Free field
In acoustics, free field is a sound situation in which no reflections occur.
In the free field, the entire sound that a listener (or a microphone) picks up is determined by the direct sound of a sound source . The free field is also referred to as the direct field .
Free field conditions can only be found in nature if z. B. reflections on the ground play no role, z. B. with fresh snow in a field or more or less sound absorbing soils (leaves, dry sand, etc.)
Free field conditions can be created artificially in anechoic rooms . Examinations under free-field conditions play an important role, particularly in acoustic measurement technology and in listening tests , since the results are then only influenced by the sound of the sound source and not by reflections from the room.
In the case of voice and sound recordings, too, one often strives for freedom from reflection, as under free-field conditions, even if only in order to be able to add a desired spatial impression via appropriate post-processing that is not falsified by the recording space.