---
title: "Fundamental frequency"
description: "The fundamental frequency is the lowest natural resonant frequency of a vibrating system. For a sonic horn it is the nameplate frequency at which the diaphragm or piston is designed to oscillate and at which the horn delivers its rated SPL. A horn marked \"60 Hz\" produces a fundamental at 60 Hz plus a series of harmonics at integer multiples (120 Hz, 180 Hz, etc.)."
canonical_url: "https://sylio.co/glossary/fundamental-frequency"
last_updated: "2026-06-28T02:29:22.916Z"
---

The **fundamental frequency** is the lowest natural resonant frequency of a vibrating system. For a [sonic horn](/glossary/sonic-horn) it is the nameplate frequency at which the [diaphragm](/glossary/diaphragm-horn) or piston is designed to oscillate and at which the horn delivers its rated [SPL](/glossary/sound-pressure-level). A horn marked "60 Hz" produces a fundamental at 60 Hz plus a series of [harmonics](/glossary/harmonic) at integer multiples (120 Hz, 180 Hz, etc.).

## Why it is the published number

Acoustic energy is concentrated at the fundamental. Harmonics carry progressively less energy. Selection charts, sizing tools and ROI calculations all use the fundamental as the reference. When tuning a multi-horn array, the fundamentals are chosen to avoid coincidence with vessel-tube [resonance](/glossary/resonance) modes that could cause unwanted vibration.

## Related terms

- [Frequency](/glossary/frequency)
- [Harmonic](/glossary/harmonic)
- [Resonance](/glossary/resonance)
- [Diaphragm horn](/glossary/diaphragm-horn)