Communication Device Audio Rendering Control for Feedback Prevention

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Solution Overview

Problem

In communication systems, particularly for public safety users, there is a challenge with feedback loops and delayed audio playback when using broadband devices as backups to narrowband devices, leading to poor audio quality and user distraction, often due to the audio being played back on one device being picked up by the open microphone of the transmitter, and users forgetting to adjust volume settings.

Innovation Solution

A method to selectively and automatically prevent the rendering of communications on a receiving device when the user is transmitting on an associated device nearby, by determining associations based on identity, physical distance, or common area, to prevent interference and delay issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If audio is played back on a broadband device while the user is transmitting on a narrowband device, then the user can monitor conversations continuously, but feedback loops occur and audio quality becomes unusable

Engineering Contradiction:

Improvecontinuous conversation monitoringVSAvoidfeedback loop interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system proactively prevents feedback loops by detecting when a user is transmitting on one device and automatically muting the loudspeaker on another device before the feedback can occur. This preliminary anti-action blocks the harmful feedback path while preserving the useful dual-device monitoring capability.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system uses feedback from the transmission state of one device to control the audio output state of another device. When the system detects that a user is transmitting on a narrowband device, it uses this feedback information to automatically mute the broadband device's loudspeaker, preventing feedback loops.

Inventive Principle:

Principle #23Feedback

2Reliability

If audio is played back on a broadband device, then the user can receive communications, but delayed playback causes user distraction and reduces communication effectiveness

Engineering Contradiction:

Improvecommunication receptionVSAvoidaudio playback delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system dynamically adjusts the audio playback state based on real-time transmission conditions. Instead of static audio playback, the system mutes the broadband device when delay would be noticeable (during user transmission) and unmutes it when delay is not an issue, adapting to changing conditions to eliminate distracting delays.

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If users manually adjust volume settings to avoid hearing themselves, then feedback loops are reduced, but users forget to adjust volume back up resulting in missed communications

Engineering Contradiction:

Improvefeedback loop reductionVSAvoidmanual volume adjustment

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The system performs automatic volume management without user intervention. It autonomously detects transmission states, determines when feedback loops are likely to occur, and automatically adjusts the loudspeaker volume accordingly. This self-service approach eliminates both the feedback problem and the user error of forgetting to adjust volume.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses feedback from transmission state detection to automatically control volume settings. When the system detects that a user is transmitting on one device, it uses this feedback to automatically reduce or mute the loudspeaker on other devices, eliminating the need for manual user adjustment.

Inventive Principle:

Principle #23Feedback

4Reliability

If multiple communication devices are used for redundancy, then communication continuity is improved, but feedback loops and audio interference occur between devices

Engineering Contradiction:

Improvecommunication continuityVSAvoidinter-device audio interference

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The system proactively prevents inter-device feedback loops by detecting transmission states on multiple devices and preemptively muting loudspeakers on devices that would create feedback paths. This preliminary anti-action preserves the redundancy benefit while blocking harmful interference before it occurs.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system uses feedback from multiple device transmission states to coordinate audio output across devices. When any device detects transmission, this feedback information is used to control loudspeaker states on other affiliated devices, preventing feedback loops while maintaining communication continuity.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8041305B2Selectively rendering a communication at a communication device

Publication Date: 2011.10.18 MOTOROLA SOLUTIONS INC

AI summary

A method to selectively rendering a communication at a receiving communication device comprises receiving a communication and determining whether an association exists between the receiving communication device and a source of the communication. If an association does not exist between the receiving communication device and the source of the communication, rendering the communication at the receiving communication device or distributing the communication to the receiving communication device in order for the communication to be rendered at the receiving communication device. If an association does exist between the receiving communication device and the source of the communication, preventing the communication from being rendered at the receiving device.