audio measurements
DESCRIPTION
Audio Measurements. Su, Amit, David, Muthu. Outline. Microphone Introduction to Win CE Audio data collecting with iPAQ Audio data analysis. Introduction to microphones. What is microphone? Microphone is a transducer -- an energy converter. - PowerPoint PPT PresentationTRANSCRIPT
Audio Measurements
Su, Amit, David, Muthu
Outline
Microphone Introduction to Win CE Audio data collecting with iPAQ Audio data analysis
Introduction to microphones What is microphone?
Microphone is a transducer -- an energy converter.
It senses acoustic energy (sound) and translates it into equivalent electrical energy.
How it works? Dynamic Microphones
Good reliability, need little
maintenance fairly good signal-to-
noise ratio Bad
no "tailored" response
How it works?
Condenser Microphones Good: high-quality perform
ance Ability to respond to transi
ent sounds extended high-frequency r
esponse weigh less smaller
Bad sensitive to mechanical no
ise Other Types of Micropho
nes Ribbon microphone Phantom Power
How to choose microphone
Microphone specifications Decibel (dB) scale
Measures how sensitive the microphone is. Frequency Response
“Bandwidth“ of microphone Multiple frequency response
“Bandwidths“ for sound coming from different directions On-axis response
Response to sound coming directly to the microphone Off-axis responses
Response to sound coming from all angles
Microphone specifications
Diffuse field responseResponse to sound coming from reflections
Polar Responsehow certain frequencies are reproduced when they enter the
microphone from a circle Equivalent noise level
noise from microphone itself (good if <15db) Sensitivity
what voltage a microphone will produce at a certain sound pressure level
SPL handling capability (Sound pressure level)Where a certain Total Harmonic Distortion (THD) occurs.Where the signal from the microphone will clip, that is the
waveforms will become squares.
Outline
Microphone Introduction to Win CE Audio data collecting with iPAQ Audio data analysis
Windows CE Architecture
Windows CE Design Principles Small Memory Modular Approach Processor Portability Win32 Compatibility Comprehensive Development Tool Support Connectivity Real Time Processing
Win32 Programming Model Utilises a large subset of the Win32 API (No Win16
support) Supports MFC, VC and VB (eMbedded)
Windows CE Architecture
OEMOEM HardwareHardwareOEMOEM HardwareHardware
Embedded ShellEmbedded ShellEmbedded ShellEmbedded Shell
ApplicationsApplicationsApplicationsApplications
WIN32 APIsWIN32 APIsCOREDLL, WINSOCK, OLE, COMMCTRL, COMMDLG, WININET, TAPICOREDLL, WINSOCK, OLE, COMMCTRL, COMMDLG, WININET, TAPI
WIN32 APIsWIN32 APIsCOREDLL, WINSOCK, OLE, COMMCTRL, COMMDLG, WININET, TAPICOREDLL, WINSOCK, OLE, COMMCTRL, COMMDLG, WININET, TAPI
Windows CE Shell ServicesWindows CE Shell ServicesWindows CE Shell ServicesWindows CE Shell Services
Remote Remote ConnectivityConnectivityRemote Remote ConnectivityConnectivity
KernelKernelLibraryLibraryKernelKernelLibraryLibrary
IrDAIrDAIrDAIrDA
GWESGWESGWESGWES Device Device ManagerManagerDevice Device
ManagerManagerFileFile
ManagerManagerFileFile
ManagerManagerTCP/IPTCP/IPTCP/IPTCP/IP
OALOALBootloaderBootloader
OALOALBootloaderBootloader DriversDriversDriversDrivers DeviceDevice
driversdriversDeviceDevice driversdrivers File driversFile driversFile driversFile drivers
MicrosoftMicrosoftMicrosoftMicrosoft OEMOEMOEMOEM ISV, OEMISV, OEMISV, OEMISV, OEM
Developer Issues
Windows CE Memory Model Protected Address Space Virtual Memory
Memory Allocation Stack Heap Virtual Memory (VirtualAlloc) Memory mapped files
Processes and Threads No process priority classes Threads with the same priority
run in a round-robin fashion Number of threads only limite
d by available memory
Reserved for system
64KB Guard
Memory Mapped Files
Process Slot 1(32MB)
Process Slot 0 (32MB)
Process slot 32 (32MB)
4GB
3GB
2GB
1GB
0GB
.
