Background and Field of the Invention

This invention relates to sound reproduction systems and more particularly relates to a novel and improved system of the type described for enhancing stereophonic perception of sound upon the ear of the listener.

Numerous systems have been devised for improving the quality of sound reproduced from an audio source. Typical of such systems are the stereophonic and quadraphonic systems in which two or more speakers are spaced at intervals about a room and the sound produced is radiated from different angles or locations toward the listener. In the past, considerable attention has been given to the quality of recording the sound as well as the quality of equipment employed to refine the sound when reproduced for the listening pleasure of an audience.

One typical approach is that disclosed in U.S. Letters Patent No. 4,612,663 to K.A. Holbrook et al in which four speakers are arranged in a generally T-shaped configuration with left, front and right speakers in a vertical plane and a rear speaker behind that plane. The system is designed to generate both in-phase and out-of-phase signals (L-R or R-L) to the front and back speakers in order to achieve higher quality or realism in the sound. Another U.S. Letters Patent, No. 3,757,047 to R. Ito et al, utilizes signals which are generated out-of-phase with respect to one another in a loudspeaker arrangement. U.S. Patent No. 3,697,692 to D. Hafler similarly employs out-of-phase signals with various different loudspeaker arrangements to enhance the realism of sound. U.S. Letters Patent No. 3,745,254 to K Ohta et al has an arrangement of four loudspeakers operated from a two-channel source in which the four speakers are equidistantly spaced apart and receive different signals with a phase shift introduced between the signals but requires special equipment to generate the out-of-phase signals.

In accordance with the present invention, it has been found that not only may the manner of generating a phase relationship between signals be greatly improved but also the spacing and location between pairs of standard stereophonic speakers and auxiliary speakers to greatly enhance the dimensional reconstruction of the sound and its effect on the listening audience.

Summary of the Invention

Accordingly, an object of the present invention is to provide for a novel and improved audio system for enhancing the production of sound and realism of the sound as produced in a stereophonic system.

It is another object of the present invention to provide for a novel and improved method and means for converting audio signals into a combination of direct and indirect or reflected sounds which will converge from different directions upon the ear of the listener in such a way as to create greater realism and purity of sound.

It is a further object of the present invention to provide for a novel and improved stereophonic system for developing multi-dimensional sound from a combination of in-phase and out-of-phase signals converging upon the ear of the listener from different directions.

It is an additional object of the present invention to provide for a stereophonic system in which front-to-­rear sonic difference information is derived from conventional left and right stereo signals through a combination of unique speaker placement, speaker direction and left and right stereo signal phase differences; and wherein a high quality stereophonic system has been devised through the utilization of low-­cost speakers in combination with conventional full-­range speakers.

In accordance with the present invention, there has been devised a novel and improved multi-channel stereophonic system for producing left (L) and right (R) stereo signals from an audio source wherein first and second speakers are arranged in horizontally spaced relation to one another each for producing and directing one of the left (L) and right (R) signals in a common horizontal direction, and third and fourth auxiliary speakers are positioned in front of and above the first and second speakers. Means are provided for transmit­ting one of the left (L) and right (R) signals in-phase both to one of the first and second speakers and to one of the third and fourth speakers, and further means are provided for transmitting the other of the left (L) and right (R) signals in-phase to the other of said first and second speakers and out-of-phase to the other of the third and fourth speakers. Accordingly, all of the signals are transmitted in-phase except for one signal which is transmitted out-of-phase to one of the third and fourth speakers. Preferably, one of the third and fourth speakers directs the sound produced by the in-­phase signal at right angles to the sound produced by the out-of-phase signal delivered by the other of said third and fourth speakers, and means including a first sound-reflective surface, such as a sidewall of a room, reflects the sound from the in-phase signal and a second sound-reflective surface, such as a ceiling at right angles to the first sound-reflective surface, reflects the sound from the out-of-phase signals whereby four different signals are produced by the four speakers and converge upon the ear of the listener from different locations and at selectively spaced time intervals to enhance the realism of the sound impressed upon the listener. In accordance with the instant invention, fifth and sixth auxiliary speakers are provided which face a rear reflective surface. One of the fifth and sixth speakers is connected out of phase with the audio source.

