Past Research Projects In the IAL

Human Capabilities of Speech Dereverberation

Sponsor: Georgia Tech

Investigators: Brad Libbey and Dr. Peter Rogers

Overlap-masking is auditory masking of a phoneme by a previous phoneme in a reverberant environment. The result can affect the intelligibility of speech. To explore this possibility, phonetically balanced word lists are recorded in the IAL anechoic chamber. A real room reverberates these anechoic recordings which are subsequently presented to human listeners. Word intelligibility is then compared across several factors, including, anechoic vs. reverberant, diotic vs. binaural, and processed vs. unprocessed. Preliminary results indicate that overlap-masking does not entirely explain the loss of intelligibility associate with reverberant words. Nor does binaural masking release explain the binaural advantage when listening to reverberant words. These results indicate that peripheral overlap-masking affects reverberant intelligibility in a minor way.

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Developement of the Integrated Acoustics Laboratory

Phase I: Acquisition of an anechoic chamber and associated instrumentation

Sponsor: Ford Motor Company, National Science Foundation, Georgia Tech
Participants: Yves Berthelot and Krishan Ahuju

Status: Completed
This project will construct and instrument a state of the art anechoic facility on the Georgia Tech campus beginning in 1997. The thrust of the facility is to provide the capability for closely integrated design, modeling and testing for vibration and acoustical considerations. The facility will include a scanning laser vibrometer, systems for acoustic holography and intensity mapping, a VXI data acquisition system incorporating 32 channels of 0-52 kHz sampling, one channel at 20 MHz sampling, 16 channels of D/A, and a four-channel arbitrary source. In addition, the lab will add two workstations. One of the workstations will serve as the VXI front end, while the other will be used for modeling and simulations, using such codes as MSC/NASTRAN, SYSNOISE, AAC COMET/Acoustics, and others.

 

 

Evaluation of criticality alarm system testing

Sponsor: ERDA/Westinghouse Savannah River
Participants: Kenneth A. Cunefare, and Brian Van Biesel, Research Engineer II

Status: Completed
The objective of this research is to investigate the methods and alternatives used to determine the audibility of criticality alarm systems. Included within the scope is the impact the presence of personal protective clothing (hoods, air suits, respirators) has on the ability of the wearer to hear an alarm. The project also includes sound power measurements on a number of portable devices.

 

 

Laser vibrometer study of a stiffened aluminum panel

Sponsor: Georgia Tech
Investigators: Janeen Jones, Kenneth A. Cunefare

Status: Completed
This project was used as a vehicle to commission the Polytec Scanning Laser Vibrometer system. We applied it the modal analysis of a rib-stiffened aluminum panel. The panel was provided to us by a maker of general aviation business jets, and is representative of typical fabrication practices. We compared the Polytec against classical experimental modal analysis methods using accelerometers. The results substantiated the efficiency gains (reduced time) of the laser system over accelerometer methods.

 

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Vibro-acoustic characterization of an automotive A.I.R. pump

Sponsor: Georgia Tech
Investigators: David Moon Kenneth A. Cunefare

Status: Completed
This project was used as a vehicle to commission the VXI/LMS data acquisition system We applied it to the study of the acoustic radiation and vibration characteristics of an automotive component, an A.I.R. pump used as part of an emissions control system.

 

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Laser Vibrometer Microphone Measurements

Sponsor: Georgia Tech
Investigators: Lance Willis, Georgia Tech Acoustics Group, and Guy Torio, Electroacoustic Development, Shure Brothers

Status: Completed
This project investigated the utility of laser vibrometer measurements for new microphone development projects. The project considered microphone diaphragm displacement and velocity profiles for two different mic types. The mics were a dual element condenser cartridge and a typical dynamic cartridge with the resonator element removed. The mics were excited by a loudspeaker, while the laser vibrometer scanned the surface of the diaphragms to produce the desired profiles.

 

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Investigations of fastener installation noise (Completed)

Sponsor: Huck International
Participants: Van Biesel

Student: Mark Fowler
The objective of this project is to experimentally determine the noise generation mechanisms associated with the installation process for a particular high-performance fastener.

 

Investigations of acoustic emission from trabecular bone (Completed)

Sponsor: Petit Institute for Bioengineering and Bioscience, Integrated Acoustics Laboratory
Participants: Prof. Robert Gudlberg, Prof. Chris Lynch

Student: Lisa Chang
The objective of this project is to experimentally assess the acoustic emission from normal and osteoporotic trabecular bone.