Acoustic differences between reverb spaces
Hall reverb simulates a large concert hall, with a long pre-delay (30-100ms before reflections arrive), dense early reflections, and a long decay time (2-4+ seconds). It creates the sense of space and grandeur, ideal for orchestral vocals and pianos. Plate reverb, created historically by vibrating a metal plate, has a shorter decay (1-2 seconds), dense reflections, and a characteristic bright, colored frequency response. It became the standard for studio vocals and drums because it adds size without washing out detail.
Spring reverb (found in guitar amplifiers) has a distinctive metallic ringing and very short decay. Room reverb simulates small studios or bathrooms, with very early reflections and short decay (under 1 second). It's useful for adding natural ambience without overwhelming a mix. Each physical space's reverb is defined by its decay time at different frequencies (a large hall's high frequencies die faster than lows, for example), which digital models attempt to capture.
Using reverb type to shape vocal and instrumental tone
Vocal placement often uses a subtle plate reverb (30-40% wet on an aux) to add size without losing intelligibility. A 2-3 second hall reverb at the same level would wash out the vocal. Drums benefit from short, bright room or plate reverbs to add kit cohesion without smearing transients. A lead guitar solo might sit in a longer hall reverb to sound more epic, while a bass typically needs minimal reverb to preserve clarity.
The balance between decay time and pre-delay defines reverb character. A long pre-delay (100ms+) with a medium decay creates obvious space and separation (often used on snare). A short pre-delay (5-15ms) with a moderate decay creates a glued, cohesive space (typical of vocal reverb). Different decay rates at different frequencies (high-frequency absorption) mimic real rooms and sound more transparent than artificially uniform reverbs, which is why convolution reverbs (recordings of real spaces) are prized in critical recording contexts.