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TFR Features
Signal Recording and Playback
TFR supports CD-quality (44.1 kHz, 16 bits/sample) recording and playback (mono
or stereo) on Windows-ready 16-bit audio systems. The recording and playback of
digital signals is done directly to/from disk, so signal length is limited only
by hard disk space.
Entire signals or selected parts of any signal can be played back from all editing
and analysis windows.
Comprehensive Signal Editing Capabilities
Any acoustic signal (mono or stereo) can be digitized, displayed, played back
in whole or in part, labeled, segmented, and saved to disk in whole or in part.
The editing environment is designed to allow quick segmentation of signals, and
you can amplify or attenuate segments digitally.
Signals can be tagged or labelled to facilitate reference and analysis. TFR's
Zoom facility provides precision down to the individual sample point and signals
can be scrolled left and right. Informative displays provide the duration, RMS
voltage and peak levels of any signal or windowed segment. As well, measured values
can be logged automatically to a disk file so they can be imported into spreadsheets
or wordprocessing packages for later analysis or to prepare reports.
Edited files are saved in Windows (.WAV) format. TFR automatically reads sampled
data files in .WAV, .ADF (audio data file), .aiff, .au, .bi, .bin, and ascii formats.
TFR's new Paste Editor makes it easy to concatenate two signals in whole or in
part, to create new signals.
Spectral Analysis
TFR provides a powerful suite of modern spectral analysis methods. Available analysis
methods include:
- Short-time Fourier transform
- Linear Predictive Coding (LPC) using autocorrelation
- Linear Predictive Coding (LPC) using Burg's method
- Linear Predictive Coding (LPC) using modified covariance
- High-resolution time and frequency analysis using the Cone-kernel TFR
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A sample
spectrogram calculated using the LPC modified covariance method, a 512
point analysis window with a 50% overlap (256 points). |
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Full control of key analysis parameters such as preemphasis, the type and size
of the analysis window, the degree of overlap, and the analysis order is provided
to you via pop-up menus. Overlap is adjustable from 0% to 99% and you have your
choice of analysis window type: Hanning, Hamming, Bartlett, or Rectangular. In
this way, you can easily vary the analysis parameters as the needs of your analysis
applications change. This detailed control of the analysis parameters relevant
to each method allows experienced users to go beyond the basics, by adjusting
parameters to optimize analyses for their own signals and applications. Tutorials
are available to guide new users through the analysis process.
Spectral Displays
The results of TFR analyses can be displayed as full-color spectrograms or as
"gray-scale" spectrograms. (Spectrograms are three-dimensional displays, with
time represented on the horizontal axis, frequency on the vertical axis, and amplitude
represented as the gray-level or as a color which varies according to the magnitude
of the signal component.). Frequency may be scaled in linear or log units. Available
displays include a true gray-scale or a "heat" color scale.
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A sample
grey-scale spectrogram displaying the statistics for the spectral slice
of an "s" fricative. |
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View |
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The
dual spectrogram mode allows a fully-interactive (playback and immediate
readout of time-frequency and amplitude coordinates of any point) display
of two signals, to facilitate comparison |
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View |
Any signal can be scrolled or zoomed, facilitating detailed examination of even
very long signals. Detailed measurements are available just by pointing the mouse
to the region of interest, and any spectrogram or spectrogram segment can be replayed
under mouse control so you can confirm the region under analysis by listening
to what you are examining or measuring.
The spectral display can be time-locked with a time-domain display (oscillogram)
of the same signal, and additional windows may be opened to display the results
of alternative spectral analyses of a signal, so that specific details of the
signal may be examined and compared. Alternatively, analyses of two or more signals
can be displayed for comparison, so that differences between the signals can be
examined in detail. Window tiling is fully suppported, so that you can display
any combination of spectrograms and time-synchronized waveforms that you wish
to place on your screen.
Measurement Capabilities
TFR offers a complete array of proven, useful measurements. Editing windows allow
precise measurement of signal and segment duration, and RMS amplitude. RMS amplitude
can be calculated, displayed for the entire signal and measured interactively.
The spectrogram displays allow instantaneous readouts of the time, amplitude and
frequency values for any desired point, and the spectrum (amplitude by frequency
profile) is displayed automatically for any point in time (spectral slice) or
specified time interval (average spectrum, including long-term average spectrum
(LTAS). Our Statistics module automatically calculates such key statistics as
the centroid (mean or first moment), variance, skewness and kurtosis of the frequency
in any window.
TFR supports both long term average measures over any desired time window, and
1/3 octave analyses. For speech signals, peak amplitude, formant center frequencies,
amplitudes and bandwidths are readily extracted. The formant tracking function
automatically extracts and displays these measures for the first six formants,
in an interactive spectrogram-type display from which mouse controlled measurement
and playback is available. These formant tracks can also be overlaid on the spectrogram
display, if desired.
TFR's pitch extraction system offers advanced methods for fundamental frequency
(F0) tracking, with results displayed as an interactive track. Like the amplitude
(RMS) track, the pitch track can be added to other displays (such as the spectrogram).
Our Pitch Statistics module automatically calculates measures such as mean pitch
and voice perturbation (jitter).
TFR allows you to control many aspects of the spectrogram display, including the
range of frequencies and amplitudes displayed, log vs. linear axes and normal
vs. 1/3 octave displays. Measured values in any display can be logged directly
to disk files that can be imported into spreadsheet and word processing programs
for further analysis or for report preparation.
Segment labelling and mouse-controlled playback of any segment of a displayed
signal provides assurance about just what is being measured. Extensive display,
zoom, and scrolling capabilities under mouse control help you find what you want
and measure it fast. Automatic logging to disk files that can be read by spreadsheet
and wordprocessing packages reduces clerical work and makes you more productive.
Additional measurements supported by TFR include Long-term average spectrum (LTAS)
and 1/3 octave analysis. The complete output from each spectral analysis can also
be saved for post processing with your own algorithms. Together, these features
give you a measurement capability that is second-to-none.
Printing
Printing and exporting the results of your analyses has never been easier: TFR
supports the full range of Windows utilities, allowing you to capture spectrogram
screens for use in other packages (e.g., CorelDraw or other drawing programs;
Word or WordPerfect; PowerPoint). You may also send screens directly to your laser
printer from TFR.
TFR Utilities
The TFR package includes numerous special utilities targeting specific needs identified
by customers. Some utilities permit you to append a specified amount of silence
to an audio file, to add noise to a file at a specified signal to noise ratio,
to interleave two mono files to create a stereo file, to ramp the start and end
of a file, and to replace labelled portions of a TFR file with noise at a specified
level. Other utilities let you flip a signal in time (end for end) or amplitude
(reverse phase), randomize phase, and add reverberation or other special effects.
CDROM databases
Interested in using standardized, CD-ROM databases? No problem. TFR makes it easy
for you to read databases such as NIST's TIMIT, the Oxford University Press Acoustic-Phonetic
Database, Kay's database of disordered speech and many others.
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TFR Demo |
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