US3777071A

US3777071A - Sound sequence interval changing structure

Info

Publication number: US3777071A
Application number: US00238068A
Authority: US
Inventors: J Oppenheimer
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-03-27
Filing date: 1972-03-27
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04

Abstract

A system is disclosed for reproducing and recording a sound sequence in a time interval that is different than the interval of the original performance sequence. A fragment of the sound energy provided by an original performance or delivery is isolated into a substantially pure form (including essentially no echoes) and is converted into an electrical audio signal. The audio signal is then expanded or compressed to the desired time interval and subsequently recorded, as on a magnetic tape medium. As disclosed, the isolation operation involves the use of an anechoic chamber into which the sounds of the original delivery are introduced for subsequent conversion into an electrical signal.

Description

United States Patent [1 1 Oppenheimer Dec.4,1973

[ SOUND SEQUENCE INTERVAL CHANGING STRUCTURE [76] Inventor: Jess Oppenheimer, 549 Moreno St.,

Los Angeles, Calif. 90049 [22] Filed: Mar. 27, 1972 [21] Appl. No.: 238,068 a [52] US. Cl... 179/l00.2 K, 179/1 P, l79/100.2 B, l79/15.55 T, l79/100.2 RE

[51] Int. Cl. Gllb 27/00 [58] Field of Search 179/1 P, 100.2 K, 179/100.2 B, 15.55 T, 100.2 RE

[56] References Cited UNITED STATES PATENTS Mullin 179/ 100.2 K Bennett 179/l00.2 K

Primary Examiner-Terrell W. Fears Att0mey-Billy A. Robbins et al.

[5 7] ABSTRACT A system is disclosed for reproducing and recording a sound sequence in a time interval that is different than the interval of the original performance sequence. A fragment of the sound energy provided by an original performance or delivery is isolated into a substantially pure form (including essentially no echoes) and is converted into an electrical audio signal. The audio signal is then expanded or compressed to the desired time interval and subsequently recorded, as on a magnetic tape medium. As disclosed, the isolation operation involves the use of an anechoic chamber into which the sounds of the original delivery are introduced for subsequent conversion into an electrical signal.

11 Claims, 3 Drawing Figures Manetkc -7Ez,ae

Re cord mg EXPAND Wei/ SPEED CONTROL.

SOUND SEQUENCE INTERVAL CHANGING STRUCTURE BACKGROUND AND SUMMARY OF THE INVENTION The desirability of recording a sound sequence in an interval that differs from the interval of the original delivery (without changing the pitch of individual sounds) has been previouslyrecognized. For example, expansion or compression of the interval of an originating performance may be desirable to accommodate the sound sequence to a particular time slot, as in radio broadcasting or commercial recording. Time variations in recorded material may also be desirable in relation to the-use of the recorded material. For example, in analyzing or studying recorded material it may be desirable to expand the delivery interval. Conversely, by compressing the delivery interval, the information density may be significantly increased which may be desirable in certain situations.

In response to the recognized need to alter the performance interval of recorded material, prior operating structures have been proposed. Specifically, structural apparatus for varying the interval of recorded material from the interval of the original delivery are disclosed in U.S. Pat. 2,886,650 (Fairbanks et al.) entitled Recording Device and 3,022,383 (Springer) entitled Rotatable Electromagnetic Transducer System. In addition to the above structures, other forms of timevariation apparatus have been proposed, as for use in the communications field to conserve time in the transmission of intelligence. Generally, the systems as previously proposed, exemplified by the above-referenced patents, variously utilize signal sampling techniques, changes in recording rates, multiple recordings and so on to accomplish the desired change in the delivery time interval.

Although various techniques for changing the delivery interval of a sound sequence have been recognized for some time, these techniques have not generally come into widespread commercial use for applications requiring reasonably good fidelity. Generally, the limited use has resulted because the conventional techniques for changing the delivery interval of a sound sequence have resulted in substantial distortion. While such distortion is disturbing, though tolerable in certain applications, in others it simply may not be tolerated. Some improvement has been attained by using high fidelity processing equipment. However, even with very high quality apparatus, distortion remains, not only evident but is usually quite disturbing to the listener.

