Understanding Frequency and Wavelength in Sound

When we talk about sound—whether it's music, dialogue, or thunder—we're really talking about waves moving through the air. Two key terms you’ll hear a lot are frequency and wavelength. Let’s break them down.

 What Is Frequency?

Frequency is how many times a sound wave repeats in one second.

• Measured in Hertz (Hz)

• 1 Hz = 1 cycle per second

• Higher frequency = higher pitch (like a whistle)

• Lower frequency = lower pitch (like a bass drum)

What Is Wavelength?

Wavelength is the physical length of one full cycle of a sound wave—measured in meters (or feet).

It depends on both the speed of sound and the frequency:

​

• The speed of sound in air is roughly 343 meters/second (or 1,125 feet/second).

• Lower frequencies have longer wavelengths.

• Higher frequencies have shorter wavelengths.

Why It Matters for Audio

Understanding frequency and wavelength helps with:

• Speaker placement: Lower frequencies wrap around obstacles; higher ones are directional.

• Room acoustics: Long wavelengths (bass) easily cause standing waves and nulls.

• Treatment choices: You need deep absorbers for low frequencies. 40 Hz has a wavelength of 8.5 meters (28 feet). It takes lots of material to make a difference at this frequency.