---
title: "Standing wave"
description: "A standing wave is the stationary interference pattern produced when an outgoing sound wave overlaps with its reflection from a vessel boundary. Pressure does not propagate; instead it oscillates in fixed positions of high amplitude (antinodes) separated by positions of zero amplitude (nodes) spaced one half-wavelength apart."
canonical_url: "https://sylio.co/glossary/standing-wave"
last_updated: "2026-06-28T02:29:22.708Z"
---

A **standing wave** is the stationary interference pattern produced when an outgoing sound wave overlaps with its reflection from a vessel boundary. Pressure does not propagate; instead it oscillates in fixed positions of high amplitude (antinodes) separated by positions of zero amplitude (nodes) spaced one half-[wavelength](/glossary/wavelength) apart.

## Implications for cleaning

Cleaning energy is delivered at antinodes; nodes do almost nothing. In a vessel small enough for standing waves to form, a single horn can leave predictable dead zones where deposits continue to build. Multi-horn array design, off-axis mounting and dithering the firing sequence are the practical countermeasures.

## When standing waves dominate

Standing-wave behaviour is strongest in vessels whose internal dimensions are comparable to the [wavelength](/glossary/wavelength). A 60 Hz horn (λ ≈ 5.7 m) interacts strongly with vessels of similar size; in much larger vessels the wave is too small to form clean standing patterns and the energy distribution is closer to a free-field projection.

## Related terms

- [Wavelength](/glossary/wavelength)
- [Resonance](/glossary/resonance)
- [Frequency](/glossary/frequency)