Audio System Measurement and Improvement Group 10 AdvisorJaijeet Roychowdhury TeamMohamud Ismail Franklin Wong Andrew Johnson Garett Kauer.

Audio System Measurement and Improvement

Group 10Advisor Jaijeet Roychowdhury

Team Mohamud Ismail

Franklin Wong

Andrew Johnson

Garett Kauer

Outline

Purpose Solution Requirements / Specs Budget / Timeline Conclusion

Purpose

http://www.techexcess.net/images/products/Dell/dell-a225.jpg

http://www.theage.com.au/ffximage/bose_wideweb__470x367,2.jpg

Turn Cheap Dell A225 PC Speakers

Into speakers comparable to much more expensive speakers with an easy to use device that has a low consumer cost

Quick Explanation in Frequency Analysis

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Our Solution

Speaker MicrophoneComputer

Feedback

Known Spectrum

Unknown spectrum

Known after processing

Our Solution

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Frequency Response of Entire System

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Entire System after precoding

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Frequency Response of white noise

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Frequency Response of Speakers

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Frequency Response of Room

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Frequency Response of Microphone

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http://www.copystars.com/images_products/shure_pgx24pg58_s19016.jpg

Software Design

What Software DoesMeasurement System

Measures, Displays and Compares Transfer Functions

De-embedding/Correction System Generates Inverse Transfer Function Precodes Output

Done Using ALSA

Software Design

Specifications To MeetMeasurement System

Greater than 20dB of relative nulling over 1-5kHz

De-embedding/Correction System Corrected transfer function Flat to within 5dB over 100Hz-10kHz

Software Design

ALSAAdvanced Linux Sound ArchitectureProvides audio and MIDI functionality to LinuxHandles Sound Device DriversUser Space Library

Simple Application Programming Provides High Level Functionality

Software Design

ALSA Efficient support for all types of sound devices Fully modularized sound drivers Thread-safe design Supports Open Sound System (OSS)

Software development will be open source, created to operate using a Linux system. Project software will comprise two separate systems. The first will be used to measure the audio response within a room by interfacing with a microphone. The second system will be used to correct the speaker output to adjust for linear non-idealities produced by the audio system and room acoustics.

Microphone Selection

Graphic provided by Shure Incorporated www.shure.com

“Performance Gear Microphone Guide”

Selection Considerations

Frequency Response Range of Reception Ease of Use Durability Cost

Frequency Response

Relative Frequency Response

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Ideal Response Shure PG58 Response

Response provided by Shure Incorporated www.shure.com

“Performance Gear Microphone Guide”

Range of Response

Reception at <15cm Direct proximity to Microphone head Simulates Ear perception

Budget

Quantity Item Price

1 PC with Speakers (provided) $0.00

1 Shure PG58 microphone $69.95

Total $69.95

TimelineTask Name Start Finish

Audio Enhancement Device 1/28/2008 5/13/2008get linux box up and running 1/28/2008 2/15/2008find and purchase microphone 2/4/2008 2/29/2008link microphone and PC 3/3/2008 3/7/2008implement Xfer Fn finder/invertor 3/10/2008 3/14/2008link transfer function to ALSA 3/17/2008 3/21/2008test 3/24/2008 4/4/2008create user friendly UI 4/7/2008 4/11/2008prepare final prototype 4/14/2008 4/25/2008buffer 4/28/2008 5/13/2008

E B M E B M E B M E B M EJanuary February March April May

Complete

In Progress

In Conclusion…

Want to improve cheap speakers

Correct the distortion inherent in room and speakers

End-user needs only software and a microphone

Software should be free and easy to use

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http://www.popculturecomics.com/graphics

Project Future

Created software distributed as open- source, but…

Load software onto small self-contained device

No PC needed Commercial potential

Calibrate Button

MicrophoneLine Out

Audio Input

Questions?

Audio System Measurement and Improvement Group 10 AdvisorJaijeet Roychowdhury TeamMohamud Ismail Franklin Wong Andrew Johnson Garett Kauer.

Documents

alsa slide

khz slide

processing slide

linux system

audio system measurement

audio response

high level functionality

low consumer cost slide