Audio Playback Synchronization via Calibration Sound Analysis
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Solution Overview
Problem
Conventional smart speaker systems face synchronization issues due to unsynchronized clocks and latency differences, leading to an uneven audio experience for listeners, particularly in stereophonic setups where sound arrival times and amplitudes vary based on speaker distances from the listener.
Innovation Solution
A computerized microphone-equipped audio playback device system that calculates and adjusts playback delays and gains based on listener position propagation differentials, derived from calibration sound data across multiple devices, ensuring synchronized audio arrival and optimal listening experience without requiring synchronized clocks or explicit speaker geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional smart speaker systems play audio without synchronization adjustments, then the system is simple to operate, but the audio arrival times and amplitudes vary based on speaker distances from the listener, creating an uneven audio experience
Solution Approach 1:
The system performs preliminary calibration by playing calibration sounds at known times and recording their arrival times at the listener position. This preliminary measurement allows the system to calculate propagation differentials and pre-compute playback delay adjustments, so that during actual audio playback, the devices can automatically synchronize without requiring complex real-time coordination or manual configuration.
Solution Approach 2:
The system uses feedback from the calibration process where devices record the actual arrival times of calibration sounds and use this information to compute and adjust playback delays. This feedback mechanism enables the system to automatically compensate for variations in speaker distances and clock synchronization issues, achieving precise audio synchronization without requiring complex manual setup.
2Reliability
If the system calculates and adjusts playback delays based on listener position propagation differentials, then audio synchronization is improved, but the device complexity increases due to calibration processes and processing requirements
Solution Approach 1:
Each audio playback device performs self-calibration by autonomously playing calibration sounds, recording their arrival times at the listener position, and computing its own propagation differentials. The system uses its own internal resources (microphone, processor, clock) to complete the calibration process without requiring external calibration equipment or manual measurement, thereby reducing the operational complexity while maintaining reliable synchronization.
Solution Approach 2:
The calibration process is performed as a preliminary one-time setup that establishes propagation differentials and playback delay adjustments before actual audio playback begins. By completing these calculations and adjustments in advance, the system avoids the need for complex real-time coordination during music playback, reducing the operational complexity while ensuring reliable synchronization.
3Manufacturing precision
If the system uses calibration sounds to determine propagation differentials, then audio arrival synchronization is achieved, but the calibration process requires multiple data exchanges between devices
Solution Approach 1:
The calibration process uses periodic action by having devices play calibration sounds at specific intervals and record arrivals at predetermined times. This structured periodic measurement approach allows the system to efficiently collect the necessary data to compute propagation differentials without requiring continuous or excessively frequent calibration signals, thereby minimizing the time lost during calibration while achieving precise synchronization.
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
The system effectively synchronizes audio playback across multiple speakers, enhancing the stereophonic experience by compensating for latency and amplitude differences, thus providing a consistent and enhanced audio experience at the listener's position.
Implementation Method 1
receive data indicative of an arrival time of a first calibration sound at the processor
Implementation Method 2
play the digital audio on a speaker
Data Source
AI summary
An audio system including a first microphone-equipped playback device and a second microphone-equipped playback device. The audio system is configured to synchronize playing of audio to a listener position by receiving by the first microphone-equipped playback device an audio stream, and playing the audio stream on a speaker of the first microphone-equipped playback device, in accordance with a playback delay Δt. The playback delay Δt is in accordance with a first calibration sound originating at the listening position, a second calibration sound originating at the second microphone-equipped playback device, and a third calibration sound originating at the first microphone-equipped playback device.