Other objects, advantages and features of the present invention will become more readily appreciated and understood when taken together with the following detailed description in conjunction with the accompanying drawings, in which:

Brief Description of the Drawings

• Figure 1 is a circuit diagram illustrating a first embodiment of a stereophonic sound system in accordance with the present invention;
• Figure 2 is a general schematic plan view of the stereo system of Figure 1 positioned in a room of a selected size and in predetermined relation to a listener(s) stationed in that room;
• Figure 3 is a side view in elevation of the stereophonic system illustrated in Figure 2;
• Figure 4 is a circuit diagram illustrating a second embodiment of a stereophonic sound system in accordance with the instant invention;
• Figure 5 is a general schematic plan view of the stereo system of Figure 4;
• Figure 6 is a side view of the stereophonic system of Figure 4; and
• Figure 7 is a perspective view of a speaker suspended from a room ceiling in the manner of a suspended lamp for directing audio signals vertically.

Detailed Description of the Preferred Embodiment

Referring in more detail to Figures 1-3 of the drawings, there is illustrated in Figures 1 and 2 a first embodiment of a sound reproduction system 10 in which an audio source, not shown, of a standard stereophonic system has a stereophonic amplifier 12 provided with left channel positive and negative output terminals 14,15 and right channel positive and negative output terminals 16,17, respectively. Each of the left and right terminals as described are connected via a routing circuit or network 20 to left and right main speakers 22,23 and to left and right auxiliary speakers 24,25 in a manner to be described.

As shown, positive terminal 14 is connected via line 26 to positive input terminal 32 of the left main speaker 22 and via line 27 to positive terminal 35 of the right auxiliary speaker 25. Negative terminal 15 is connected via lines 28 and 29, shown dotted, to negative terminal 32′ of the left main speaker 22 and negative terminal 35′ of the right auxiliary speaker 25.

The right positive terminal 16 from the amplifier 12 is connected via line 30 to negative terminal 24′ of left auxiliary speaker 24 and via line 31 to positive terminal 33 of the right main speaker. The negative terminal 17 is connected via line 37 to positive input terminal 34 of the left auxiliary speaker 24 and via line 38, shown dotted, to negative terminal 33′ of the right main speaker 23. Thus, in the relationship described, a conventional stereo system having two speakers is combined with two auxiliary speakers in which the signal or sound information from one channel and connected to one of the main speakers in-phase is connected out-of-phase to one of the auxiliary speakers, and the information from the other channel is connected in-phase both to the other of the main speakers and the other of the auxiliary speakers. More particularly, there is a left main speaker 22 and left auxiliary speaker 24 in combination with a right main speaker 23 and a right auxiliary speaker 25, the left channel information being connected in-phase to the left main speaker and out-of-phase or, in other words, the polarity is reversed, to the right auxiliary speaker; and the right channel information is connected in-phase both to the right main speaker and to the left auxiliary speaker. Although the system is illustrated and described with the right channel information connected out-of-phase to the left auxiliary speaker and the left channel information connected in-­phase to the right auxiliary speaker 25, the connection may be reversed such that the left channel information is connected out-of-phase to the right auxiliary speaker 25 and the right channel information is connected in-phase to left auxiliary speaker 21.

In Figures 1 and 2, the speaker system is illustrated in an enclosed area, such as, for example, the room R which is made up of a floor surface represented at 40, ceiling 41, front wall 42, rear wall 43 and opposite sidewalls 44 and 45. A listener as represented at L is generally representative of one or more persons situated relatively near the front wall 42 and away from the rear wall 43, although the particular location of the listener or audience in the room is not critical to the invention. In turn, the stereophonic system is arranged such that the left and right main speakers 22 and 23, respectively, are situated on opposite sides of the room relatively near the left and right walls 44 and 45, respectively, and with the speakers facing or directed toward the front wall 42.

In order to enhance the quality of sound from the speaker system, the auxiliary speakers 24 and 25 are elevated with respect to the main speakers 22 and 23 and are positioned or directed such that the sound from each is reflected art different angles and caused to converge upon the ears of the listener or audience from different locations and out-of-phase with respect to one another. To this end, each of the auxiliary speakers 24 and 25 is mounted at the free end of a horizontal extension arm 48 of an upright standard or post 49 with the arm 48 extending forwardly and spaced above the main speaker for a distance above the floor such that the speakers 24 and 25 are located proximate to the ceiling 41 but spaced inwardly and forwardly of the main speakers 22 and 23. The left auxiliary speaker 24 is positioned such that the speaker cone 50 of the speaker is directed upwardly toward the ceiling 41 so that the sound generated by the speaker 24 is reflected off of the ceiling surface. In turn, the auxiliary speaker 25 has its speaker cone 52 directed horizontally toward the sidewall 45 so that the in-phase signal generated by the speaker is reflected off of the sidewall 45, or at right angles to the out-of-phase signal emanating from the speaker 24.

