Diffuse field equalization
The diffuse-field equalization is an acoustic linearization of the frequency response for a pressure microphone , located in the diffuse sound field , ie in the space sound field , is R. In such a diffuse sound field of the sound from all directions equally applies to the diaphragm of the microphone . In contrast to this, there is the free field , also called direct sound field D, in which the sound only hits the membrane from the frontal directions of sound incidence .
In the case of a diffuse-field equalized microphone, the usual treble increase at 10 to 12 kHz is present, especially for the direction of sound incidence from the front. In the diffuse field, ie when there are many reflections everywhere , there is therefore a “flat” frequency response. In the free field, the diffuse-field equalized microphone shows an overall increase in height when sound is incident from the frontal directions.
Similarly, there are also microphones that are equalized for the free field . In the free field, the frequency response is linear in the treble, while in the diffuse field there is an audible treble reduction.
Free-field and diffuse-field equalization are also available in artificial heads and headphones . Headphones do not need a linear frequency response because they sit directly on the ear. A different outer ear transmission function applies here than for speakers placed on the front . To ensure that headphones have the same perceived frequency response as stereo speakers placed on the front, corrections must be made to the frequency response that are essentially "mirror images" of those of a diffuse-field equalized microphone, i.e. H. the level of the upper frequency ranges must be lowered.
literature
- Thomas Görne: Sound engineering. 1st edition, Carl Hanser Verlag, Leipzig, 2006, ISBN 3-446-40198-9
- Thomas Görne: Microphones in theory and practice. 8th edition, Elektor-Verlag, Aachen, 2007, ISBN 978-3-89576-189-8