“Just put some reverb on it.”
That request just pisses me off. What reverb? Which style? Hall? Room? Plate? Chamber? Spring? Tunnel? Cave? Well? Gated? Phased? Flanged? Real Space? Analog? Digital? Plug In?
There are so many choices that it can be daunting to pick the right reverb for the right job.
The many considerations needed to decide which reverb to use will be discussed in this article: I will present the points that I use to determine what reverb I employ in the mix process, that conveys the feeling for the particular emotion I wish to invoke in the listener. I will also discuss the many types of natural reverb and reverb simulators that exist in today’s world of music production.
Reverb is defined by the Merriam-Webster dictionary as:
: a sound that echoes
: an effect or result that is not wanted
I think this is a lame definition. Reverb is a sound that echoes, but the echoes that create reverberation are extremely complex – from the onset of the initial reflection to the last heard decay is a multitude of echoes that have variations in time, repetition and frequency response.
Secondly, in the world of mixing, reverb is definitely a sound that is wanted and useful in the creation of a wonderful listening experience!
The type of reverb depends on the size and shape of the room that the sound echoes in. A square room provides many less reflective surfaces than a cathedral. The material of the reflective surface determines the frequency response of the initial reflections and subsequent echoes that result in the tail or length of the reverb. The harder the surface, and the more surface angles and lengths of the room, the longer the repetition of echoes occur, resulting in a longer tail or reverberation time.
The first “REVERB” observed by humans was probably heard in a canyon or a cave when we were known as Neanderthal. The repetition of echoes in an enclosed or open space was probably quite frightening and intriguing.
I remember as a kid a place in the mountains called Echo Rock where I would yell something and hear it echo after 1 or 2 seconds. Further down the mountain where the walls were closer together, I would shout and hear a rapid repetition of echoes that I later learned was “reverb.”
The main difference between echo and reverb is the number of repetitions of sound per millisecond. A reverberation is perceived when the reflected sound wave reaches your ear in less than 0.1 second after the original sound wave. Since the original sound wave is still held in memory, there is no time delay between the perception of the reflected sound wave and the original sound wave. The two sound waves tend to combine as one very prolonged sound wave.
For the purpose of this article I will define some terms that I use to describe reverb:
Once a sound event occurs, the first echoes are called “Early Reflections.” These are generally 5 to 20 milliseconds in length.
After that the sound has had a chance to bounce around the room and becomes the “Body” of the reverb. This can last anywhere from 20 milliseconds to infinity.
The last part of the reverb I will call the “Decay or Tail.” This is the last perceptible sounds and can be from .1 to several seconds. The end of the tail occurs when the sound pressure level of the echoes reaches 60dB – close to inaudibility for human ears.
Without getting too technical it should be mentioned that the reverb time of a space has been defined as the time it takes for the initial sound pressure level (SPL) to be reduced by 60dB (for example if the initial SPL is 100 dB, the time it takes to go down to 40 dB would be the RT60 time).
Types of Reverb
The most basic types of reverb fall into five categories.
The first three are naturally occurring phenomena within a physical space and the last two are manmade devices. Though there are many other types that could be mentioned, I will focus on the aforementioned reverb types and their typical uses in today’s music mixes.
The optimum reverberation time for a space in which music is played depends on the type of music that is to be played in the space. Orchestral music is often written with a particular reverb time of the hall to utilize the decay to enhance harmonic structure. Rooms used for speech typically need a shorter reverberation time so that speech can be understood more clearly.
You can hear some academically-oriented examples of reverb in action here.
This term refers to the reverb heard in a concert hall.
Generally the construction of a music hall attempts to produce a reverb that lasts anywhere from 1.2 to 3 seconds or longer. The characteristics include an audible cluster of initial reflections followed by a full body and a decay that ends with a rolloff of high-frequency content.
There are many well-known great sounding Concert Halls throughout the world. Boston Symphony Hall, Vienna’s Musikverein, Walt Disney Concert Hall are a few noted for their accurate and tasteful reverberation characteristics. The most obvious use is for Symphony and Orchestral performance.
If you can’t afford to rent one of these Halls, turn to the digital world.
The Lexicon 224 and 480 were my favorite boxes years ago. Today there are numerous plug-ins that model hall reverbs including Lexicon, Waves and convolution reverbs (convolution attempts to simulate actual physical spaces using impulse responses).