Domain: Humanities and Social Sciences — Linguistics
Target concept: Visualizing the Dynamic Changes of Speech Amplitude (Intensity) in the Time Domain

Video generation prompt: A person produces a brief consonant sound (/t/) into a microphone connected to a computer, with the resulting audio waveform displayed on the screen. The speaker repeats the /t/ sound several times, moving from a soft voice to a loud voice.

Evaluation guide:
Target concept: Real-time mapping of speech intensity (acoustic amplitude) onto vertical deflection of a time-domain waveform, using a controlled, brief, voiceless plosive (/t/) as probe. Minimum mechanistic assumptions: (i) microphone transduces air pressure → voltage roughly linearly; (ii) the waveform display renders voltage magnitude as trace height on a fixed vertical scale; (iii) speaker's subglottal pressure modulates burst amplitude across successive repetitions without altering the brief articulatory timing of any single /t/. Phased storyline: (1) Silence baseline; (2) speaker prepares the first /t/ (lips closed, tongue tip raised, with no visible output yet); (3) a short sequence of /t/ bursts follows, each with its own quick release and a brief return to a quiet baseline in between; (4) successive bursts grow taller on the display as the speaker's effort increases from soft to loud; (5) after the loudest burst, the trace decays back to silence. Visibility constraints: Must show the speaker's mouth (for /t/ release verification), the microphone (for source-path validity), and the full waveform display (for amplitude-height correlation); no occlusion; frontal, well-lit, static framing.

Manual:
I. Basic Demonstration Information
Demonstration Title: Visualizing Dynamic Speech Amplitude Changes in Time Domain (/t/ Intensity Ramp)
Subject: Linguistics - Phonetics - Acoustic Analysis
Demonstration Purpose: To visualize how speech amplitude (intensity) varies in real time across a short series of brief voiceless plosive /t/ bursts, as the speaker modulates volume from soft to loud; to train recognition of amplitude-height correspondence on waveform; to ground phonetic concepts in observable acoustic signal.

II. Demonstration Carrier/Equipment
Core Carrier: Human speaker (adult, native speaker, front-facing, neutral expression)
Auxiliary Equipment: Wired condenser microphone (visible grille, USB/XLR cable), laptop/desktop with audio input enabled, real-time waveform visualization software (e.g., Audacity in Oscilloscope mode or custom oscilloscope UI), plain background, even lighting.

III. Demonstration Content Description
Layout: Speaker seated, microphone centered 15 cm from lips, laptop screen visible beside or behind speaker. Software window occupies full screen, black background, single-color waveform trace (e.g., green), fixed vertical scale (no auto-gain), horizontal time axis scrolling left-to-right at constant speed.
State Control: Speaker produces a short series of isolated /t/ bursts—no vowel, no breathiness, no voicing—starting soft and growing progressively louder across the clip, with a brief quiet gap between each burst. No head movement, no secondary articulations.
Comparison Baseline: Waveform must show: (a) silence baseline before the first /t/; (b) a sharp transient burst at each /t/ release; (c) each successive burst taller than the last, showing a monotonic increase in peak amplitude across the sequence; (d) a brief return to a quiet baseline between bursts, and full return to silence at the end—confirming brevity and dynamic control.

IV. Observation of Core Phenomena
Soft Phase: The earliest /t/ bursts show small-amplitude, narrow spikes (~0.1 V peak, normalized), minimal energy spread.
Loud Phase: Later /t/ bursts, using the same articulation, show larger-amplitude spikes (~0.3 V peak, normalized) — roughly three times the soft-phase peak height — with higher RMS intensity.
Real-Time Update: The waveform trace scrolls smoothly without freezing; each burst's peak height grows relative to the previous one, tracking the speaker's increasing effort across the sequence.
Visual Feature Recognition: Amplitude = vertical height of waveform deflection from zero line; time = horizontal position; burst sharpness confirms /t/ identity; the monotonic increase in peak height across bursts confirms the volume ramp.

V. Summary of Key Knowledge Points and Principles
Core Concept: Speech amplitude (intensity) in time domain is directly represented as instantaneous voltage magnitude of the acoustic waveform; it reflects aerodynamic energy and glottal/supraglottal configuration.
Principle of Visualization: Real-time oscilloscopic display transforms abstract auditory perception into concrete spatial magnitude—enabling direct observation of prosodic and articulatory control.
Phonetic Significance: /t/ is ideal for amplitude study—it has no inherent voicing, minimal duration, and burst energy highly sensitive to subglottal pressure, making amplitude modulation clearly visible and interpretable across repeated productions.

