According to standard definitions, early reflections are sounds that arrive at the listener after being reflected maybe once or twice from parts of listening space, such as walls, ceilings and floor. They arrive later than the direct sound, often in a range from 5 to 100 milliseconds, but can arrive before the onset of full reverberation. The early reflections give your brain the information about the size of a room, and for the sense of distance of sounds in a room. They have an important role in determining the general character and sound of the room.
There are those who disagree with the assumption that reverb is based on two discrete components “Early reflections” and “Reverberant field”. The “Early reflections” are often recreated by using a bunch of taps off a delay line, supposedly representing the sound reflected for the first time from all the walls and ceiling. The “Reverberent field” is a diffuse scrambling of the early reflections, with some kind of feedback to keep it going.
Both Lexicon and Quantec companies assert that early reflections are a purely academic concept, if not a myth altogether – at least in terms of designing their signal processors, which stand by far, as some of the best reverb units in the world.
Quantec’s argument against early reflections is simple and philosophical: A room is just one signal processor of sound. It doesn’t have the intelligence to separate out the two concepts or even to care about whether a sound is direct or reflected. It just bounces and diffuses all sound, no matter what its source.
Lexicon’s argument against early reflections is a little more descriptive: They also argue that a room just reflects and diffuses sound, irrespective of source, but point out as well, that you could be hearing second or third generation reflections from the areas around you, before you even get the first reflection off the back wall. Reverb, according to Lexicon, is an extremely complex reflection and diffusion pattern that builds up to a dense thickness from the moment you hear the original dry sound onwards. That’s why the controls on a Lexicon are quite different to other reverb units, including parameters like “spread” and “shape” to control how the reverb thickens and builds up before decaying.
Nevertheless many artificial reverb units do treat the early reflections separately, and have a separate group of parameters to adjust accordingly. And regardless of what terminology we want to apply, or whether we wish to address specific parameters in signal processing equipment it is known that there can be some discrete delays or echos that may reach a listener in a space that could potentially be characterized as separate from the overall reverberation. That’s what people refer to when speaking of early reflections.