The generated files are mono 16-bit PCM at 22,050 samples/s and 2.40 seconds long. Four separate 0.12-second events begin at 0.10, 0.60, 1.10, 1.60 seconds. Each has a 10 ms fade at both ends and a quiet gap before the next event. A uses only a 330 Hz sine component; B uses 330 Hz plus a 990 Hz third harmonic. Thus the stated fundamental is 330 Hz for both recipes, while their waveforms differ. This is an original technical contrast, not a named instrument, voice, song, culture, or guaranteed perceptual category. Different programmed component amplitudes and digital peaks do not guarantee equal perceived loudness on a speaker.
All three are candidate files, not cleared for classroom playback until a human educator listens to each on intended equipment, checks comfortable volume, distortion/harshness and child choice, and retains the full no-sound route. They are not set to autoplay. No child recording or data is captured.
| Candidate | Exact event transcript | Complete quiet source-plan route |
|---|---|---|
| cue-a-only.wav (playback review held) | A pure 330 Hz at 0.10, 0.60, 1.10 and 1.60 s; each event lasts 0.12 s; quiet between and after. | B one-source board: four broad A circles on fixed numbered places; explain that one recipe is planned throughout. |
| cue-b-only.wav (playback review held) | B 330 Hz fundamental plus 990 Hz harmonic at 0.10, 0.60, 1.10 and 1.60 s; each event lasts 0.12 s; quiet between and after. | Use the A two-recipe legend and place four striped B cards on the B board. |
| cue-aabb.wav (playback review held) | A at 0.10 and 0.60 s; B at 1.10 and 1.60 s. A is 330 Hz only; B is 330+990 Hz. Each 0.12 s event is separate, with quiet gaps. | C switch board: A A B B, with a broad change marker at the 2→3 boundary. |
The educator's human review decides whether any cue is tolerable and useful. Opening or generating a file does not show that a child heard a difference, can name a timbre by ear, reproduced it, or wanted to listen.