Compare and contrast an algorithmic and convolution reverb.

Demonstrate the difference and the important features in both types of reverb.

Objectives

To compare and contrast an algorithmic and convolution reverb.

To provide you with an understanding of the differences and important features of both types of reverb.

My name is Subrina. I decided to teach this because as I was listeningto the video lecture on convolution, the word “space” kept comingback to me and I recall my own dance lessons and I often tell students,when you choreograph you want to listen to the space in the musicand it is within these spaces, you come up with yet another dancemove. So I felt that by teaching this, I will somehow obtain a brandnew understanding of space in the context of composing music. Please enjoy the presentation and thank you for reading.

Reverb

Before we try to understand algorithmic and

convolution reverb, let us explore reverb. What

is reverb?

Answer: Reverberation, or reverb for short,

refers to the way sound waves reflect off various

surfaces before reaching the listener's ear.

Reverb Explained

The diagram on the left shows one person (the sound source) speaking to another person in a small room. Although the sound is projected most strongly toward the listener, sound waves also project in other directions and bounce off the walls before reaching the listener. Sound waves can bounce backwards and forwards many times before they die out.

When sound waves reflect off walls, 2 things will happen:-

1. They take longer to reach the listener.2. They lose energy (get quieter) with

every bounce.

Reverb Explained:- The listener hears the initial sound directly from the source followed by

the reflected waves. The reflections are essentially a series of very fast echoes, although to be accurate, the term "echo" usually means a distinct and separate delayed sound. The echoes in reverberation are merged together so that the listener interprets reverb as a single effect.

In most rooms the reflected waves will scatter and be absorbed very quickly. People are seldom consciously aware of reverb, but subconsciously we all know the difference between "inside sound" and "outside sound". Outside locations, of course, have no walls and virtually no reverb unless you happen to be close to reflective surfaces.

Some rooms result in more reverb than others. The obvious example is a hall with large, smooth reflective walls. When the hall is empty, reverb is most pronounced. When the hall is full of people, they absorb a lot of sound waves so reverb is reduced.

Reverb, is it necessary?

Now that we have a better understanding of

what reverb means, the next question to ask

ourselves is, why do we use reverb?

Why do we use Reverb?

Reverb is most commonly used to put

elements of your song in a particular space like a small room or hall etc.

Reverb can also be used to add depth to certain elements in your mix, essentially making some elements sound further away, while the other elements with less or no reverb will be perceived as more upfront in the mix.

Why do we use Reverb?

Reverb can also be used as a creative effect or sound design tool. An example; setting up a hall verb on a return track (or parallel chain) set the dry/wet amount to 100% wet and place a sidechaincompressor or gate after the reverb. Side-chain the verb to the sound you are sending the reverb to (usually on lead synths or vocals) that way every time the sound is played the reverb closes or decreases in level, and when the sound stops playing, the reverb opens up.

Why do we use Reverb?

Reverb can also be used a tool for making pads. This means, you can take any sound that sounds boring, run it through a big hall reverb, with 90-100% wet with a long decay time and, the end result; a pad sound!

Algorithmic or Convolution

If you decide that you do not want to record your song in a reverberated space, then you will need to utilize your DAW and decide what type of reverb is suitable for your mix.

Your main choices:

Algorithmic

Convolution

Algorithmic vs Convolution

Algorithmic reverb creates a sense of space with a formula (like a digital synthesizer creates sound with a formula, an algorithmic reverb creates a sense of space with a formula). This simulating the impulse response that is applied to the sound signal to create the reverb effect on that sound signal

Algorithmic vs Convolution

Convolution reverb is taken from real rooms using multiple microphones to capture or ‘sample’ the acoustics of a room, capturing the complexities of real space. Then the sound you make is filtered through ‘impulse response’ generator to create an effect as if your sound was recorded in that room.

Algorithmic vs Convolution

• Convolution reverb is more like a sampler, used from recorded sound.

• Algorithmic is more like a digital synthesizer, creating the effects of space through formula.

Point to note: Convolution can sound more ‘real’ capturing the complexities of acoustics in a way that algorithm can’t quite generate.

• With algorithmic reverb, the algorithms are adding the reverb, so adjustments to the parameters can be made.

• Impulse response file of a convolution reverb, as it is sampled from a room, tends not to be as flexible.

• More complex• More control

• The convolution reverb can be useful when wanting to add more realness to software instruments (i.e. instruments that aren’t samples and have some natural noise)

• Algorithmic reverb can be used on natural samples to create interesting effects

Which one should you use?CPU power, how much do you want to use?

• Algorithmic reverb : requires lesser CPU power

• Convolution reverb: needs a lot of CPU power

Other than CPU power usage, what else should

you consider?

Which one should you use?

USE BOTH and consider the following when choosing: Use convolution reverb on solo instruments because they help fill out the

sound where there aren’t many other things going on in your track. Your mileage may vary, but that’s my general approach.

The more instruments you have the more you can get away with a strictly algorithmic reverb.

Use convolution reverb on instruments that aren’t sampled. Sampled instruments, even if sampled in a very dry environment, can often have a small amount of natural room in the sample. When you mix this with an algorithmic reverb, it can sound amazing.

Algorithmic reverbs on the other hand tend to excel at adding reverb to full mixes, or samples that already have some room recorded in.

Thank you for taking the time to read, I hope

you have found the information shared helpful.

It has certainly exposed me to aspects of

algorithmic and convolution reverbs I had never

known previously.