Loudspeaker Localization Using Signature Tones in Noisy Rooms
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Solution Overview
Problem
Existing loudspeaker systems struggle to accurately estimate both distance and angle between multiple speakers for immersive sound generation, leading to potential failures in auto-calibration and suboptimal audio quality due to noise, obstructions, and outliers.
Innovation Solution
A system and method utilizing time-frequency masking (TFM) for asynchronous distance estimation and impulse response (IR) based direction of arrival (DOA) estimation to robustly determine speaker distances and angles, incorporating a controller with microphones to process audio signals and perform calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional distance estimation methods are used between loudspeakers, then the system can operate, but the accuracy is degraded due to noise, obstructions, and outliers
Solution Approach 1:
The system performs preliminary actions by having each loudspeaker transmit its signature tone before distance calculation. The receiving loudspeaker captures the signature tone, extracts timing information, and calculates distance. This preliminary transmission and capture sequence establishes a reliable baseline measurement before environmental factors can degrade accuracy.
Solution Approach 2:
Signature tones serve as acoustic intermediaries between loudspeakers. Each loudspeaker transmits a unique signature tone that acts as a mediator carrying identification and timing information through the acoustic environment. The receiving loudspeaker uses this intermediary signal to determine distance and angle without direct electronic communication between devices.
2Measurement precision
If signature tones are transmitted for distance estimation, then distance and angle can be determined, but noise and obstructions interfere with accurate measurement
Solution Approach 1:
The system extracts timing information specifically from the signature tone portion of the received audio signal. By isolating and extracting only the relevant signature tone data rather than processing the entire audio spectrum, the system removes interfering noise and obstruction effects from the measurement process.
Solution Approach 2:
Each loudspeaker transmits a unique signature tone with distinct acoustic characteristics (frequency, duration, pattern). These differentiated 'acoustic colors' allow the receiving loudspeaker to identify and measure the specific transmitted signal while filtering out background noise and unrelated acoustic interference.
3Loss of information
If asynchronous signature tone transmission is used, then device localization can be achieved, but the system complexity increases due to timing synchronization requirements
Solution Approach 1:
Each loudspeaker independently transmits its signature tone and independently processes received tones from other loudspeakers. The system performs self-service localization where each device captures timing information, calculates its own distance and angle to others, and determines its position without requiring centralized coordination or complex inter-device synchronization protocols.
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
Enhances speaker localization robustness, improves graphical user interfaces, and adjusts volume based on distance, ensuring high-quality immersive sound by accurately calibrating speaker positions and overcoming noise and obstruction challenges.
Implementation Method 1
The first loudspeaker transmits a first audio signal including and a first signature tone into a listening environment. The second loudspeaker transmits a second audio signal including a second signature tone into the listening environment and receive the first audio signal including and the first signature tone.
Implementation Method 2
The second loudspeaker performs a time frequency masking operation to extract a least one of the first signature tone from the first audio signal and the second signature tone from the second audio signal prior to determining the estimated distance between the first loudspeaker and the second loudspeaker.
Implementation Method 3
The at least one controller is further programmed to perform an impulse response (IR) measurement operation on the signature tone to determine a difference in peaks for the audio signal received at a first microphone and for the audio signal received at a second microphone to provide a time delay between the receipt of the audio signal at the first microphone and at the second microphone
Data Source
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Figure 3
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AI summary
In at least one embodiment, an audio system including a first loudspeaker and a second loudspeaker and at least one controller is provided. The first loudspeaker transmits a first audio signal including a first signature tone into a listening environment. The second loudspeaker transmits a second audio signal including a second signature tone into the listening environment and receive the first audio signal including and the first signature tone. The second loudspeaker receives the second audio signal including the second signature tone after transmitting the second signature tone into the listening environment and determines an estimated distance between the first loudspeaker and the second loudspeaker based at least on the first signature tone and the second signature tone. The second loudspeaker performs a time frequency masking operation to extract a least one of the first signature tone and the second signature tone from the noisy and reverberant mixture.