Reverb: The Shape of a Room

Clap your hands in a cathedral. Sound hits every surface - stone walls, marble floor, vaulted ceiling - and bounces back thousands of times. Those reflections blur together into a wash of sound that fades slowly. That wash is reverb.

Early reflections and tail

The first reflections arrive quickly - they have bounced off the nearest walls. These early reflections tell your brain the size and shape of the space. After that, reflections pile up so densely they merge into a smooth tail that decays over time.

Impulse response

Record a room's response to a single sharp click - a balloon pop, a starter pistol. That recording captures everything about the room's acoustics. It is called an impulse response. You can apply it to any sound using convolution. The machine below generates a synthetic impulse response from random noise shaped by a decay curve.

Impulse response - what a room "sounds like"

The sharp spike on the left is the original sound. Everything after it is reflections - dense, chaotic, fading to silence. A short tail means a small, absorbent room. A long tail means a large, reflective space.

Small room vs large room

The shape of the decay tells you the size of the space. A cupboard's reverb dies almost instantly. A cathedral's reverb lingers for seconds.

Small room (fast decay)

Large room (slow decay)

Every space has a unique reverb. A tiled bathroom. A parking garage. A concrete stairwell. Recording studios spend serious money on acoustic treatment to control their room's reverb character. Some of the most famous recordings in history owe their sound to a specific room.

Machine 14 - Reverb

261.63

Waveform

Pitch

Freq 261.63 Hz

Volume

Volume -5.8 dB

Scale

Scale Snap

Arpeggiator

Arp

Rate 260 ms

Reverb

Size 2.2 s

Decay 10

Mix 70%

The three controls

Size - how large the virtual room is. A small size (0.2 s) sounds like a cupboard. A large size (4--5 s) sounds like a cathedral. The tail stretches out as the room grows.

Decay - how fast the reflections die out. Low decay = hard surfaces (marble, glass, concrete) that ring for ages. High decay = soft surfaces (carpet, curtains, foam) that swallow reflections quickly.

Mix - balance between dry signal and wet reverb. At 0% you hear only dry. At 100% you hear only reverb. In practice, 20--40% gives a natural sense of space without drowning the original.

Reverb and depth

Reverb makes things sound further away. The more reverb relative to the dry sound, the further back it sits in the mix. This is how mix engineers create depth - instruments with less reverb feel close and present; instruments with more reverb feel distant and atmospheric.

Try it

Turn on the arpeggiator with the reverb. Each note leaves a trail of reflections that blends into the next. Slower arps with long reverb tails create ambient washes. Faster arps with short reverb create a shimmering texture.

Types of reverb

Spring reverb - vibrates a metal spring inside guitar amps. Twangy, splashy sound.

Plate reverb - vibrates a large metal sheet. Smooth and bright, beloved in studios since the 1950s.

Algorithmic reverb - computes reflections mathematically in real time.

Convolution reverb - uses recorded impulse responses from real spaces. This machine uses a synthetic version of that technique.

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