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Dan LopezDan Lopez

Ben RohnerBen Rohner

Erin LoutzenhiserErin Loutzenhiser

Directionally Adaptive Microphone

For use in classrooms, conference rooms, oranywhere else needing a multidirectionalmicrophone.For use in classrooms, conference rooms, oranywhere else needing a multidirectionalmicrophone.

Uses digital signal processing (DSP) and customalgorithms to “follow” conversations taking placearound it.Uses digital signal processing (DSP) and customalgorithms to “follow” conversations taking placearound it.

Directionally Adaptive Microphone

Pod shaped design – 9” diameterPod shaped design – 9” diameter

Uses 8 directional microphonesUses 8 directional microphones

Active microphone(s) are determined based onSound Pressure Level (SPL) detected at eachmicrophone.Active microphone(s) are determined based onSound Pressure Level (SPL) detected at eachmicrophone.

Microphone threshold settingsMicrophone threshold settings

On/Off and Mute functionsOn/Off and Mute functions

Ceiling mount or tabletopCeiling mount or tabletop

Directionally Adaptive Microphone

Two segments of the system weremodeled:Two segments of the system weremodeled:

Microphone - DSP Algorithms and decisionmaking processMicrophone - DSP Algorithms and decisionmaking process

Environment - Room environment and soundinterface with systemEnvironment - Room environment and soundinterface with system

Microphone Model

Input Power AnalysisInput Power Analysis

Calculate average power of 50 ms block ofdata using the mean of the squaresCalculate average power of 50 ms block ofdata using the mean of the squares

Stored separately from audio data (Originaldata is retained)Stored separately from audio data (Originaldata is retained)

Threshold ComparisonThreshold Comparison

Compare average power calculated to a setthreshold level for each microphoneCompare average power calculated to a setthreshold level for each microphone

If power is less then threshold, that input isconsidered zero for processing purposesIf power is less then threshold, that input isconsidered zero for processing purposes

Microphone Model

Decision Making ProcessDecision Making Process

For each 50 ms block all 8 average powersare compared and the two greatest arepassed on.For each 50 ms block all 8 average powersare compared and the two greatest arepassed on.

Upon initialization microphones 1 and 2 areselected as outputsUpon initialization microphones 1 and 2 areselected as outputs

A microphone must be greater than thecurrent selected microphones for at least 200ms before a switch occursA microphone must be greater than thecurrent selected microphones for at least 200ms before a switch occurs

Prevents rapid switchingPrevents rapid switching

Microphone Model

ReconstructionReconstruction

The selected microphones and sound sourceare used to reconstruct the outputThe selected microphones and sound sourceare used to reconstruct the output

Data is outputted as standard audioData is outputted as standard audio

Microphone Model Demonstration

Sound AttenuationSound Attenuation

The sound attenuationdue to distance wasmodeled as theinverse of the distanceThe sound attenuationdue to distance wasmodeled as theinverse of the distance

ATTN=1/RATTN=1/R

Environment Model

Microphone CoverageMicrophone Coverage

Microphones arrayedat 45 degree intervalsMicrophones arrayedat 45 degree intervals

Each microphone hasa coverage range of48 degrees.Each microphone hasa coverage range of48 degrees.

Adjacent microphonecoverage zonesintersect at 5 feet fromthe DAM-360Adjacent microphonecoverage zonesintersect at 5 feet fromthe DAM-360

Environment Model

Environment Model

Test area is a room20’x20’ with the DAM-360 at the center withdata points at 1”intervalsTest area is a room20’x20’ with the DAM-360 at the center withdata points at 1”intervals

Overall environmentmodel created bycombining the soundattenuation and themicrophone coverageOverall environmentmodel created bycombining the soundattenuation and themicrophone coverage