The Full Soundscape

Infra- and Ultrasonics

The “good” distortion
completes the music.

“Though this be madness, yet there is method in’t.”
— W. Shakespeare, Hamlet

Think about it: what if all the world’s music were like an over-compressed MP3 – squeezed into 20 Hz to 20.5 kHz. If you could only hear up to 20 kHz, it would be like eating a pizza without the cheese.

In reality, instruments don’t stop at the 20 Hz–20 kHz range. For example, measurable harmonics from 40 to 80 kHz can be present in the spectrum of a violin, cymbal, or oboe. And while we may not hear them the way a dog, cat, or tarantula does with their hearing organs (yes, they can detect ultrasound), our brain and body still respond to them.

A fuller soundscape

Infra- and ultrasonic frequencies are like the salt in a soup. You don’t always notice them directly, but they reveal the true tone and body of instruments.

Brain response

Research has shown that these frequency ranges affect brain activity, making music feel more natural.

Emotional closeness

These frequencies are like a VIP ticket to a concert. You don’t see them, you don’t consciously hear them – but they bring you closer to the performance.

The world we can sense,

even if we cannot hear it directly

Infra- and ultrasonics

Our ears don’t directly perceive content above 20 kHz.. Yet these frequencies can interact with the audible range through intermodulation, adding to the sense of realism.

Meyer, J., & Elko, G. (2000). Ultrasonic components in musical instruments. Journal of the Acoustical Society of America.

Intermodulation

When ultrasonic components are present in the system, nonlinearities can cause them to reappear in the audible range. For example, the interaction of 30 kHz and 35 kHz signals can create an audible 5 kHz component.

Fastl, H., & Zwicker, E. (2007). Psychoacoustics: Facts and Models. Springer.

The body senses sound

This may sound extreme, but think of sounds below 20 Hz, which we can only perceive with our bodies. We’ve all experienced this. Some studies suggest the same applies to the upper ultrasonic range. These sounds don’t reach us through hearing, but rather create a physical sensation. The energy of ultrasound can resonate in the tissues and on the surface of the skin.

Kuribayashi, R. et al. (2017) – ultrasonic range and brain activity and Oohashi, T. et al. (2000). Inaudible high-frequency sounds affect brain activity: hypersonic effect.

These effects happen naturally in many high-end systems. We consciously aim for them and take the ultrasonic range into account during design.

The result?

A richer, more authentic soundscape. Natural distortion is not a flaw — it’s an opportunity.