Sunday, May 21, 14:00 — 14:45
EB03-01 Optimization of the Overall Scattering Factor for the Acoustic Simulation of Classrooms
Dragan Novkovic (Presenting Author), Stefan Dimitrijevic (Author)
An educational facility used for lectures and multimedia presentations was acoustically measured and simulated in the acoustic simulation software EASE. After processing the acquired data, large discrepancies between the results obtained by impulse response measurement and those obtained from the simulation were observed. All materials, whose data were entered into the simulation, were described solely by absorption coefficients without any information about the scattering, which is common in such situations. Overall simulated scattering factor was adjusted in such way to allow matching of measured and simulated results within a reasonable tolerance limits. As a result of this process, the authors have discussed the possible approaches for the optimization of this parameter in the process of software simulation of acoustically similar spaces.
Engineering Brief 319
EB03-02 High Frequency—Ultra Audio Band Mode Voice Coil Temperature Measurement
Isao G. Anazawa (Presenting Author)
As the power driving mobile devices loudspeaker increases for a better audio experience, an accurate measurement of the voice coil temperature becomes necessary in order to protect the loudspeaker from over-heating. Electrical solutions have been developed in the past to measure the temperature indirectly from the voice coil resistance using a low frequency probe tone or using main audio contents. This paper explains an ultra-audio band high frequency probe to measure the resistance. The test results show good accuracy without the known side effects that exist with current methods.
Engineering Brief 320
EB03-03 U 87—Microphone Development in the 1960s
Martin Schneider (Presenting Author)
The U 87 was introduced in 1967 as part of the first generation of transistorized condenser microphones. In the 1960s many aspects like dynamic range, powering, and the seemingly simple question of connectors had to be reconsidered differently from the preceding generations of tube microphones, and for the new recording environments of the time. A detailed look at this microphone and its many variants (for different countries, and different powering schemes) give an insight into the spectrum of development topics and recording technology of the 1960s and 1970s.
Engineering Brief 321