Domain: Humanities and Social Sciences — Linguistics
Target concept: Spectral Visualization Comparison of Vowel and Stop Consonant Sounds

Video generation prompt: A speaker uses speech analysis software with a real-time spectrogram, continuously produces a vowel into the microphone, then pauses briefly, and subsequently produces a stop consonant.

Evaluation guide:
(i) Target concept: Real-time spectrographic distinction between vowel production (steady horizontal formant bands) and stop-consonant production (silence followed by a broadband burst), as a direct visual consequence of the speaker's own articulation and voice.
Minimum mechanism: The vocal tract's configuration must causally drive the spectrogram's output, synchronized to the speaker's real audio at each phase: a sustained, open vocal tract yields horizontal formant banding; a complete closure yields a flat, silent display; an abrupt release yields a sudden, dense broadband burst. The displayed pattern is expected to track genuine acoustic output phase-by-phase, not merely appear plausible independent of what the speaker is actually producing.
(ii)Storyline: [0–2s] Speaker sustains a vowel with an open, unchanging mouth shape → spectrogram shows steady horizontal bands; [2–3s] Speaker closes the mouth and holds still → spectrogram shows a flat, empty display; [3–4s] Speaker releases the closure → spectrogram shows a sudden burst of dense vertical marks; all three phases occur in one fixed shot with no cuts, with the spectrogram's changes driven by and synchronized to the speaker's real articulation and audio output at each phase.

Manual:
Experimental Procedure
1. Speaker faces forward, holding a functional microphone.
2. Speaker produces a sustained vowel (e.g., /a/) for ~2 seconds while spectrogram updates in real time.
3. Speaker pauses completely (mouth closed, no airflow) for ~1 second — spectrogram shows flat silence.
4. Speaker produces a voiceless stop consonant (e.g., /p/ or /t/) — spectrogram shows abrupt broadband burst.
Observation of Experimental Phenomena
- Vowel phase: continuous horizontal formant bands on spectrogram; speaker holds open mouth posture.
- Pause phase: flat, empty spectrogram baseline; speaker’s mouth fully closed and motionless.
- Stop consonant phase: sharp vertical energy burst on spectrogram; speaker performs visible closure-then-release.
Summary of Experimental Principles
Vowels produce resonant, periodic energy visualized as stable horizontal formant bands. Stop consonants involve complete vocal tract closure followed by sudden release, generating a transient, aperiodic broadband burst — separable from vowels by silence gap and spectral shape.

Prompt Grounding rubric:
level_1: No spectrogram display appears in the video, or no speaker is shown, or no microphone is shown, or the video does not show a vowel sound followed by a pause followed by a stop consonant in that order.
level_2: A spectrogram display is shown but never appears to update or respond to anything; the speaker and microphone are shown but the speaker never appears to vocalize; the vowel and stop-consonant actions are shown without any visible pause separating them.
level_3: A spectrogram display is shown updating on screen, a speaker is shown facing a microphone, the speaker's mouth is held open for a vowel, then closes for a visible pause, then opens again briefly for a stop consonant; the three stages occur once each, in this order, within a single continuous shot.
level_4: Everything in the 3-point level holds, and in addition the speaker's mouth shape visibly matches the stage being performed (held open during the vowel stage, closed during the pause, a brief closure-then-release during the stop-consonant stage), the microphone stays in the same place in frame throughout, and the spectrogram display remains on screen and visible for all three stages without disappearing.
level_5: Everything in the 4-point level holds, and in addition there is no cut, jump, or change of camera angle from the vowel stage through the stop-consonant stage, the lighting and framing of the speaker, microphone, and spectrogram stay the same throughout, and no extra people, hands, or objects enter the frame at any point.

Scientific and Causal Correctness rubric:
level_1: The spectrogram shows the same pattern for the vowel and for the stop consonant (e.g., both look like flat silence, or both look like noise, or both look like steady bands), so there is no visible link between what the speaker's mouth is doing and what the display shows.
level_2: The spectrogram's response is swapped or wrong for what's happening: the vowel stage shows noise instead of steady bands, the stop-consonant stage shows steady bands instead of a burst, the pause stage shows visible energy on the display, or the stop consonant never produces a burst-and-silence pattern at all.
level_3: During the vowel stage the spectrogram shows continuous horizontal bands; during the pause it shows a flat, empty display; during the stop-consonant stage it shows a sudden burst of energy; and each of these display changes lines up with the matching stage of the speaker's mouth movement.
level_4: Everything in the 3-point level holds, and in addition the vowel stage's bands look stacked in at least two distinct horizontal layers rather than a single blurry stripe, the pause stage's display is essentially empty and dark rather than faintly active, and the stop-consonant stage shows both the silence and the following burst rather than just one of the two, with no vowel-like horizontal banding visibly overlapping into the stop-consonant stage.
level_5: Everything in the 4-point level holds, and in addition the transition from the pause's empty display straight into the stop-consonant's burst happens without any leftover horizontal banding lingering into that burst, and the timing of the display's changes matches the timing of the speaker's mouth closing and releasing rather than changing well before or well after the mouth does.

Spatiotemporal Consistency rubric:
level_1: The spectrogram display freezes, jumps back, or resets partway through; the speaker or the microphone disappears and reappears; the lighting suddenly changes; the camera cuts or pans between the vowel, pause, and stop-consonant stages.
level_2: The spectrogram's scrolling skips or stutters; the speaker's head or mouth position jumps to a new spot without a visible motion connecting the two positions; the microphone visibly moves or rotates; the background flickers or changes shape.
level_3: The spectrogram scrolls smoothly from left to right with no stutter, reset, or skip; the speaker stays fully in frame; the microphone stays in the same place and orientation; the room lighting and background stay the same; the speaker's mouth movement looks physically continuous within each stage.
level_4: Everything in the 3-point level holds, and in addition the spectrogram's scroll speed looks the same across all three stages, the speaker's head stays still during the pause with no large visible movement, the microphone's apparent size and angle in frame don't shift, and neither the spectrogram nor the speaker's face shows visible warping or stutter between frames.
level_5: Everything in the 4-point level holds, and in addition the spectrogram's baseline stays level across the whole video with no visible vertical drift, the speaker's mouth remains visibly closed and motionless throughout the pause, the microphone housing does not visibly move or shake at any point, and no moving element in the shot shows visible strobing or ghosting.