Bluetooth Audio Volume Calibration Using SPL Lookup Tables
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Solution Overview
Problem
In short-range wireless communication systems, particularly in multi-channel surround sound systems, there is a challenge in calibrating and controlling the sound pressure level (SPL) of output volumes across devices, which affects audio data output consistency and synchronization, especially when using Bluetooth technology with varying electro-acoustic characteristics.
Innovation Solution
A method and apparatus where a control device transmits signals to configure audio data output volumes as reference values, uses test streams for calibration, and measures audio data outputs based on sound pressure levels (SPL) to ensure all devices in the system produce a consistent SPL, employing a pre-configured table for mapping audio data output volume values to SPL values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Bluetooth devices are connected using traditional connection methods, then device connectivity is established, but the complexity of connection management and control increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring audio output volume values in a lookup table before actual audio playback. The control device stores multiple volume values corresponding to different SPL requirements, so when calibration is needed, the device can directly retrieve and apply the appropriate pre-configured value without complex real-time calculations or manual adjustments, thereby simplifying connection management while ensuring reliable connectivity
Solution Approach 2:
The patent utilizes parameter changes by varying audio output volume parameters based on measured SPL values. The control device adjusts the audio output volume parameter by selecting different values from the pre-configured lookup table, allowing the system to adapt to different acoustic environments and device characteristics without increasing management complexity
2Measurement precision
If audio data output volume is increased to improve sound pressure level, then SPL measurement accuracy improves, but distortion increases
Solution Approach 1:
The patent applies partial action by using multiple volume levels rather than a single high volume for calibration. The control device transmits test streams at different volume levels (e.g., first volume level and second volume level) and selects the appropriate volume value from the lookup table based on the measured SPL, avoiding the need to always use maximum volume and thereby preventing distortion while maintaining measurement accuracy
Solution Approach 2:
The patent implements feedback by measuring the actual SPL output of the connected device and using this measurement to select the appropriate audio output volume value from the pre-configured lookup table. The control device receives SPL information, compares it with target values, and adjusts the volume parameter accordingly, creating a closed-loop system that achieves accurate measurement without excessive volume that would cause distortion
3Manufacturing precision
If test streams are transmitted for calibration, then audio data output consistency across devices is improved, but transmission time and energy consumption increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple volume values in a lookup table before calibration is needed. The table contains audio output volume values corresponding to different SPL scenarios, so when calibration is required, the system can quickly retrieve the appropriate value without extensive real-time testing or calculation, reducing calibration time while maintaining audio data output consistency
Solution Approach 2:
The patent utilizes parameter changes by transmitting test streams at different volume parameters and selecting the optimal value from the pre-configured lookup table. This approach allows the system to achieve consistent audio output across devices by adjusting the volume parameter based on measured SPL, without requiring lengthy calibration procedures
Data Source
AI summary
A method performed by a control device includes transmitting, to a first device, a signal for configuring an audio data output volume of the first device as a reference value, transmitting, to the first device, a test stream for calibration on an audio data output volume of devices consisting of a multi-channel surround system, and measuring an audio data output of the first device based on the reference value and the test stream. Further operations include transmitting, to second and third devices, a signal for configuring an audio data output volume of each of the second and third devices as a specific value, transmitting the test stream to the second and third devices, and measuring audio data outputs of each of the second and third devices which is outputted based on the specific value and the test stream.