In the relationship described, the front/rear spacing of the front auxiliary speakers 24 and 25 to the rear main speakers 22 and 23 in combination with the out-of-phase, reflected signals produced by the auxiliary speakers 24 and 25 converging upon the ear of the listener at different angles and phase and time intervals has been found to achieve or produce high quality, pure and realistic sounds. In this relation, the direction of the speaker cones may be reversed, if desired, without detracting from the realism of the sound produced.

Referring now to the second embodiment of the invention illustrated in Figures 4, 5 and 6, a pair of rear speakers 60 and 61 (fifth and sixth speakers, respectively) are positioned adjacent the rear wall 42 of the room R in spaced relation thereto. The speakers 60 and 61 face the rear wall while facing away from the listener L and are positioned behind and above the listener so that their audio signals are reflected off the wall 42 before being heard by the listener.

As is shown in Figure 4, the left rear speaker 61 is wired in-phase with the left front speaker 22 by having positive terminal 62 connected via line 63 to the positive terminal 14 of the stereo amplifier output 12 and having negative terminal 64 connected via line 65 to the negative terminal 15 of the amplifier. Note that the left rear speaker 61 is out-of-phase with the upwardly facing speaker 24 which has the polarity of its inputs reversed. The right rear speaker 60 is wired out-of-phase wit both the right front speaker 23 and the left front speaker 22 by connecting the positive terminal 67 of the right rear speaker 60 to the negative terminal 17 of the stereo amplifier output 12 via line 68 and the negative terminal 69 of the right rear speaker 60 to the positive terminal 16 of the stereo amplifier output via line 70. In the embodiment of Figures 4-7, the right rear speaker is also wired out-­of-phase with the in-phase wired laterally facing front speaker 25.

Figure 7 illustrates an embodiment of the upwardly facing speaker 24 shown in Figures 1-6 wherein the speaker mount 24′ having a speaker or an array of speakers 50′-50˝ is suspended by a chain 71 from the ceiling 41 of the room R. The lines 30′ and 37′ connect terminals 34˝ and 34′′′ of the speaker 24′ out-of-phase to the stereo amplifier output 12 in the same manner as the lines 30 and 37 connect the speaker 24 of Figures 1 and 4. The lines 30′ and 37′ are woven in the chain 71 in the same manner as the power cord is woven in a light chain. As with a light chain, the chain 71 hangs from a ceiling hook 72. The chain suspension arrangement of Figure 7 is an alternative to the boom suspension arrangement of Figures 2, 3, 5 and 6 for the speaker 24.

It is, of course, possible to suspend the sideways facing speaker 25 in the manner shown in Figure 7 so that the loud speaker 72 (dotted lines in Figure 7) faces the side wall 45 of the room R. In order to do this, the links of the chain 71 must be fused on the speaker or otherwise restrained in order to keep the speaker properly oriented.

For the purpose of illustration but not limitation, for a room on the order of 10 feet x 12 feet having a ceiling on the order of 8 feet hight, most desirably the main speakers 22 and 23 are spaced approximately 8 feet apart, and the auxiliary speakers 24 and 25 are spaced approximately 5 feet in front of the main speakers 22 and 23 and on the order of 6 feet apart and at an elevation of approximately 6 feet to 7 feet. The fifth and sixth speakers 60 and 61, respectively are spaced perhaps 1 foot to 4 feet from the rear wall 42 and laterally positioned just out board of speakers 24 and 25, approximately in alignment with speakers 22 and 23. Depending upon room size, sound-reflective surfaces other than the ceiling 41 and walls 42, such as the walls 44 and 45, may be employed at selected spaced distances from the outlet ends of the speaker cones to produce the desired reflection of the signal or signals. Essentially, the different signals produced are the result of direct in-phase signals produced by the forwardly facing, main speakers, and the reflected in- and out-of-phase signals of the upwardly and sidewardly directed auxiliary speakers located above and forwardly of the main speakers and the reflected in- and out-of-­phase signals of the fifth and sixth rear speakers which reflect sound off the rear wall 42. This arrangement results in greater musical definition, more solid instrument location and a definite recreation of room acoustics.

It is to be understood that various modifications and changes may be made in the specific location, facing and spacing of the speaker components making up the system of the present invention.