Reflection Points

Above the frequency range of room modes, sound waves begin to behave similarly to rays of light. The most common result of strong wall reflections is a time-smearing, as the listener receives a series of sonic events arriving from the sound source and walls at different times.

The actual frequency at which this behavior begins depends upon room size, and it is typically near 300-600 Hz in an average listening room or studio. Due to this phenomenon, the points upon the wall, floor, and ceiling where reflections are occurring and traveling to the listener can be readily calculated or visually located. Time-smearing is perceived as the listener receives a series of sonic events arriving from (in order of arrival): the sound source, the near wall, the far wall, the front wall, the rear wall, the ceiling...etc.

Excessive reflections can also result in "harshness", as the psychoacoustics of time smearing tend to impart on high-frequency sounds. Additionally, surface reflections can obscure the location of sounds, thus damaging the virtual sound stage. Since the frequency range of this behavior is well into the treble range, typical thin wall panel absorbers will sufficiently abate these reflections. Solutions include diffusion and absorption.