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US 4,357,499 AGranted
Acoustic test box
OwnerPer V. Bruelinventor
Life of this patent
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OwnerPer V. Bruelinventor
Estimating the term…
In prior art acoustic test boxes, which can function as small anechoic chambers, it has been difficult to attain a frequency-independent pressure field at the test point without simultaneously increasing the frequency dependency of the velocity field, whereby tests of objects which are partly pressure sensitive and partly velocity sensitive are vitiated by errors. An elongated acoustic test box provided exclusively with curved surfaces and with space for an effective sound absorbent behind the test object overcomes this problem and at the same time provides improved acoustic insulation against low-frequency ambient noise. In a particularly appropriate embodiment the box (1) is shaped like an egg supported at its narrow end on a support (2) and divided about two-thirds of the way up into a bottom part (4) and a cover (5), the latter containing a sound source (10).
An acoustic test box (1) comprising a rigid hollow top curved section (5) and a mating rigid hollow curved bottom section (4) and means (6) for connecting said two sections together to form a rigid hollow container, the inner surface of said container sections being lined with sound-absorbing materials (8,9) to enclose an anechoic test chamber accommodating a sound source (10), a test object (12) and a test microphone, all the surfaces of said container, the inner ones as well as the outer ones, consisting entirely of curved surfaces to enable the chamber to display an essentially constant velocity field and an essentially constant pressure field throughout the frequency range over which the frequency response is to be tested and to thereby secure substantially the same frequency response from said test object whether it be pressure sensitive or velocity sensitive.
Dependencies are inferred from the claim text.