We propose a novel method to determine the complex amplitude of each eigenfunction composing a vibrational wavepacket of / molecular ions evolving with a ~10 fs time scale. We find that the two-dimensional spectrogram of the kinetic energy release (KER) of H(+)/D(+) fragments plotted against the time delay of the probe pulse is equivalent to the spectrogram used in the frequency-resolved optica...

This brief note reports on a study that applies the reassigned spectrogram (the reassigned energy density spectrum of the short-time Fourier transform [STFT]) to develop the dispersion curves for multimode Lamb waves propagating in an aluminum plate. The proposed procedure first uses the spectrogram to operate on a single, laser-generated and detected waveform to develop the dispersion relation...

We introduce a τ -dependent Wigner representation, Wigτ , τ ∈ [0, 1], which permits us to define a general theory connecting time-frequency representations on one side and pseudo-differential operators on the other. The scheme includes various types of time-frequency representations, among the others the classical Wigner and Rihaczek representations and the most common classes of pseudo-differe...

The authors are with the Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287. (Emails: [email protected], [email protected], [email protected]) This work was supported by the National Science Foundation grant CCLI DUE – 0089075. Abstract  Time -frequency representations (TFRs) such as the spectrogram are important two-dimensional tools for processing time-varying sign...

We present a method for phoneme recognition using an expert system combining spectrogram reading knowledge and neural networks, and we report its performance. The proposed expert system consists of two parts : (1) phoneme segmentation based on spectrogram reading knowledge used by human experts, and (2) phoneme identification using neural networks applied to the phoneme boundaries determined in...

The modification of magnitude spectrograms is at the core of many audio signal processing methods, from source separation to sound modification or noise canceling, and reconstructing a natural sounding signal in such situations is thus a very important issue. This article presents recent theoretical and experimental developments on the application to signal reconstruction from a modified magnit...

In this paper, we propose a robust environmental sound spectrogram classification approach. Its purpose is surveillance and security applications based on the reassignment method and log-Gabor filters. Besides, the reassignment method is applied to the spectrogram to improve the readability of the timefrequency representation, and to assure a better localization of the signal components. Our ap...

This paper proposes a novel spectrogram factorization method, called log-normal matrix factorization (LogNMF). Conventional nonnegative matrix factorization (NMF) methods cannot efficiently capture random properties of actual spectra because these methods assume that speech and noise spectrograms can be precisely represented by combining a small number of temporally invariant spectral patterns,...

In this paper, we propose the use of a novel feature set, i.e., modulation spectrogram for fricative classification. Modulation spectrogram gives 2-dimensional (i.e., 2-D) feature vector for each phoneme. Higher Order Singular Value Decomposition (HOSVD) is used to reduce the size of large dimensional feature vector obtained by modulation spectrogram. These features are then used to classify th...