Aneic

Aneic, also spelled anæic, is an adjective used in acoustics to denote the absence of echoes or reflections. It is commonly applied to environments, surfaces, or measurements that do not reflect significant sound. The term derives from Greek roots meaning without echo and is closely related to the word anechoic.

Aneic conditions are most often realized in anechoic chambers and on acoustically absorptive surfaces. Such spaces are lined with sound-absorbing wedges or porous foams and are designed to minimize standing waves and reverberations, producing a reverberation time effectively zero for airborne sound. The walls, floor, and ceiling are typically highly absorptive over a broad frequency range; some chambers employ non-parallel surfaces to reduce flutter echoes.

Aneic conditions are used in a variety of applications, including measurement of loudspeakers, microphones, and hearing aids, product acoustics testing, and psychoacoustic experiments. They provide a controlled, reflection-free background against which sound power, directivity, or spectral content can be isolated. The environment can produce unusual perceptual effects for listeners, since normal spatial cues from room reverberation are removed.

The opposite condition is reverberant or echoic, where sound reflections are significant and contribute to the overall acoustic field.