WildSpectra and WildSpectraLive

for Mac OSX (PowerPC and Intel)

 

To open files, analyze sounds, and collect data ...
[ DOWNLOAD WILDSPECTRA ]
(current version 11 March 2008 -- 176 KB .sitx file)

To digitize files and to display real-time spectrograms ...
[ DOWNLOAD WILDSPECTRALIVE ]
(current version 3 March 2008 -- 136 KB .sitx file).

Hints for Getting Started . . . Technical Notes . . . Known Problems . . . Wiley's homepage

As usual, study the "Help!" items in the menus.   They are the manual for WildSpectra.

WildSpectra includes all the functions for opening files and analyzing them.   It will open AIFF, SD2, and WAV monoaural 16-bit files digitized at 44.1 or 22.05 kHz for up to 32 mins (170 MB).   This version cannot be used to record sounds or to display real-time spectrograms.

WildSpectraLive uses QuickTime functions to record sounds and to display real-time spectrograms while recording on any Mac with a processor speed greater than 800 MHz.

More functions are in the planning stage, so stay tuned!

 

Systems Known to Run WildSpectra and WildSpectraLive Successfully

  • Any PowerMac, iBook, PowerBook, PowerMac, Mac Mini, iMac ... PowerPC or Intel

  • 10.2 (Jaguar), 10.3 (Panther), 10.4 (Tiger), 10.5 (Leopard)

     

    Notes on Opening Files with WildSpectra

  • AIFF, SD2, and WAVE or WAV files should all open without problems

  • ... including WAVE/WAV files from digital recorders.

  • To open MP3 files, first convert them to WAVE or AIFF files (for instance, with iTunes).

     

    A Few Hints for Recording Sounds with WildSpectraLive

  • If you have problems recording sounds, make sure that you have used the Sound Preference Panel and the Speech Preference Panel to select an appropriate input.   Also check your connections.

  • Although some G3 Macs use an extended mini phone plug for sound input, a regular stereo mini phone plug also works (for best results connect the signal to both channels of the stereo plug).

  • Either line or monitor (headphone) outputs (usually about 500 and 8 ohms respectively) from tape decks, CD players, or mp3 players work well.

  • USB sound input devices also work well.   In this case, use the Preference Panels to select USB INPUT.   WildSpectra assumes that all input is 16-bit stereo at 44100 Hz.   Again connect the signal to both channels of a stereo input device.

  • For convenience during recording, the Levels window in WildSpectra shows the recording level and provides an over-load indicator.

  • The Amplitude (or oscillogram) Display also shows the actual levels of the input.   If the amplitudes extend the entire width of the panel in the display, you are over-loading the sound input device (the A/D converter in the computer or the USB A/D converter).

  • The controls for Spectrum Gain affect only the display (not the sound file in memory).   Use these controls to adjust the darkness of the spectrograms to suit your needs.   Notice that two key-combinations (APPLE-X and APPLE-Z) can be used to adjust the real-time spectrograms on the fly during recording.

  • Above all, study the menus to understand the many options in using WildSpectra.   If the menus are not self-evident, try one of the Help! items.   There is no manual for WildSpectra . . . we have failed in our purpose if you need one!

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    Some Technical Notes

  • The FFTs are calculated with a public-domain algorithm.

  • Each analysis uses a Hanning window (an inverted, scaled cosine function without a threshold).

  • Successive spectra overlap 50% to compensate for the effects of windowing.

  • The Amplitude Display shows the amplitudes of the signal (like an oscillogram).

  • The Spectrum Display shows the power spectra of the signal.

  • No filtering is included in the PowerMac sound input device nor in WildSpectra.   If your signal includes frequencies above the analysis bandwidth, you will have to use an external filter (or equlaizer) to avoid aliasing.

  • The vertical axis of a display always equals 1/2 the digitizing rate.   Any intercalated pixels are linearly interpolated between spectral amplitudes.

  • On the horizontal axis, one pixel always equals one-half of an analysis period:   0.5 * (transform size / digitizing rate).   The factor 0.5 is a result of the 50% overlap of successive analyses.   At transform size 256 and digitizing rate 44100, one analysis period equals 5.8 ms, and there are 344.6 spectra / second or 861 spectra in 2.5 seconds (the default width of the display window).

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    Known Limitations and Problems

  • See notes above on opening files and on recording and displaying real-time spectrograms!

  • Available memory affects how large a sound file you can open or save.   You can work with long (even very long) files if you have enough memory.   Memory requirements for both WildSpectra and WildSpectraLive are about 11 MB/minute of sound.   WildSpectra uses a lot of RAM and opening a big file can take some seconds, but once a file is open moving around in a file is fast.

  • Once again, study the Help! items in the menus for more information.

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    Who can identify the spectrogram in the logo?