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Publication numberUS1786279 A
Publication typeGrant
Publication dateDec 23, 1930
Filing dateMar 31, 1927
Priority dateMar 31, 1927
Publication numberUS 1786279 A, US 1786279A, US-A-1786279, US1786279 A, US1786279A
InventorsIrving Wolff
Original AssigneeRca Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
US 1786279 A
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Description  (OCR text may contain errors)

ADec. 23, 1930.- l. WOLFF I 1,786,279


The invention concerns acoustic devices of the type generally known as loud speakers and has for its principal object to provide a sound reflector in connection with such a device A more specific object of the invention is to provide a sound reflector in combination with a loud speaker for reflecting the sound waves therefrom in order to modify the direction of the sound or to decrease or amplify certain frequency ranges.

In the construction of loud speakers it is often necessary for structural purposes or other reasons to so locate the sound emitting element that Athe direction of maximum sound intensity or of more nearly perfect transmission is not in the direction of the audience. It may benecessary for example to locate the vibratile element so that the sound waves emitted from it will be directed ina vertical direction whereas the listener usually will be located in a horizontal direc tion from the loud speaker. It is known that the low frequency waves will extend with a substantially equal intensity in all directions, that is there is a tendency for the low frequency waves to change their direction of propagation readily or in other words, to spread out in all directions. The high frequency sound waves, however, have a tendency to persist only in the direction in which they start. The high frequency waves, in other words, instead of spreading out in all directions have more or less the form of a beam which in the case of a loud speaker extends directly away from it. It is obvious, therefore, that if the vibratile element were placed horizontally that the low frequency tones would probably be of sufficient intensity in all directions but the high frequency tones would extend directly upward and would have little effect in the horizontalV di rection in the loud speaker. The resulting sound7 therefore, would have its high frequency components weakened so that the speech or music being produced would not correspond at all to that originally causing the vibration of the vibratile element. I propose to overcome this, defect by providing a sound reflector in proximity to the vbratile 1927. Serial No. 179,744.

element so that the high frequency waves will be directed from their original path into the direction which it is desirable that the sound from the loud speaker be heard.

The invention further contemplates the use of a reflector in connection with a loud speaker to amplify certain frequency ranges of the loud speaker or to decrease certain frequency ranges. It is well known that the usual sound emitting device has several frequency ranges that are unduly accentuated with respect to the others resulting in distortion of the original sound. On the other hand the element may respond very poorly to certain frequencies within its operating range resulting in a decided dip in its respense curve. By the use of a reflector of suitable construction and material it is possible to strengthen or decrease as desired the intensity of the sound of particular frequency ranges. This may be done by so` placing the vibratile element that it vibrates in a direction different from that in which it is desired'that the sound be heard and then providing a reflector which will reflect the sound waves into the desired direction. By suitably choosing the reflector it can be made to reflect some frequencies and absorb others from which it will result that the sound after it leaves the reflector will have certain frequencies of substantially the same intensity as they left the vibratile element and others will be decreased in intensity. In this manner a more uniform response over the entire frequency range of the vibratile element may be obtained.

A more particular use of the reflector occurs where a vibratile element is used hat7` ing a rise in its characteristic curve within the low frequency range. It is well known that the diaphragm or other vibratile elementemits sound waves from its two sides simultaneously and these waves are directly out of phase with each other. This effect is of no importance with respect to the high frequencies as they tend to persist in their original direction and the wave length is too short to give interference but the low frequency waves tend to spread out in all directions and if no means were taken to prevent it those i to actuate said diaphragm, a casing enclosing said means and said diaphragm, said casing having an opening substantially the same shape as said diaphragm, and a reflector mounted adjacent to said opening and angularlv disposed With respect to the plane of said diaphragm.

6. In combination, a loudspeaker device having a vibratile element, and an ellipsoidally shaped reflector mounted adjacent to said element.

7. The combination of an acoustic device and an elliptical reflector associated therewith.

8. The combination of an acoustic device and a reflector therefor, said reflector having a surface at least a part of which is an ellipsoid of revolution.

9. The combination of means forming a refleeting surface having the form of an ellipsoirl of revolution and an acoustic device positioned substantially at the focal point of said ellipsoid.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2643727 *May 20, 1950Jun 30, 1953Elipson S ASound transmitting device with an ellipsoidal reflector
US2732907 *Jun 17, 1952Jan 31, 1956 Sound transducers
US2816620 *Aug 25, 1955Dec 17, 1957Mosack Anthony JAudio modulating and control device
US2993557 *Sep 22, 1958Jul 25, 1961Mcdonald Clifford COmnidirectional stereo system
US4001893 *Oct 4, 1974Jan 4, 1977Matsushita Electric Industrial Co., Ltd.Portable tape-recorder
US4421200 *Dec 16, 1981Dec 20, 1983Ferralli Michael WElliptically shaped transducer enclosure
US4593784 *May 3, 1984Jun 10, 1986C. Harold Weston, Jr.Loudspeaker enclosure
US4625829 *Mar 26, 1984Dec 2, 1986Sirois Ronald ASpeaker grill
US4836329 *Jul 21, 1987Jun 6, 1989Hughes Aircraft CompanyLoudspeaker system with wide dispersion baffle
US4907671 *Apr 8, 1988Mar 13, 1990Unique Musical Products, Inc.Wide dispersion reflector
US5225639 *Jun 3, 1991Jul 6, 1993Pioneer Electronic CorporationLoudspeaker
US5784468 *Oct 7, 1996Jul 21, 1998Srs Labs, Inc.Spatial enhancement speaker systems and methods for spatially enhanced sound reproduction
US6334505 *Aug 16, 1993Jan 1, 2002Ming-Chiang LiOptimum edges for speakers and musical instruments
US8259965 *Jul 26, 2010Sep 4, 2012Hon Hai Precision Industry Co., Ltd.Loudspeaker device with sound enhancing structure
DE970013C *Aug 29, 1950Aug 14, 1958Siemens AgEinrichtung fuer Lautsprecher
DE1288147B *Jul 5, 1962Jan 30, 1969Greenfield Daniel KLautsprecheranordnung fuer eine Stereophonieanlage
U.S. Classification181/155
International ClassificationH04R1/34, H04R1/32
Cooperative ClassificationH04R1/345
European ClassificationH04R1/34C