Prompt Grounding rubric:
level_1: No microphone, no person speaking, no computer or screen present, or the screen shows unrelated content (e.g., a text document, a static image, a music player interface); no waveform of any kind is displayed; no /t/-like consonant sound is attempted; no soft-to-loud volume change is attempted.
level_2: A person, a microphone, and a screen are all present, but the screen shows no waveform, a frozen waveform, or a waveform unrelated to the speech (e.g., a decorative animation); or the speaker produces sound but not a plosive /t/-type sound (e.g., a vowel, humming, or silence); or the requested soft-to-loud progression is missing or reversed (loud-to-soft).
level_3: The person speaks close to the microphone; the screen shows a horizontal, scrolling time-domain waveform; a brief /t/-like burst is audibly and visibly attempted multiple times; the waveform height changes somewhat as the speaker's effort increases, but the display looks inconsistent: e.g., the vertical scale appears to jump or reset partway through, or there is no obvious live-refresh motion (a moving cursor, a scrolling trace) to indicate the display is running in real time.
level_4: The person produces a clear, short /t/ articulation (visible lip closure followed by a quick release, with no following vowel) several times; the microphone is visibly cabled to a laptop or desktop; the screen shows a clean, single-color waveform trace that scrolls continuously; the waveform's peak height visibly grows from short, soft-looking bursts to tall, loud-looking bursts across the clip; the waveform's resting line stays level between bursts; and no unrelated toolbar, playback controls, or spectrum view appear on screen.
level_5: All of the following hold together: (i) the speaker faces the camera, lips close briefly then release for each /t/, with no vowel or humming sound following the release; (ii) a corded microphone is visibly connected by cable to the computer; (iii) the screen shows a minimalist, single-trace waveform on a plain background with a fixed vertical scale that does not visibly auto-rescale, and a steadily scrolling time axis; (iv) the first /t/ burst is short and low on the display, and later bursts grow taller as the speaker gets louder, with the final burst ending up roughly three times taller than the first; (v) the waveform keeps updating smoothly for the whole clip, with no freezing, flicker, or dropped frames.

Scientific and Causal Correctness rubric:
level_1: The waveform behaves opposite to acoustics: for example, the display gets visibly smaller as the speaker gets louder, or a /t/ is produced with continuous voicing or a trailing vowel rather than a brief burst; the microphone appears turned away from the speaker or unplugged; the display shows a frequency-based view (e.g., a spectrogram or a bar-graph spectrum) instead of an amplitude-vs-time trace.
level_2: The waveform updates, but not causally: its rise appears before the speaker's mouth moves, or the lips release with no corresponding change on screen; the burst height jumps in one abrupt step rather than growing gradually over the soft-to-loud sequence; the trace shows a persistent hum or a flat-topped (clipped) burst inconsistent with a clean, brief /t/.
level_3: Mouth movement visibly precedes each waveform burst, and burst height grows as the speaker gets louder, but with clear rough edges: the baseline appears to drift up or down between bursts; a burst looks like a broad, rounded hump rather than a short spike; the difference between the softest and loudest burst looks implausibly extreme for a spoken /t/; or the display never shows a quiet resting line between bursts.
level_4: The physics reads as coherent: each /t/ appears as a narrow, sharp spike right at the start of a burst rather than a slow hump; burst height grows smoothly from soft to loud without visible steps; the trace returns to a quiet, near-flat line between bursts, consistent with /t/ being a brief sound; and the timing looks causal throughout: lip release visibly precedes each waveform spike, with no lag a viewer would notice.
level_5: All of the following hold: (i) each /t/ burst looks sharp and brief against the surrounding quiet baseline, with no trailing hum, consistent with a voiceless burst rather than a sustained vowel; (ii) burst height grows in clear, even proportion to how loud the speaker appears to be speaking, not in sudden jumps; (iii) by eye, the loudest burst looks roughly three times taller than the softest burst, matching a soft-to-loud speech range that stays plausible for spoken volume rather than an extreme, unrealistic swing; (iv) the trace looks clean, without obvious smoothing that rounds off burst edges or compression that flattens the height differences; (v) the causal chain is visually unbroken across the whole clip: lip release, then immediate waveform spike, then a brief elevated stretch, then decay back to the quiet baseline.

Spatiotemporal Consistency rubric:
level_1: The speaker, microphone, and screen appear disconnected from each other: e.g., they belong to shots that don't match, the screen appears to float without a visible surface holding it, the waveform is drawn as a rotated or tilted 3-D shape rather than a flat trace, the time axis scrolls right-to-left, or the speaker's lips are seen opening only after the waveform has already spiked.
level_2: The spatial and timing relationships are shaky: the microphone is not aimed toward the mouth, the speaker's head moves erratically between bursts, the waveform visibly lags well behind the mouth movement or stutters, the scroll speed is uneven, or more than one distinct sound is produced where a single brief /t/ was expected.
level_3: The microphone stays close to and roughly facing the mouth, the waveform scrolls at a steady pace, and the speaker holds a mostly neutral posture, but there are small flaws: the head drifts slightly during the loud phase (changing mic distance), the waveform's time axis has no visible scale reference, or a burst's peak looks noticeably offset from the moment of lip release rather than lining up with it.
level_4: The scene holds together well: the camera keeps the speaker's face, the microphone, and the screen in one continuous shot without cuts; the microphone stays at a steady distance from the lips throughout; the waveform scrolls smoothly at a constant, unchanging rate; each burst's peak visibly lines up with the corresponding lip release with no noticeable delay; and the lighting on the speaker's face and the screen looks steady rather than flickering or shifting.
level_5: Everything above holds, plus: the camera appears rock-steady with no drift or handheld wobble; the microphone and computer look physically linked, with a visible cable and no slack suggesting a cut; the speaker's articulation looks anatomically plausible for /t/ (tongue-tip contact behind the teeth, a quick release, no exaggerated jaw drop or added vowel); the clip contains a clearly bounded sequence of /t/ bursts that plays out over a short, believable stretch, with the amplitude ramp occupying that same stretch rather than a separate portion of the clip; motion of the lips, microphone, and waveform trace all looks fluid with no stutter; and the whole scene shares one consistent lighting look, with shadows and highlights on the mic and laptop that don't shift or jump.