In accordance herewith, it has been discovered that one of the major contributing factors in the distortion of sounds that are recorded in an altered time interval is echoes produced from the original delivery. The human ear apparently is accustomed to inherent echo patterns which exist in almost every living environment. However, in the course of varying the time interval for a sound sequence, the inherent echo patterns are altered considerably from the natural situation. As a consequence, it has been discovered that in processing a sound sequence to vary the delivery interval, the echo patterns are largely responsible for the distorted reproduction. Accordingly, a system as disclosed herein incorporates structure for providing a substantially undistorted sound-' sequence (containing essentially no echoes) from an original delivery, which sound sequence is then converted to an electrical signal, processed by a time-variation apparatus and subsequently recorded for delivery in a time period differing from the interval of the original delivery.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, which constitutes a part of this specification, exemplary embodiments exhibiting various objectives and features hereof are set forth, specifically:

FIG. 1 is a block diagram illustrative of the present system of attaining a time-varied recording;

FIG. 2 is a sectionalized elevational and diagrammatic view of a system incorporating the present invention; and

FIG. 3 is an enlarged fragmentary sectional view of the structure of FIG. 2.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT As required, a detailed illustrative embodiment of the invention is disclosed herein. The embodiment exemplifies the invention which may, of course, be embodied in various other forms, some of which may be radically different from that illustrated herein. However, the specific structural and functional details disclosed herein are representative and they provide a basis for the claims herein which define the scope of the present invention.

Referring initially to FIG. 1, the recording process hereof includes a sequence of steps, the result of which is to provide a sound recording with an interval which is varied from that of the source or live performance. For example, the live or originating performance as represented by theblock 12 may be a lecture, a discussion, a performance or so on which produces a sequence of audible'sound material during a time interval that, for one reasonor another is undesirable.

In accordance herewith, the audible sounds of the live performance are selectively isolated to provide a fragment thereof which is substantially free of echoes as indicated by the block 14. The undistorted fragment is then converted to an electrical signal as indicated by the block 16 which'is processed to alter the delivery interval, in a step as represented by the block 18 and which may include time-displaced recording operations. Finally, the processed signal (manifest during a predetermined interval) is recorded in the step as indicated by the block 20. Subsequently, the recorded performance may be 'variously used for any of various purposes, as indicated=above.

An exemplary'structure for performing the process as described with reference to FIG. 1 is illustrated in FIG. 2 and will now be considered in detail. Recognizing that the source or origin of the sound to be recorded may vary widely, the human voice serves illustratively in that regard as provided by a subject 22. To accommodate the situation in which the sound that is to be processed originates from several different subjects, a plurality of individual sound units A through N are represented. Essentially, the sound unit A is designated as unit 24 while the similar sound unit N is designated as unit 26.

Functionally,::each of the sound units incorporate structure for providing at least a fraction of the sound produced by" the. subject, e. g. subject 22, which fraction is substantially.undistorted by any echoes. The units further incorporate structure for converting the undistorted sound to a representative electrical signal. The individual signals from the sound units,

e.g. sound units

24 and 26, are applied to an audio signal mixer 28, as well known in the prior art, for combination into a compound, substantially undistorted audio signal.

The output from the mixer 28 is applied to a signal variation apparatus 30 which may take any of a variety of well-known specific forms. For example, the signal variation apparatus may utilize any of a wide variety of prior techniques to compress or expand the interval of a sequence of sounds, as manifest by an electrical audio signal. In the specific system as disclosed, the signal variation apparatus comprises a magnetic recording apparatus incorporating a moving magnetic head, as disclosed in US. Pat. No. 2,886,650 or US. Pat. No. 3,022,383 for example, to accomplish the time-interval compression or expansion.

The time-varied signal from the apparatus 30 is finally applied to a magnetic-tape recording system 32 for producing the desired recording within the desired time interval. Of course, a variety of magnetic, or other recording systems, may be employed within the system hereof.

