Multi-Loudspeaker Calibration Using Hybrid Frequency-Segmented Signals

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Solution Overview

Problem

Existing media playback systems face challenges in accurately calibrating multiple loudspeakers in a concurrent manner without interference, as simultaneous emission of calibration sounds can lead to overlapping frequencies, making it difficult for control devices to obtain high-quality measurements and correlate the sounds with individual speakers.

Innovation Solution

The implementation of a hybrid calibration sound that includes a noise component for low frequencies and a swept signal component for higher frequencies, with staggered emission and extended duration to prevent interference, allowing for effective calibration of multiple playback devices while maintaining spatial resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple loudspeakers emit calibration sounds simultaneously, then calibration time is reduced, but frequency overlap occurs making measurement correlation difficult

Engineering Contradiction:

Improvecalibration speedVSAvoidsound correlation accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The calibration process is segmented by assigning different frequency ranges to different loudspeakers. Each loudspeaker emits calibration sounds within its designated frequency band, preventing frequency overlap while maintaining concurrent operation. This segmentation allows simultaneous calibration of multiple speakers without measurement correlation issues.

Inventive Principle:

Principle #1Segmentation

2Productivity

If calibration sounds are emitted concurrently, then calibration efficiency increases, but interference between sounds degrades measurement quality

Engineering Contradiction:

Improvecalibration efficiencyVSAvoidmeasurement quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The audible frequency spectrum is divided into multiple non-overlapping bands, with each loudspeaker assigned a specific band. This frequency segmentation eliminates interference between concurrent calibration sounds while maintaining measurement quality and calibration efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each loudspeaker operates with distinct local quality characteristics by emitting calibration sounds at unique frequency ranges specific to its position and assignment. This local frequency allocation prevents global interference across the system while enabling concurrent operation.

Inventive Principle:

Principle #3Local quality

3Device complexity

If a single frequency range is used for all loudspeakers, then equipment requirements are simplified, but frequency overlap prevents accurate individual calibration

Engineering Contradiction:

Improveequipment configurationVSAvoidcalibration accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The frequency spectrum is segmented into distinct ranges assigned to different loudspeakers. This segmentation maintains simple equipment configuration while achieving accurate individual calibration through frequency-based differentiation rather than complex hardware modifications.

Inventive Principle:

Principle #1Segmentation

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

This approach enables precise calibration of multiple loudspeakers by avoiding frequency overlap and ensuring sufficient energy is emitted at each frequency, improving the accuracy of acoustic parameter adjustments and enhancing the overall listening experience.

Implementation Method 1

causing the one or more speakers to emit a calibration sound that cycles through frequencies of a calibration frequency range

Methodology Applied

Scientific EffectElectroacoustic transduction:

Implementation Method 2

detecting, via a microphone, the emitted calibration sounds

Methodology Applied

Scientific EffectAcoustic transduction:

Data Source

PatentUS10390159B2Concurrent multi-loudspeaker calibration

Publication Date: 2019.08.20 SONOS INC

AI summary

Examples involve calibration of two synchronous playback groups. In an example implementation, a first playback device forms a first group with a second playback device. While formed into the first group, the first playback device plays back a first calibration sound contemporaneously with the second playback device. The first playback device forms a second group with a third playback device. While formed into the second group, the first playback device repeatedly plays back a second calibration sound contemporaneously with the third playback device. The first playback device receives data representing (i) first audio processing coefficients and (ii) second audio processing coefficients. The first playback devices applies the first audio processing coefficients to playback of audio content when formed into the first group and the second audio processing coefficients to playback of audio content when formed into the second group.