.
.Process Slot 2 (32MB)
.
.
.
Developer Issues
File System No Concept of Current Directory No Support for Overlapped I/O Support for Installable and Remote File Systems
Power Issues Porting Win32 Applications
Unicode GDI differences User interface issues – e.g. no mouse
Tool Support eMbedded Visual C++ eMbedded VB Visual Studio .NET
Outline
Microphone Introduction to Win CE Audio data collecting with iPAQ Audio data analysis
My own experience
Life cycle on data analysis Background Difficulties Achievement Demo
Clean Data
Analysis Data
Collect Data
Build Application
Audio data
What is audio data To human: something
you can hear To computer: digital
signals What is audio data
features Energy zero-crossing Spectrum ……
Where audio data being used?
Engineering Acoustics Acoustic signal processing musical sounds synthesis and composition
Physical Acoustics Ultrasonics and infrasonics Propagation of sound through the atmosphere, fluids, and fluid-f
illed materials Psychological and Physiological Acoustics
Speech Recognition and Generation Physiology and biophysics of the ear, the auditory nerve, and hi
gher neural centers Others
Acoustical Oceanography Architectural Acoustics
Data collecting procedure
Tools used in our data collecting iPAQ build in mirophone Microsoft embedded C++
How? On iPAQ
Record, compress, send
On serverReceive, unzip, concat
Difficulties
Which recorder is better? Windows build in recorder control vs. self-developed
wav recorder Why choosing self-developed wav recorder?
Guessing …
Measure accuracy Channels – one or two data stream
Mono Stereo
Bit per sample – how good each sample is 8 bit 16 bit
Sample rate – how many samples are taken each second? 8.0 kHz (telephone quality) 11.025 kHz 22.05 kHz (FM radio quality) 44.1 kHz (CD quality)
File size Channel * Bit/sample * Sample rate * sample time
Procedure
Record Prepare
Open a connection with the device using this handleAllocate a buffer for incoming data
Reading data Write to wave file
Compress/Uncompress Standard zip/unzip
Send/Receive Sockets similar to ftp
Achievements
Let us do the demo now…
Future Improvements
Better headset Better Compression
More efficient algorithm? Online zipping
Make data streaming Weakness
Each file length is limited by iPAQ memory
Total recording depends on wireless link
Your own file format What if wireless link is brok
en?
Outline
Microphone Introduction to Win CE Audio data collecting with iPAQ Audio data analysis
Data Cleaning and Analysis
What is noise? From textbook
Sound - the occurrence of an audible event Noise – nonperiodic sound
To us Sound – signal data we are interested in Noise – signal data that is useless to us
How to remove noise? Example 1- data are mixed. pick up certain people’s voice while he is talking with a group. Example 2 – data are sparse. Is there any cell phone rings during a 3 hours meeting?
Data Processing
Given voice samples, what can we get from it? Volumn Picth Spectrum …
What can we do with it?
Audio data from Telcordia
What is pattern inside?
Future Work
On-line processing Server side Client side - Fat
sensor?
Fusing network
Future Work
Data Annotation?
Applications
Location detector Scenario 1: Prof. Muthu is sleeping on the trai
n, but he does not worry about missing New Brunswick…
Smart filterScenario 2: Prof. Muthu preparing his lecture
notes on the train. And David will call him around that time. He does not want to be interrupted except that call…
A little test for fun
Given voice samples from David, Amit and Su. Can you tell them apart?
A little hint
Result
1- Amit 2 – David 3 - Su