Considering the similar individual sound units A through N in somewhat greater detail, reference will now be made specifically to the structure illustrated for the unit A, as depicted within the block 24. The subject 22, functioning as the source of the sound sequence during an original delivery, directs his voice into the small end of an exponential born 34. The horn is provided of sonic material and may be generally annular in lateral configuration.

As indicated, the horn 34 is supported in the circular, flat wall 35 of a somewhat-conical enclosure 36 defining a closed conical chamber 38. The exponential horn 34 is concentrically mounted within the chamber 38 and also aligned with a series of circular apertured baffles 40, 42, and 44 of diminishing circumference. At the apex 46 of the conical enclosure 36 (opposed to the wall 35) a microphone 48 is mounted concentrically and aligned with

central apertures

50, 52 and 54 in the

baffies

40, 42 and 44, respectively.

The conical enclosure 36 as well as the

baffles

40, 42 and 44 may be provided of rigid sound material, e.g. composition material, plastic and so on. The entire interior of the enclosure 36 (including all exposed surfaces) and the

baffles

40, 42 and 44 are covered with sound-absorbing structures. Specifically, for example, in the illustrative embodiment, the internal surfaces of the chamber 38 receive pyramidally shaped foam members 58 (FIG. 3) affixed so that the bases thereof abut the structural surfaces. Specifically, as indicated in FIG. 3, the pyramidal members 58 are affixed to the baffle 40, extending substantially perpendicularly to the plane thereof. As indicated, the members 58 may be formed of plastic foam; however, other soundabsorbing material, e.g. felt, fiber material and so on may also be employed.

The microphone 48 is connected to an amplifier 60 for amplifying the sound-representative, or audio signals. The amplifier 60 has an equivalent in each of the other sound units, e.g. unit 26, and the outputs from all of the amplifiers are coupled to the mixer 28. Accordingly, the output from the mixer 28 comprises a composite electrical signal representative of a combination of the sounds supplied to each of the individual units, in a substantially echoless form.

In using the system of FIG. 2, the sound sources, e.g. subject 22, are aligned with the small open ends of each exponential horn 34. Of course, in some situations, a single speaker may be the sole source of the originaldelivery sound sequence. Alternatively, in other situations a group may use a single sound unit A or a large anechoic chamber (as known in the sound art) may be employed to completely enclose the originating sound source or sources.

The sound emanating from the speaker 22 (as well as other speakers aligned with other units) propagates in all directions and, accordingly, a portion thereof enters the horn 34 for matching introduction into the enclosure 36. The sound passing from the horn 34 tends to be a select segment of the original sound energy and is propagated from the large end of the horn 34 in a distributed pattern. A large portion of the energy emanating from the horn 34 impinges upon surfaces carrying the pyramidal sound-deadening members 58 and is absorbed within and between such members so that no echoes or reflections are produced.

A portion of the sound energy from the horn 34 also passes through the aperture 50, then the aperture 52 and the aperture 54 to actuate the microphone 48. The internal surfaces of the

apertures

50, 52 and 54 may comprise felt or other sound-absorbing material to avoid any reflections therefrom.

Each chamber adjacent the

baffles

40, 42 and 44 absorbs or dissipates any energy that is not passed through the baffle. Accordingly, the sound-energy passing from the horn 34 through the

apertures

50, 52 and 54 to actuate the microphone 48, represents a substantially undistorted or echoless fragment of the original sound energy. That fragment of energy is converted or sensed as an electrical signal by the microphone 48 and amplified by the amplifier 60 for processing in accordance herewith.

The audio signal, as provided from the amplifier 60, (along with any other similar signals) passes through the mixer 28 and is applied to the signal variation apparatus 30 which, in the disclosed embodiment, utilizes a moving-head magnetic structure in cooperation with magnetic recording tape to accomplish an expansion or contraction (with respect to time) of the audio signal sequence. A control knob 64 (along with other controls not shown) is employed to control the speed of operating components within the apparatus 30 as well as the direction of rotation in order to accomplish the contraction or expansion and the degree thereof. The details of such structure may be as set forth in the abovereferenced U.S. Pat. Nos. 2,886,650 and 3,022,383.

