An electro-mechanico-acoustic structure in which magnetic wave energy is converted directly into acoustic energy and partly stored and then converted into audiible acoustic energy in a gradual manner over a period of time.

BACKGROUND OF INVENTION 
Numerous systems and devices have hitherto been proposed for accomplishing 
results which I attain by my invention that have been both complex and 
expensive and in many cases impractical for the uses to which I put my 
invention. The present development provides a reverberation means which is 
simple in construction and can easily be produced by mass production 
methods, and at relatively low cost. 
SUMMARY OF INVENTION 
My invention relates generally to synthesizing reverberant sound effects 
such as are present in large rooms or auditoriums, the boundaries of which 
reflect at least a portion of the sound energy which strikes them either 
directly to indirectly from the original source of the sound. The 
invention has to do with means which may be employed with electrical 
musical instruments, sound amplifying systems, radios, television sets, 
and the like wherein it may be desired to introduce reverberation effects. 
The object of my invention is to provide a small compact reverberation 
device which occupies little space. It is a still further object of the 
present invention to provide a simple, direct method of simulating the 
sound conditions in large rooms having walls which reflect at least a 
portion of the sound energy present in the room. It is a specific object 
of my invention to provide a method and an electro-mechanico-acoustic 
structure in which electric oscillations are converted into mechanical 
vibratory energy and thence into audible acoustic energy, in which the 
magnetic energy is converted into acoustic energy, and partly stored and 
thence converted into audible acoustic energy in a gradual manner. 
Other objects will be set forth hereafter or will be apparent to one 
skilled in the art upon reading these specifications. The constructions 
and arrangements and parts of which I shall describe certain exemplary 
embodiments, reference being had to the accompanying drawing. It will be 
obvious however, that the utility of my invention will be limited neither 
to the embodiments herein described nor to the particular usage which are 
described herein.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is an open mouthed box having members consisting of back 1, top 2, 
sides 3 and 4, and bottoms 5 and 6. An electro-magnet 7 is attached to 
back 1. The embodiment of the invention shown in FIG. 1 is constructed of 
a thin magnetizable steel with a lip 8 formed around the edge of back 1. 
Top 2, sides 3 and 4, and bottoms 5 and 6 may be formed from a strip of 
thin magnetizable steel. The top sides and bottoms are firmly secured to 
lip 8 by a suitable fastening means such as welding or a suitable adhesive 
such as an epoxy resin. Electro-magnet 7 is attached to back 1 with a 
pliable spacer 24 interposed between electro-magnet 7 and back 1 by a 
suitable means such as contact cement. Electro-magnet 7 will not be 
described because such electro-magnet transducers are well known to those 
skilled in the art and two such devices are described in my U.S. Pat. Nos. 
3,449,531 and 4,151,379. When the electro-magnet 7 is electrically 
activated with an oscillatory signal, back 1 acts as an audio transducer 
armature and vibrates, emitting sound without additional amplification. 
The vibrations are transferred to top 2, sides 3 and 4 and bottoms 5 and 
6. The foward edges of top 2, sides 3 and 4 and bottoms 5 and 6 are 
substantially undamped and are free to continue to vibrate when activated 
by vibrations, thereby storing the vibratory energy and releasing it over 
a period of time as audible sound. The members 1,2,3,4,5, and 6 are sound 
radiating elements when vibratorily activated and are tuned to different 
resonant frequencies. The different tuned resonant frequencies of the 
sound radiating diaphragm causes this invention to store the vibrations 
over a broad frequency range to be gradually released over a period of 
time. 
This invention may be constructed from 24 gauge cold rolled steel and may 
be approximately 10 inches long, 6 inches deep and 6 inches high. This 
size produces a very pleasant echo effect but the reverberation delay time 
may be increased by enlarging the structure and by varying the thickness 
of the material. Bottoms 5 and 6 may be solid or be separated by gap 9. 
