Last Updated: 20060821, mei
P12 - Posters: Measurements & Modeling
Friday, October 6, 4:00 pm — 5:30 pm
P12-1 The Accuracy and Consistency of Spectrographic Analysis for Voice Identification—Jeff Smith, University of Colorado at Denver - Denver, CO, USA
This test investigated the accuracy and consistency of voice identification comparisons made by five trained examiners over a three week period. These individuals were all students of the University of Colorado at Denver and had taken a semester-long course in Audio Forensics with limited training in voice identification. Each week, examiners conducted eight closed-trial comparisons of four clue-phrases from both male and female speakers. In simulating a closed set spectrographic line-up, each comparison consisted of spectrograms from a pool of four “known” speakers and one “unknown” speaker—audio recordings of the known and unknown speakers were made nine months apart. From the pool of known speakers, the examiner made a positive identification match to the unknown. After the three week period, data reveled that examiners reached the same conclusion in all three examinations for only 50 percent of the comparisons. The average accuracy of these examinations was 65 percent. This paper discusses the outcome of the experiment including interpretation of these and other results.
Convention Paper 6920 (Purchase now)
P12-2 Loudspeaker Thermal and Safety Data Acquisition System—Marshall Buck, Psychotechnology, Inc. - Los Angeles, CA, USA
A four-channel data acquisition system has been designed for measurement of four parameters needed for safety and thermal testing and modeling in a voice coil driven loudspeaker: voice coil temperature, RMS voltage drive, current, and true V x I power dissipated. These data are stored in Excel format for postprocessing. Safety tests with alternating or direct current stimulation require the current versus time displays needed for pretesting to UL 1480 and ANSI/CEA-636 standards. Rated at 32 amperes and 125 volts, the instrument is suitable for voice coils rated up to 5000 Watts. A real-time graphics display on a standard PC is implemented with a USB interface.
Convention Paper 6921 (Purchase now)
P12-3 Surface Scattering Uniformity Measurements in Reflection-Free Environments—Lorenzo Rizzi, LAE - Laboratorio di Acustica ed Elettroacustica - Parma, Italy; Angelo Farina, Università di Parma - Parma, Italy; Paolo Galaverna, Genesis Acoustic Workshop - Parma, Italy; Paolo Martignon, Lorenzo Conti, Andrea Rosati, LAE - Laboratorio di Acustica ed Elettroacustica - Parma, Italy
Following previous investigations, carried out at the University of Parma in 1999 and 2000, LAE (Laboratory of Acoustics and Electroacoustics) started a new measurement campaign to compare with the original results on the same type of diffusor panels, to verify AES-4id-2001 measurement standard, and to investigate the nature of scattering phenomena in more detail. Measurements were conducted on the floor of a large closed space to obtain a reflection free time window, long enough to study the first reflection from the panel; the use of sine sweep excitation signals instead of the recommended MLS ones permits to ameliorate the acquisition process. The present paper discusses research background studies and the results from the first round of measurements.
Convention Paper 6922 (Purchase now)