Showing papers on "Spectrogram published in 1969"

Time‐variant spectra of violin tones

Abstract: Harmonic analyses of several violin tones have been performed by computer. Each sound is represented by a finite series of harmonic‐amplitude and phase‐spectrum components varying with time. Graphical representations of spectra being explored are: (1) individual plots of fundamental‐frequency harmonic amplitudes (both linear and dB), and relative phases as functions of time; (2) line‐spectra movies with harmonic amplitude changes slowed 20:1; (3) spectrograms with vertical frequency scale, horizontal time scale, and darkness indicating amplitude. Spectrum analysis can be performed synchronously with the fundamental or asynchronously at a base frequency much lower than the fundamental, with advantages for each method. Completeness of harmonic analysis is demonstrated by examples of tones resynthesized using smoothed versions of harmonic‐amplitude and pitch curves. For storage purposes, synthetic tones typically require 500 to 800 parameter‐time coordinates per 1 sec of sound. Over all, the violin tones ana...

Printed data to speech synthesizer using phoneme-pair comparison

Abstract: Machine for converting a text printed in literal characters into speech, comprising means for converting each literal character into a corresponding binary-coded character, means for comparing groups of a variable number of successive ones of said coded characters and for deriving therefrom the phonetic equivalent of any such group in the form of a coded phoneme, and means including an address matrix for deriving from any two consecutively appearing such coded phonemes the address of a corresponding coded word assembly in a coded phoneme-pair spectrogram store. In the latter store, each spectrogram is written in the form of an assembly of binary-coded words, which represents in digitalized form the short-time spectrogram of a corresponding phoneme pair. As soon as the above-mentioned address is found, the proper word assembly is selected and extracted from the store, and the bits in said words are used to successively control in time the operation of a plurality of oscillators in number equal to that of said words in said assembly, while a sound-reproducing means is simultaneously fed from all of said oscillators.

Method and apparatus for optical speech correlation

Abstract: A system for speech correlation which comprises a coherent light modulating system which accepts a two-dimensional array of information corresponding to a speech spectrogram and superimposes this information two dimensionally on the cross section of a coherent light beam. The correlator further comprises means for imaging the modulated beam on a series of comparison means which correspond to words stored in a library. Preferably, the means provided is capable of simultaneously producing multiple images of the input so as to enable simultaneous comparison. Finally, means are provided for indicating correlation between the input and one of the words in the library. The method embodiment of this invention preferably comprises the steps of modulating the two-dimensional cross section of a coherent beam with speech spectrogram information, the depth of the modulation corresponding to intensity in the spectrogram. The method also includes the steps of comparing the modulated beam with a set of masks corresponding to a predetermined vocabulary and producing an indication whenever correlation occurs between the input and one of the words in the vocabulary.

Digitalized Sound Spectrograph Using FFT and Multiprint Techniques

Abstract: In the history of speech research, sound spectrographs are playing the role of an almost invaluable tool. Besides the many advantages of these instruments, some of their limitations have also become evident. Quite a few of these are a direct consequence of the utilization of analog techniques in these devices. The present paper tries to show that digital‐processing techniques allow to implement a spectrographic system much more powerful than its analog counterpart. Its hardware consists of a general‐purpose computer adapted to accept digitally encoded speech signals, and a standard chain printer. The short‐time power spectra are computed utilizing the fast Fourier transform algorithm. Spectrograms with eight gray levels can be generated by multiprinting adequate sequences of characters out of the basic 48‐character set. The necessary computer programs are sufficiently simple to be easily tailored to the specific needs of any particular investigation. Wherever digital processing is used in speech research, the approach described exhibits its greatest advantages. The digital spectrograph can then be seen to constitute an organic part of the total software system being a subroutine that may be called whenever needed.

VLF and LF Emissions at Auroral Latitudes

Abstract: Naturally occurring electromagnetic noise at very low and low frequencies generated in the ionosphere or the magnetosphere is called VLF and LF emission. There are different types of noise classified according to their shape in a frequency—time spectrogram (Gallet, 1959), but they can all be characterized as either discrete noise, which has a clear structure in the spectrogram, or hiss, which has no or very little structure and so resembles white noise.

Catalytic Factors in Speech Perception

Abstract: Speech from which all formant information except the second formant frequency has been removed by filtering and infinite clipping is still highly intelligible. Spectrograms of such speech exhibit a normal formant band and higher “harmonic” bands representing clipping distortion. This spectral configuration was approximated by use of a multivibrator whose period was controlled by the output of a second formant tracker. A voice operated gate was interposed between the multivibrator and the output terminals of the device. The resulting signal, although possessing a spectrogram closely comparable to that of the filtered‐clipped speech already mentioned, is not at all speechlike and has zero intelligibility. Addition of random noise or a signal repetitive at typical glottal rates to the multivibrator control signal renders the signal speechlike and somewhat intelligible. It appears that the perturbations in individual multivibrator periods caused by the noise or repetitive signal are catalytic factors which en...