The advantage of this separation is that the bottoms 5 and 6 may be tuned 
to different resonant frequencies and have a longer undamped edge that 
allows them to have a longer reverberation time. Gap 9 may be varied in 
width. Gaps may also be placed at other desired locations on the other 
sound radiating members 1,2,3,4 to obtain different reverberation time 
periods. Electro-magnet 7 is magnetically coupled to back 1. The 
electro-magnet 7 directly transfers its magnetic wave energy to back 1, 
causing the sound structure shown in FIG. 1 to become a magnetically 
activated armature and the primary sound reproducing vibratory element of 
the audio transducer 7. The vibrations impressed on back 1 are transferred 
to top 2, sides 3 and 4 and bottoms 5 and 6, which sustain the vibration 
and gradually release the vibrations as audible sound. Member 10 is an 
optical screen used to conceal electro-magnet 7 from view and may be 
constructed from any suitable material. It may be fastened to lips 8 or 
near the rearward edges so as not to attach to any portion of the primary 
sound radiating elements which would substantially dampen the vibratory 
storing ability of the sound radiating elements. An audio transducer 25 as 
shown in FIG. 3 may be attached to back 1 rather than the electro-magnet 
alone. This invention may be constructed from materials that are metal in 
whole or in part. Cushion pads 19 may be fastened to the bottom of the 
invention to cushion it when placed on another object such as a table. 
FIG. 3 shows the invention constructed of thin wood such as plywood. To 
obtain the reverberatory effect given by metal, the structure constructed 
from wood will be required to be much larger. Back 1 may be constructed of 
metal or wood or other material and top 12, sides 13, and bottom 14 from 
metal or wood or in combination with each other. An audio transducer 25 
may be attached to back 11 by any suitable means or as shown by screwing 
it into wood block 15 with screw 21 attached to magnetizable plate 20. 
Wood block 15 is attached to back 11 with glue or any other suitable 
means. Audio transducers are well known to those skilled in the art and 
are described in my U.S. Pat. Nos. 3,449,531 and 4,151,379. FIG. 4 shows a 
different method of connecting the sound radiating elements together. 
Rivets 22 may be used or screws and nuts. All connections must be tight or 
a rattle will be audible when the invention is in operation. 
Electro-magnet 7 or audio transducer 25 may be attached to any sound 
radiating member of the sound structure but best results will be usually 
obtained by attaching the transducer to the back 1 or 11. FIG. 5 shows the 
preferred method of use of the invention together with a primary sound 
radiating source. The purpose of the invention is to add reverberation to 
the primary sound. The invention is not intended to be the primary sound 
source but only to supply the reverberation components of the sound to be 
blended with the primary sound source 17 such as a loudspeaker as shown in 
FIG. 5. The invention and the primary sound geenrator 17 will usually be 
electrically connected in parallel with electrical signal balancing means 
18 interposed in the electrical circuit such as a fixed or variable 
resistor or other balancing means. Other suitable electrical connecting 
means may be used. This blending will approximately duplicate the actual 
reverberation produced by an auditorium because the sound radiating 
elements of the invention are unbaffled. The unbaffled sound radiators are 
tuned to different resonant frequencies and different vibratory energy 
will be dominant on the different sound radiating members. The unbaffled 
sound radiating diaphragms resultin cancellations and reinforcements of 
the primary audible sound signal and also the synthesized reverberation 
audible sound signals as would result in an auditorium when the generated 
sounds are reflected in the auditorium and blended together in the 
listener's ear. 
A piezo electric element or microphone 16 may be attached to the sound 
structure to convert the vibratory energy into an electrical signal 
through leads D--D for use to supply other electrical amplifying means. 
Leads B--B to electro-magnet 7 or audio transducer 25 are connected to any 
device that will supply a suitable electrical signal to leads B--B. 
It will be understood that details shown and described of the construction 
may be altered or omitted without departing from the spirit of this 
disclosure as defined by the following claims: