Bass Extraction and Routing for 3D Audio Bass Build-Up

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Solution Overview

Problem

Current audio processing methods for complex home theater systems face challenges in accurately reproducing low-frequency sounds due to bass build-up issues, especially in 3D speaker layouts, where traditional bass management techniques can lead to undesirably high amplitudes and complexity in rendering sounds across multiple channels.

Innovation Solution

The method involves applying a bass extraction process using low-pass filters to audio object signals and Higher Order Ambisonics (HOA) data, followed by a bass management process that routes extracted low-frequency signals to appropriate speakers, limiting amplitudes and combining them with high-pass filtered signals to mitigate bass build-up and improve sound reproduction in multi-channel environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional bass management techniques are applied in complex home theater systems with multiple speakers, then the system can reproduce low-frequency sounds, but bass build-up occurs leading to undesirably high amplitudes

Engineering Contradiction:
Improvelow-frequency sound reproduction accuracyVSAvoidbass build-up
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The audio signal is segmented into different frequency components using filter banks. Low-frequency signals are extracted and processed separately from mid and high-frequency signals, allowing independent bass management without affecting other frequency ranges. This segmentation prevents bass build-up by controlling low-frequency content separately.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Bass signals are extracted from the multi-channel audio signal using low-pass filters and filter banks. The extracted bass signals are then managed separately through a dedicated bass management process that routes them to appropriate speakers while controlling amplitude, preventing the harmful bass build-up effect.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If bass extraction process is applied to audio object signals and HOA data, then low-frequency signals can be isolated and managed, but the processing complexity increases

Engineering Contradiction:
Improvebass management accuracyVSAvoidprocessing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Bass extraction is performed as a preliminary step before rendering audio objects to speaker feeds. By extracting and managing bass signals in advance, the system establishes controlled low-frequency content before the complex rendering process, simplifying subsequent processing while ensuring accurate bass management.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A dedicated bass management process acts as an intermediary between the audio object rendering pipeline and the final speaker output. This intermediary component handles low-frequency signals separately, managing the complexity of bass extraction and routing without burdening the main rendering pipeline.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If array processing methods are used with legacy channel-based audio data, then the system can adapt to different speaker configurations, but bass build-up may result from power equivalent level duplication

Engineering Contradiction:
Improvespeaker configuration adaptabilityVSAvoidbass build-up
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The audio signal is segmented by frequency before array processing. Low-frequency components are extracted and processed separately from the main audio signal, allowing the array processing to operate on high-frequency content only. This prevents bass build-up while maintaining adaptability to different speaker configurations through the separate bass management path.

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 effectively reduces bass build-up and enhances the accuracy of low-frequency sound reproduction in complex playback environments by isolating and managing low-frequency signals before rendering, ensuring balanced audio output across multiple speakers.

Implementation Method 1

applying a bass extraction process involving low-pass filters to the audio object signals and to a first portion of Higher Order Ambisonics (HOA) audio data, to produce extracted low-frequency audio signals

Methodology Applied
Scientific EffectLow-pass filtering: Filter (electronic)

Implementation Method 2

applying a high-pass filter to at least some of the audio object signals, to produce a first high-pass filtered audio signals

Methodology Applied
Scientific EffectHigh-pass filtering: Filter (electronic)

Implementation Method 3

A bass management process involves routing the extracted low-frequency audio signals to the one or more speakers capable of reproducing low-frequency audio signals

Methodology Applied
Scientific EffectSignal routing:

Data Source

PatentEP3474575B1Bass management for audio rendering
Publication Date: 2020.05.27 DOLBY LABORATORIES LICENSING CORP
  • EP3474575B1 patent drawingFigure 1
  • EP3474575B1 patent drawingFigure 2
  • EP3474575B1 patent drawingFigure 3A~3B

AI summary

Improved methods and devices for processing low-frequency audio data are provided. A bass extraction process may involve applying low-pass filters to received audio object signals, to produce extracted low-frequency audio signals. The bass extraction process may be performed prior to a process of rendering audio objects into speaker feed signals. A bass management process may involve routing the extracted low-frequency audio signals to the one or more speakers capable of reproducing low-frequency audio signals.