Harmonics Lab – Build a Sound by Stacking Waves

Harmonics Lab is an interactive sound exploration tool that helps students understand why different instruments sound different. Instead of simply choosing a sound, students actually build a tone by combining vibrations.

Every musical sound begins with a main vibration called the fundamental frequency. This determines the pitch — how high or low the sound is. In Harmonics Lab, students start with one smooth, pure tone and then gradually add additional vibrations called harmonics.

A harmonic is a vibration that moves faster than the main pitch at exact whole-number multiples. For example, if the main pitch is 220 Hz:

• 2× harmonic vibrates twice as fast (440 Hz)
• 3× harmonic vibrates three times as fast (660 Hz)
• 4× harmonic vibrates four times as fast (880 Hz)
• 5× harmonic vibrates five times as fast (1100 Hz)

When these harmonics are added together, the sound becomes fuller and more complex. Students can adjust the Frequency slider to change pitch, then use the 2×–5× sliders to increase or decrease each harmonic. As they experiment, they will both hear the sound change and see the waveform change in real time on the oscilloscope display.

With only the fundamental tone, the sound is smooth and clear. As harmonics are added, the tone becomes brighter, richer, or buzzier. This models how real instruments work. A flute has fewer strong harmonics and sounds smooth. A trumpet or electric guitar contains many stronger harmonics and sounds bright or powerful.

Concepts students explore:

• Frequency determines pitch (higher frequency = higher sound)
• Sound waves combine to form complex tones
• Adding harmonics changes tone quality (timbre)
• Waveform shape reflects the mixture of vibrations
• Real-world instruments are built from multiple simultaneous vibrations

Harmonics Lab supports music instruction, physical science units on sound and vibration, and STEM exploration. It encourages experimentation and inquiry, allowing students to discover how sound is constructed rather than simply hearing a finished tone.