Echo Latency Estimation via Percentile-Based Signal Subsampling

Solution Overview

Problem

Existing methods for determining echo latency in audio systems are processor-intensive due to the need for full cross-correlation between reference and input signals, requiring a large number of computations, which is inefficient and costly.

Innovation Solution

The system subsamples the reference signal based on a percentile estimate, selecting only samples with high amplitude values, reducing processing requirements by up to 100 times without compromising precision or time resolution, by using a device that generates a subsampled reference signal and performs cross-correlation with microphone audio data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If full cross-correlation is performed between reference signal and microphone audio data, then accurate echo latency estimation is achieved, but processing consumption increases significantly

Engineering Contradiction:

Improveecho latency estimation accuracyVSAvoidprocessing consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the high-amplitude samples from the reference signal based on percentile estimation, discarding low-amplitude samples that contribute minimally to cross-correlation accuracy. This extraction principle reduces the number of computations required while preserving the essential information needed for accurate echo latency estimation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of performing cross-correlation on the complete reference signal, the patent applies partial action by processing only a subset of high-amplitude samples. This partial processing approach achieves sufficient measurement precision without the excessive computational cost of full-signal processing.

Inventive Principle:

Principle #16Partial or excessive action

2Measurement precision

If full cross-correlation is performed between reference signal and microphone audio data, then accurate echo latency estimation is achieved, but computational complexity increases

Engineering Contradiction:

Improveecho latency estimation accuracyVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the high-amplitude samples from the reference signal based on percentile estimation, discarding low-amplitude samples that contribute minimally to cross-correlation accuracy. This extraction principle reduces the number of computations required while preserving the essential information needed for accurate echo latency estimation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of performing cross-correlation on the complete reference signal, the patent applies partial action by processing only a subset of high-amplitude samples. This partial processing approach achieves sufficient measurement precision without the excessive computational cost of full-signal processing.

Inventive Principle:

Principle #16Partial or excessive action

3Productivity

If reference signal is subsampled based on percentile estimate, then processing requirements are reduced, but signal representation may be compromised

Engineering Contradiction:

Improveprocessing efficiencyVSAvoidsignal representation accuracy

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent applies local quality by selectively retaining high-amplitude samples that contain the most informative content for echo latency detection. Instead of uniform subsampling, the method concentrates processing resources on the most significant signal portions, ensuring that local regions of high importance are preserved while reducing overall data volume.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of signal representation by transitioning from complete signal processing to percentile-based subsampling. This parameter change allows the system to process a reduced set of samples while maintaining the critical characteristics needed for accurate echo latency estimation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10650840B1Echo latency estimation

Publication Date: 2020.05.12 AMAZON TECH INC

AI summary

A device that determines an echo latency estimate by subsampling reference audio data. The device may determine the echo latency corresponding to an amount of time between sending reference audio data to loudspeaker(s) and microphone audio data corresponding to the reference audio data being received. The device may generate subsampled reference audio data by selecting only portions of the reference audio data that have a magnitude above a desired percentile. For example, the device may compare a magnitude of an individual reference audio sample to a percentile estimate value and sample only the reference audio samples that exceed the percentile estimate value. The device generate cross-correlation data between the subsampled reference audio data and the microphone audio data and may estimate the echo latency based on an earliest significant peak represented in the cross-correlation data.