EQUIPMENT AND SUPPLIES NEEDED

• Mac computer with as big a monitor as possible (such as the iMacs in Wilson G20)

• casette player and CD player

• leads to connect the cassette and CD players to the computer

• batteries or AC adapters for players

• cassettes or CDs with animal (and other) sounds for display

• microphone with a mini phone plug

SET-UP

1.   Turn off and disconnect the cassette or CD player.

2.   REMOVE BATTERIES from the cassette and CD players.

3.   RETURN EVERYTHING to where you found it!

4.   Shut down the computer (or put it to sleep).

1.   There are two versions of WildSpectra ...

WildSpectraLive records and displays sounds in real time from a microphone, cassette player, or CD player.   After you stop recording, you can save the the recording as a digital sound file (aiff or wav format).

WildSpectra displays previously recorded digital sound files (aiff or wav files), including those recorded by WildSpectraLive.   It also has lots of options for displaying and analyzing sounds.

2.   Launch WildSpectraLive by double-clicking on the icon (incidently, what does that icon represent?)

4.   Options are presented in the menus at the top ...

Start with the default options -- except change the PANEL HEIGHT to 512 pixels ...
if you want a really big display!

5.   Basic controls are summarized in the panel at the bottom.

Apple-R -- start recording

Apple S -- stop recording

Notice that while recording you can change the intensity of the spectrogram
(Apple-X for darker, Apple-Z for lighter) ...

... and you can switch between spectrogram and waveform displays
(Apple-W toggles between them)

5.   After you have recorded a sound and stopped, you can use the menus to save it as a digital file
(aiff or wav) and then use WildSpectra to analyze it in various ways.

1.   After setting up WildSpectraLive, as above, play a tape or CD of bird songs.

2.   Default settings for WildSpectraLive often work well ...

Transform Size 256, Analysis Range 22050 Hz

4.   Can you find an example of a species that can produce two harmonically unrelated tones
at the same time (with the two halves of the syrinx working independently)
to produce a self-duet?

Try songs of Wood Thrush or Lapland Longspur ...

and be prepared to explain how to distinguish harmonics (integer multiples of a fundamental frequency) from harmonically unrelated tones (not multiples of a fundamental frequency).

1.   Connect the microphone to the computer, set up WildSpectraLive, as above, and then . . .

2.   Say something, like "ee . . . ay . . .ah . . . oh . . . oo".

The emphasized frequencies (or formants) in vowels result from resonance in the pharyngeal cavity (as modified by the tongue and jaw positions).

Compare a series of vowels, like those above, with a selection of consonants.   For instance, say the words "Wild Spectra" (emphasizing the consonants)!

3.   Compare an individual's voice at Transform Sizes 256 and 128

Pay close attention to the fine structure of the spectrogram near the baseline.

Transform size changes the temporal and frequency resolution of the spectral analysis.   With a larger transform size, we have lower temporal resolution but higher frequency resolution.

With higher temporal resolution (Transform Size = 128), you might find (especially with male voices) that the opening and closing of the vocal chords appear as distinct impulses (vertical lines) on the spectrogram.   With lower temporal resolution (Transform Size = 256 or 512), these impulses instead appear in the frequency domain as a series of narrowly spaced harmonics (horizontal lines).

What is the difference between male and female voices (on average)?   Is it a difference in fundamental frequency or is it a difference in pulse rates of the larynx?