filtering effects, leading to a diminished surround sound experience.
Innovation Solution
A tracking system utilizing non-audible detection signals in the audible frequency range, transmitted between transmitters and detectors, determines the orientation or position of a movable object based on propagation time, leveraging existing audio system components like loudspeakers and microphones to reduce hardware requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If head tracking systems use measurement devices and transmitters to track head movement, then the spatial orientation can be determined, but the hardware complexity and cost increase significantly
Solution Approach 1:
The patent makes existing audio system components (loudspeakers and microphones) serve dual functions: loudspeakers generate both audio output and ultrasonic detection signals, while microphones serve both audio input and position detection. This eliminates the need for separate tracking hardware, resolving the contradiction between measurement capability and hardware complexity
Solution Approach 2:
The audio system's own components are used to perform the tracking function. The system uses its existing loudspeakers to emit detection signals and its existing microphones to receive them, allowing the system to track head position using its own resources without requiring additional dedicated tracking hardware
2Device complexity
If surround sound is reproduced through headphones without amplitude and phase shifting effects, then the hardware is simplified, but the listener cannot locate sound sources in space
Solution Approach 1:
The patent replaces the need for complex acoustic field manipulation (amplitude and phase shifting) with a direct mechanical/physical measurement approach: using ultrasonic time-of-flight measurements to directly calculate head position and orientation, then applying appropriate spatial processing to the audio signals. This maintains spatial accuracy while keeping the hardware simple
Solution Approach 2:
The patent introduces ultrasonic detection signals as an intermediary mechanism. These high-frequency signals provide precise positional information about head movement, which then informs the spatial processing of the main audio signals. This intermediary allows accurate spatial localization without requiring complex acoustic field manipulation in the audible range
3Difficulty of detecting and measuring
If detection signals are transmitted at audible levels, then the transmission can be detected by human ears, but it disturbs the audio perception and listening experience
Solution Approach 1:
The patent changes the frequency parameter of the detection signals to the ultrasonic range (above 20 kHz), which is inaudible to humans. This allows the detection signals to be transmitted and received for tracking purposes without being perceived by the listener, thus eliminating disturbance to the audio experience while maintaining detectability by the microphone system
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 enhances the accuracy of spatial sound simulation for headphones by using audio signals below the threshold of human hearing, allowing for reduced hardware costs and improved surround sound experience without disturbing the audio perception.
Implementation Method 1
A signal generator of the tracking system generates a non-audible detection signal in an audible frequency range
Implementation Method 2
A processor may determine an orientation or position of the moveable object based on the transmission time between the transmitting device and the detection device
Data Source
AI summary
A tracking system may determine the orientation or position of a movable object. The tracking system includes a signal generator that generates a non-audible detection signal in an audible frequency range. A transmitting device transmits the detection signal to a detection device. The transmitting device or the detection device may be positioned on the movable object, and the other may be positioned at a remote location. A processor may determine an orientation or position of the moveable object based on the transmission time between the transmitting device and the detection device.