Acoustic_wave - Wikiparency

# Acoustic wave > On the **[[PORTAL_Acoustics|Acoustics]]** vibration spine · article face [[Acoustics]]. Microsim first, then the physics. ## Microsims — p5.js <div class="microsim-player"> <iframe src="https://editor.p5js.org/sciencenibber/full/90jeLsBsW" width="100%" height="620" frameborder="0" loading="lazy" sandbox="allow-scripts allow-same-origin" title="Acoustic wave — p5.js microsim"></iframe> </div> <div class="microsim-fallback"><em>Live p5.js microsim (desktop) · <a href="https://editor.p5js.org/sciencenibber/sketches/90jeLsBsW">open / fork the sketch in the p5.js editor</a></em></div> **Acoustic wave (p5.js).** A click-to-start point source emits radial pressure waves into a 4 m × 4 m field, rendered as a warm/cool grid that turns red where the medium is compressed and blue where it is rarefied. A 1D cross-section through the source shows the analytic profile p(x, t) = (A / √r) sin(k·r − ω·t), with a scale bar marking one wavelength. Three sliders control source frequency (40 Hz – 2 kHz), amplitude, and the medium (air at 343 m/s, water at 1480 m/s, steel at 5960 m/s); a sine oscillator plays the audio-band component as a pure tone, and a live readout reports c, λ, ω, and the nearest musical pitch. ## Overview An acoustic wave is a longitudinal disturbance — a propagating pattern of compressions and rarefactions in an elastic medium (air, water, a solid). It carries [[Energy|energy]] and momentum but no net mass transport. The defining relation is the [[Wave|wave]] equation, whose plane-wave and radial solutions both satisfy c = f·λ, where c is the speed of [[Sound|sound]] in the medium (343 m/s in air at 20 °C, ~1480 m/s in water, ~5960 m/s in [[Steel|steel]]), f is the source frequency, and λ is the resulting wavelength. The same equation governs sound in air, ultrasound in tissue, infrasound from earthquakes, and the acoustic phonons that carry heat in solids — what changes between contexts is the speed and the absorption. This microsim renders the radial wavefronts emitted by a single point source as p(r, t) = (A / r) · sin(k·r − ω·t), where k = ω/c is the wavenumber. The reader scrubs the source frequency and the medium (air / water / steel), watches the wavelength λ contract and dilate to keep c = f·λ, and simultaneously hears the audio-band component as a pure tone. A 1D cross-section beneath the field shows the pressure profile along a horizontal slice, and a live readout reports c, f, λ, and ω. The companion Sound microsim handles the particle-level compression / rarefaction picture; this one handles the propagation picture and the medium-dependent speed. ## On the Acoustics spine Neighbours on the vibration spine: [[Sound]] · [[Wave]] · [[Oscillation]] · [[Vibration]] · [[Mechanical_wave]] · [[Plane_wave]]. Bridge portal [[PORTAL_Acoustics]] · index [[PORTAL_INDEX]] · systems root [[PORTAL_Systems]].  **Microsim — three.js (Wikitube framework):** *Acoustic wave* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/acoustics/Acoustic_wave.html" data-title="Acoustic wave"></div> *Built from `MICROSIM_GUIDE/specs/acoustics/variants/Acoustic_wave.json`; part of the [[PORTAL_Acoustics|Acoustics portal]] spine (section sims and See-also variants).*  ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Acoustic_wave) : [Wikitube](https://en.wikitube.io/wiki/Acoustic_wave) --- *Repopulated 2026-08-05 · microsim-first transfer from legacy GENERATIVE lane · p5 sciencenibber/90jeLsBsW · 0 deletions.*