Mobile Device Binaural Audio Synthesis via Spatial Filtering
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Solution Overview
Problem
Mobile devices lack the capability to capture binaural audio recordings, which provide a more realistic directional sound experience due to their conventional monophonic microphone configurations, unlike binaural recording systems that mimic human hearing.
Innovation Solution
Implementing a system on mobile devices with multiple microphones to select and process audio signals, applying spatial filtering and transfer functions to generate left-front and right-front audio signals, mimicking the head shadow and pinna effects, thereby enhancing front sound and suppressing back sound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mobile devices use conventional monophonic microphone configurations, then device complexity is reduced and ease of manufacture is improved, but the capability to capture binaural audio recordings and provide realistic directional sound experience deteriorates
Solution Approach 1:
The patent applies the copying principle by creating a virtual binaural recording system that replicates the function of physical binaural microphones through software processing. The system copies the directional sound capture capability of binaural microphones by using multiple existing microphones and applying transfer functions to synthesize the HRTF effect, eliminating the need for specialized binaural microphone hardware while achieving similar auditory results
Solution Approach 2:
The patent applies parameter changes by transforming the audio signals captured by conventional microphones through mathematical operations. By applying transfer functions that modify frequency response, phase, and amplitude parameters of the audio signals, the system converts monophonic recordings into binaural output, changing the acoustic parameters to simulate directional sound perception without altering the physical microphone configuration
2Measurement precision
If mobile devices implement multiple microphones with spatial filtering and transfer functions to generate binaural audio, then directional sound experience and front sound enhancement are improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing transfer functions that represent the acoustic characteristics of the device. These transfer functions, which encode the spatial filtering effects and HRTF transformations, are determined in advance through acoustic measurements or simulations, allowing the complex processing to be reduced to applying pre-computed parameters during actual audio recording, thereby reducing real-time computational complexity
Solution Approach 2:
The patent introduces an intermediary processing layer that acts as a mediator between the simple microphone array and the complex binaural output. The spatial filtering and transfer function application serve as intermediate steps that transform raw microphone signals into directional audio channels, breaking down the complex transformation into manageable intermediate processing stages that can be implemented efficiently
3Reliability
If mobile devices process audio signals to mimic head shadow and pinna effects, then realism of directional sensation is improved, but processing time and computational energy increase
Solution Approach 1:
The patent applies preliminary action by pre-computing the complex transfer functions that embody the head shadow and pinna effects during device manufacturing or initialization. These transfer functions are stored in memory and applied during recording, avoiding the need to perform complex real-time calculations that would consume significant computational energy, while still achieving realistic directional sensation through the pre-baked acoustic transformations
Data Source
AI summary
Audio signals from microphones of a mobile device are received. Each audio signal is generated by a respective microphone of the microphones. First microphones are selected from among the microphones to generate a front audio signal. Second microphones are selected from among the microphones to generate a back audio signal. A first audio signal portion, which is determined based at least in part on the back audio signal, is removed from the front audio signal to generate a modified front audio signal. A second audio signal portion is removed from the modified front audio signal to generate a left-front audio signal. A third audio signal portion is removed from the modified front audio signal to generate a right-front audio signal.