The history of reverb and echo in audio production dates back to before mankind existed. Even before human beings, creatures and nature generated sounds that resulted in natural reverb and echo. Today, thanks to advancements in technology, there are numerous methods available to create reverb and echo. Engineers can utilize anything from large metal sheets to plug-ins in digital audio workstation (DAW) software on a computer to incorporate and take advantage of reverb and echo effects in recorded audio tracks.
But before diving into modern methods of recording reverb and echo, let’s first understand the origins and definitions of these phenomena. Reverberation, commonly known as reverb, is the reflection of sound waves off surfaces surrounding the sound source, before reaching the listener’s ear. Reverb is essentially a combination of multiple fast echoes that blend together so quickly that the human ear cannot distinguish them as separate delayed repetitions. Only when these repetitions are heard as distinct duplicates does it qualify as echo.
In the early days of radio, radio signals were transmitted through a distant line and then brought back. A simple way to experience reverb is by entering an empty room and clapping. Immediately after clapping, the sound of the clap would decay, creating the effect of reverb. During the early days of recording, capturing reverb was as easy as moving the microphone away from the sound source to achieve the desired amount of reverb. Another technique called tape echo involved recording sound with one head and playing it back using a different head.
The space between the two determined the delay, and some units had multiple heads for simultaneous delays. Engineers would also add feedback to create repeated echoes. In 1948, Les Paul modified the tape machine by adding another recording head. Another method of producing echo was using oil cans filled with oil (known as oil can echo). Wallace Clement Sabine pioneered architectural acoustics, while Bill Putnam Sr. was the first to employ artificial reverb in his bathroom-turned-reverb chamber.
A reverb chamber, also known as an echo/reverb chamber, is a hollow arena designed to produce echoing sounds. This is achieved by constructing a room with non-parallel surfaces and applying shellac to all the surfaces to ensure they are acoustically reflective. The chamber is equipped with a speaker and microphones which capture the reflection of the speaker’s output. This method gained popularity in the 60’s. However, a new technology called Spring reverb emerged as an alternative. In the early days of recording Elvis, Sam Phillips of Sun Records utilized tape echo. Spring reverb, on the other hand, is a form of electromechanical reverb device.
The creation of a reverb effect occurs through the induction of sound vibrations at one end of a coiled wire, also known as spring reverb. To minimize its space, the wire is shaped into a spring. Vibrations are then captured by another transducer located at the opposite end. As the waves continuously travel back and forth within the spring, a reverb effect is generated. Spring reverbs are known for their harsh and trebly sound, and their susceptibility to external shocks. However, they are cost-effective to construct and introduced a novel approach to achieving reverb.
In 1957, EMT (Elektromesstecknik), a German company, revolutionized the reverb game by introducing the first plate reverb system called EMT 140 Reverberation Unit. This advanced technology used an electromechanical transducer to induce vibrations in a large sheet metal plate. The vibrations were captured by a pickup and bounced across the plate, resulting in an audio signal output. Initially, the system had one pickup for mono output, but later models incorporated two pickups for stereo use.
A framed acoustic slate pad can be used to adjust the reverb time. The proximity of the pad to the plate affects the length of the reverb time, but the pad does not make direct contact with the plate. Certain high-cost models even come with a remote control for convenient access. Some electronic delay methods utilized bucket brigade chips, which would store information for a set duration before passing it on to the next chip. In contemporary times, reverb is commonly achieved through plug-ins or programs on a Digital Audio Workstation (DAW) or an external digital unit, known as digital reverb.
Digital reverb utilizes diverse signal processing algorithms to generate the reverb effect, creating multiple feedback delay circuits that result in an extensive decay of echoes. Both digital reverb units or programs possess numerous adjustable parameters capable of modifying different aspects of the reverb. Another type of digital reverb is convolution reverb, which digitally emulates the reverberation of either a physical or virtual environment. Many individuals favor the natural reverb found in a room over any artificially processed reverb, prompting some studios to have dedicated reverberation rooms for recording music in its authentic state instead of applying processing techniques.
Many engineers often mix different microphones together, while numerous artists enjoy incorporating echoes or “delay” into their music. These noticeable duplicates of the sound source can create a highly desired and attention-grabbing effect, but they can also be risky if not utilized correctly. One popular form of delay is Echoplex, which generates multiple echoes that align approximately with the music’s rhythm. Another kind of delay called Doubling echo is produced by adding a short-range delay to a recorded sound. This specific type of delay typically ranges from thirty to fifty milliseconds and is commonly employed.
Longer delay times would result in Slapback echo. Slapback echo utilizes a lengthier delay time (seventy-five to 250 milliseconds) and minimal or no feedback. This effect was frequently employed in the vocals of 1950s rock-n-roll recordings. It is also occasionally applied to instruments, particularly drums and percussion. Analog and digital delay machines are capable of easily producing this effect. Flanging and chorus are sound effects that rely on delay. In flanging and chorus, the delay time is very short and typically undergoes modulation. Reverb has been integrated to be compatible with various musical instruments.
Guitar amplifiers have reverb knobs to enhance the guitar’s size and create a sense of being in a large hall. Additionally, guitar players can use digital delay and reverb pedals to produce impressive loops and ambient sounds. Reverb adds authenticity to the sound, making it feel almost three-dimensional, as if it was played right in front of the listener. Musicians have been utilizing various forms of reverberation and echoes in their music since the inception of recorded music, continuing to do so today. Undeniably, reverberation stands as one of the finest effects for music and any other application of recorded sound.
