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FOR IMMEDIATE RELEASE: June 05, 2007
Contact: Zarina Bhimani, Listen, Inc., 580 Harrison Avenue,
Suite 2A, Boston, MA 02118
Phone: (617) 556-4104 email: zbhimani@listeninc.com
Listen announces the release of SoundMapTM, its new Time Frequency Analysis software for impulse response analysis, and detection of loose particles and Rub & Buzz in loudspeakers. It is also valuable for identification of transient effects such as drop out in digital devices including VoIP and Bluetooth headsets. The software enables detailed analysis of signals simultaneously in both the time and frequency domain, and offers four different analysis options - Cumulative Spectral Decay (waterfall plots), Short Time Fourier Transforms (STFT), Wavelet, and Wigner-Ville transforms. With this selection of analysis options, SoundMap offers far more flexibility than conventional ‘waterfall plot’ software, and more accurate and psychoacoustically significant analysis capabilities.
Since SoundMap is an off-line analysis program, it can be used with measurement systems from any manufacturer as it can read data from any WAV file, ASCII text file or even a MLSSA TIM file. Naturally it also fully integrates with Listen’s SoundCheckTM software. The software offers a variety of display options including 3D waterfall plot, intensity map with time and frequency slices, instantaneous spectrum, frequency time curve, time envelope and others. The ability to view a “slice” in either the time or frequency domain enables in-depth examination of any result.
The four different transforms that can be applied to the data make it appropriate for a broad variety of applications. Cumulative Spectral Decay is the traditional tool for impulse response analysis of loudspeakers. It calculates the “ringing” of the loudspeaker for each frequency using the impulse response. Listen’s software enables data to be output in a variety of formats including the widely-used three-dimensional ‘waterfall plots’.
For the detection of manufacturing defects such as loose particles and Rub & Buzz in loudspeakers, measurement of settling time and ringing in devices including loudspeakers and telephones, and analysis of dropouts, discontinuities and instabilities in digital devices, the Short Time Fourier Transform can be used. This is a general purpose algorithm which enables observation of the spectral changes of a signal over time. Wavelet analysis differs from CSD and STFT analysis in that it uses constant percentage bandwidth rather than constant frequency bandwidth. This offers better time resolution at high frequencies and better frequency resolution at the lower end of the spectrum. This is advantageous as it is more psychoacoustically significant and it is easy to see the entire 20Hz – 20kHz spectrum in one picture. The applications for wavelet analysis are generally the same as for STFT analysis; the algorithm selected depends on whether constant frequency or constant percentage bandwidth is preferred.
For detailed analysis of very short events, Wigner-Ville is the ultimate algorithm as it offers an output resolution of one spectrum per sample, the maximum achievable precision. It complements the more commonly used CSD, STFT and Wavelet analysis methods, and is ideal for fine analysis of transients or in-depth observation of rapidly evolving signals.
Example Waterfall Plot from Listen Inc.'s SoundMapTM Software. Download high resolution picture (right click and "save target as")
About Listen, Inc.
Listen, Inc. (www.listeninc.com) is a world-leading developer of audio test and measurement software tools and complete measurement systems for R&D and production test of electroacoustic products including loudspeakers, microphones, handsets, headsets, telephones, cell phones, VoIP telephony products, and hearing aids. Formed in 1995, Listen’s electroacoustic test systems have become the standard test platform at many of the world’s largest loudspeaker manufacturers.
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