Tremolo Lab – Explore Amplitude Modulation (Pulsing Sound)

Tremolo Lab is an interactive sound tool that lets students hear and see how a steady tone can be made to pulse. This effect is called tremolo, and it happens when the volume of a sound rises and falls repeatedly.

In this lab, one main tone (called the carrier) plays continuously. A second, much slower vibration controls the volume of that tone. This process is called amplitude modulation — the sound’s loudness is being modulated (changed) over time.

Students can adjust:

• Pitch – the frequency of the main tone
• Tremolo Rate – how fast the volume pulses (in Hz)
• Depth – how strong the pulsing effect is
• Base Volume – the overall loudness

A slow rate creates a gentle, wave-like pulsing. A faster rate creates a rapid, shimmering effect. Increasing the depth makes the sound pulse more dramatically, while lowering the depth makes the change more subtle.

The waveform display shows how the steady tone changes shape as its volume rises and falls. Students can see the larger “envelope” pattern wrapped around the smaller sound wave.

Concepts students explore:

• Amplitude as loudness
• Modulation as a repeating change over time
• The difference between pitch changes and volume changes
• How electronic instruments and guitar pedals create tremolo effects

Tremolo Lab works well in music and STEM lessons about waves and sound. It helps students understand that sound can be shaped not only by pitch, but also by how its loudness changes over time.