The output from the apparatus 30 is an electrical audio signal sequence provided on a time base which differs from the time base of the original delivery. For example, the original delivery may take the form of a lecture or speech, consuming for example a total interval of 37 minutes. However, by selective control of the signal variation apparatus 30, the interval of the speech may be reduced to a precise interval of thirty minutes. In accordance herewith, it has been discovered that by providing the sound from the original delivery in a substantially echoless form, then employing such a form to develop the audio signal for processing in the apparatus 30, not only are the tonal qualities of the original delivery substantially preserved but furthermore the processed audio signal enables reproduction with relatively good fidelity. The audio signal so produced and provided from the apparatus 30 is accordingly recorded by the recording system 32. It may, therefore, be seen that in accordance with the principles hereof, effective time-scale changes can be accomplished in recorded material either as a matter of convenience or for time economy. Of course, as indicated above, various structures may be employed to accomplish such re corded material. Recognizing the variations that are possible to accomplish such, the scope hereof shall be as defined by the claims set forth below.

What is claimed is: 1. A system for reproducing sounds in a different time interval than the interval of the original delivery, comprising:

means for isolating at least a fraction of the sound sequence of an interval of said original delivery, to provide an undistorted sound sequence including substantially no echoes from said original delivery;

microphone means for sensing energy of said undistorted sound sequence in the form of an electrical audio signal;

signal processing means for varying said audio signal to provide a time-variation signal in which said sound sequence is provided in said different time interval;

and

recording means for recording said time-variation signal for subsequent delivery in said different time interval.

2. A system according to claim 1 wherein said means for isolating comprises an anechoic chamber for receiving sounds of the original delivery and wherein said microphone means for sensing is positioned to receive said undistorted sound.

3. A system according to claim 1 wherein said signal processing means includes a moving head magnetic recording structure.

4. A system according to claim 1 wherein said means for isolating includes a substantially closed chamber of sound impenetrable material; a sound-absorbent liner on the interior of said chamber and means for introducing sound from said original delivery into said chamber.

5. A system according to claim 4 wherein said soundabsorbent liner includes a plurality of raised figures of sound-absorbing material.

6. A system according to claim 5 wherein said figures comprise pyramidal shapes.

7. A system according to claim 4 wherein said signal processing means includes a moving head magnetic recording structure.

8. A system according to claim 5 wherein said recording means comprises a magnetic tape recorder.

9. A method of recording sounds to occupy a different time interval than the interval of the original delivery, comprising the steps of:

isolating at least a fraction of the sound sequence from said original delivery to provide an undistorted sound sequence;

sensing the energy of said undistorted sound sequence in the form of an audio signal for said interval of the original delivery;

varying the interval of said audio signal to said different time interval to provide a time-variation signal; and

recording said time-variation signal for subsequent playback.

10. A method according to claim 9 wherein said step of varying the interval comprises compressing the interval by magnetic recording techniques.

11. A method according to claim 10 wherein said isolating step comprises introducing the sound sequence of the original delivery into an anechoic chamber.

Claims

1. A system for reproducing sounds in a different time interval than the interval of the original delivery, comprising: means for isolating at least a fraction of the sound sequence of an interval of said original delivery, to provide an undistorted sound sequence including substantially no echoes from said original delivery; microphone means for sensing energy of said undistorted sound sequence in the form of an electrical audio signal; signal processing means for varying said audio signal to provide a time-variation signal in which said sound sequence is provided in said different time interval; and recording means for recording said time-variation signal for subsequent delivery in said different time interval.

9. A method of recording sounds to occupy a different time interval than the interval of the original delivery, comprising the steps of: isolating at least a fraction of the sound sequence from said original delivery to provide an undistorted sound sequence; sensing the energy of said undistorted sound sequence in the form of an audio signal for said interval of the original delivery; varying the interval of said audio signal to said different time interval to provide a time-variation signal; and recording said time-variation signal for subsequent playback.