Adaptive Comfort Noise Parameters Through Inactive-Segment Averaging

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Solution Overview

Problem

Existing DTX systems face issues with undesired fluctuations in comfort noise (CN) generation during speech pauses, particularly when the first CN parameter set is based on a single frame or a short period, leading to an annoying listening experience due to rapid changes in background noise characteristics.

Innovation Solution

A method for determining CN parameters by calculating a weighted sum of signal characteristics from the current and previous inactive segments, using weighting functions based on the length of the active segment to stabilize the CN generation, especially in cases where background noise conditions change over time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If CN parameters are sent less frequently to save bandwidth, then transmission bandwidth is reduced, but CN stability deteriorates leading to undesired fluctuations

Engineering Contradiction:

Improvetransmission bandwidthVSAvoidcomfort noise stability

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The system performs preliminary averaging of CN parameters over multiple frames before transmission. Instead of transmitting raw single-frame parameters that cause fluctuations, the encoder averages parameters across several frames (e.g., 8 frames) in advance, so that the transmitted parameters represent a stable baseline that reduces fluctuations when used by the decoder during speech pauses.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If CN parameters are based on a single frame or short period, then encoding complexity is reduced, but CN quality deteriorates due to rapid changes in background noise

Engineering Contradiction:

Improveencoding complexityVSAvoidcomfort noise quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system merges multiple frames of CN parameters into a single averaged parameter set for transmission. By combining information from multiple frames (e.g., averaging spectral shape and energy parameters across 8 frames), the system creates a more reliable and stable CN representation that better represents the background noise characteristics, while still maintaining efficient single-frame transmission.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If CN parameters are updated frequently to track background noise changes, then adaptability improves, but transmission bandwidth increases

Engineering Contradiction:

Improvebackground noise trackingVSAvoidtransmission bandwidth

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The system implements periodic transmission of CN parameters at specific intervals (e.g., every 8 speech encoder frames) rather than continuous transmission. This periodic update strategy allows the system to track background noise changes over time while maintaining bandwidth efficiency. The averaged parameters transmitted at these periodic intervals provide stable CN during speech pauses without requiring frequent updates.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20250299683A1Adaptive comfort noise parameter determination

Publication Date: 2025.09.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method for generating a comfort noise (CN) parameter is provided. The method includes receiving an audio input; detecting, with a Voice Activity Detector (VAD), a current inactive segment in the audio input; as a result of detecting, with the VAD, the current inactive segment in the audio input, calculating a CN parameter CNused; and providing the CN parameter CNused to a decoder. The CN parameter CNused is calculated based at least in part on the current inactive segment and a previous inactive segment.