US2210415A - Sound collecting system - Google Patents

Sound collecting system Download PDF

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Publication number
US2210415A
US2210415A US182721A US18272137A US2210415A US 2210415 A US2210415 A US 2210415A US 182721 A US182721 A US 182721A US 18272137 A US18272137 A US 18272137A US 2210415 A US2210415 A US 2210415A
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US
United States
Prior art keywords
sound
diaphragms
waves
wave
line
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US182721A
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English (en)
Inventor
Edward W Kellogg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to NL54237D priority Critical patent/NL54237C/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US182721A priority patent/US2210415A/en
Priority to CH208021D priority patent/CH208021A/de
Application granted granted Critical
Publication of US2210415A publication Critical patent/US2210415A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
    • H04R1/342—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means for microphones
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/72—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using ultrasonic, sonic or infrasonic waves

Definitions

  • This invention relates to sound collecting systems, and more particularly to a microphone system of the directive type.
  • the primary object of my present invention is to provide an improved sound collecting system of the type under consideration which will be free from the foregoing and other similar defects of prior art systems.
  • Another object of mypresent invention is to provide an improved sound collecting system which need not be aimed with extreme accuracy toward the sound source in order to receive sound therefrom in the desired direction.
  • Still another object of my present invention is to provide an improved sound collecting system 5 of the type described which will have a characteristic free from objectionable resonant peaks.
  • I employ a linearly disposed wave propagating medium along which audio frequency waves are transmitted with a velocity substantially equal to the velocity of sound in free air.
  • I make provision for a certain degree of coupling between said wave propagating medium and the surrounding air such that sound waves in the surrounding air will give rise to sound waves in the linear propagation medium.
  • This coupling may be continuous or at a series of discrete points, such points being preferably spaced several per wave length of the highest frequency sounds to be collected. If a sound wave in the surrounding air is traveling parallel to the transmission medium, a wave is started in said medium, and this wave becomes reinforced at each point of coupling and builds up to relatively large amplitude by the time it reaches the end of the medium.
  • I provide what I term a line type of sound pick-up system, by which I mean a system in which a number of sound sensitive elements are acted upon in sequence by the wave as it progresses, provision being made for combining the outputs of these elements with proper time intervals to produce in-phase addition, provided the direction of the sound is parallel to the line along which the elements are disposed.
  • the waves on the line may be either acoustic or mechanical.
  • the line may consist of a hollow tubular element to one end of which is connected a suitable microphone, and the other of which is provided with suitable damping material for clamping sound waves reaching the latter end.
  • the line may consist of a fine wire helix, or a long, thin wire or string subject to transverse vibrations.
  • the sound sensitive elements may consist of a num- I ber of diaphragms or the like by which vibrations are communicatedfrom the surrounding air to the transmission line, or they may simply consist of perforations through a wall of the tubular transmission line through which sound enters an otherwise shielded chamber.
  • the type of directive sound collecting system which is the subject of my present invention may be compared to a wave antenna, as distinguished from what I term the area type" of sound collecting system disclosed in my copending application Serial No. 182,720, filed December 31, 1937.
  • Figure 1 shows one modification of a sound collecting system employing a tubular transmission line according to my present invention
  • Figure 2 is ,a similar view of a modified form of this type of sound collecting system
  • Figure 3 is a modification of my invention employing a fine wire helix as the transmission line
  • FIG. 4 is still another modification wherein a transversely vibratable transmission line is employed
  • Figure 5 is a view, partly in plan and partly in section, of still another form of my invention.
  • Figure 6 is a sectional view thereof taken on the line VI-VI of Figure 5.
  • a tubular member or pipe I of relatively great length and small diameter provided with a series of longitudinally spaced, small openings 3 along its length by means of which communication is established between the atmosphere and the interior of the tubular member I, the small air columns in the openings 3 serving as the coupling means between the atmosphere and the interior of the tube I.
  • the diameter of the tube I should be small in comparison to the shortest wave lengths to be received, while the length should be of the order of a wave length or more of the lowest frequency sounds to be received.
  • a suitable microphone or other sound responsive device 5 Coupled to the end of the tubular member I adjacent the openings 3 is a suitable microphone or other sound responsive device 5, while the opposite end of the tube or pipe I is preferably closed by a cover I and filled with a suitable sound absorbing or damping material 9, a sufiicient length being filled with such absorbing material to substantially prevent reflection of sound waves reaching said end.
  • a sound wave such as that shown at A in Fig. 1 travelling through the atmosphere in the direction of the arrow and substantially parallel to the length of the pipe I will establish waves inside the pipe I through the openings 3, and, if the sound waves within the pipe I travel at the same velocity as the waves outside of the pipe, or in the atmosphere, those inside of the pipe I are built up or augmented'by additional energy communicated from without through each of the openings 3 as they progress toward the microphone 5.
  • the damping material 9 is provided so that waves built up within the pipe I in the opposite direction will be absorbed. Very small openings 3 will sufiice to build up a reasonable intensity at the microphone 5. For example, in
  • the disturbances produced by the secondary diaphragms II will add up and reach the diaphragm of the microphone 5 (in this case illustrated as a condenser microphone) in phase, provided the sound waves A travel parallel to the tube I in the direction of the arrow. If the sound wave A travels in the opposite direction, a wave is built up in the tube I which reaches its full amplitude at the left hand end of the tube, where it is absorbed by the damping material 9, and, therefore, does not appreciably affect the microphone 5.
  • each of the secondary diaphragms II is covered with a shield I! which protects the diaphragms II from external air pressure.
  • the bell cranks I3 may be pivotally mounted on the shields I'I.
  • Fig. 3 The principal reason for using a tubular transmission line is the ease with which equality of velocity of propagation inside and outside may be obtained.
  • Fig. 3 This device should have the same directive property as those shown in Figs. 1 and 2-and employs a solid body to conduct the waves imparted to it by a number of diaphragms.
  • the system consists of a supporting frame 2
  • the helix 23 should have such characteristics that the velocity of propagation of longitudinal waves along it shall be approximately equal to that of ture and thus cause excessive attenuation of high frequency waves.
  • the separation of the diaphragms must not exceed about 1/11- wave lengths of the highest frequency to be transmitted.
  • the separation of the diaphragms must not exceed about 1/11- wave lengths of the highest frequency to be transmitted.
  • the diaphragms should not be more than inch apart.
  • a wave similar to the wave A in the atmosphere in passing from left to right successively actuates the diaphragms 21 which build up a longitudinal wave in the helix 23 that actuates the microphone 5 (in this case shown as of the dynamic type) carried by the framework 2
  • the left hand end of the helix 23 is terminated in a chamber 29 filled with a suitable damping fluid 3 I, such as oil, which absorbs waves built up along the helix from right to left, the chamber 29 being also supported by the frame 2
  • a very light and flexible diaphragm 33 is attached which retains the oil or other damping fluid 3
  • Fig. 3 I have shown the damped line terminated in a perforated plunger of very light weight which is designed to afford as nearly as practicable a resistance to motion (under average conditions as to temperature) equal to the characteristic impedance of With such a concentrated resistance at the end, a much shorter damped line will suffice.
  • the concentrated resistance may be used alone, but the combination will, in general, function more satisfactorily, throughout the frequency range, will be easier to adjust for minimum reflection, and will be less affected by tem perature.
  • the length of the active portion of the line (in other words, that part to which the diaphragms are attached) will depend on the degree of directivity desired. Useful discrimination can be obtained with a length as small as a half wave length, but preferably the line should be a wave length or more long at the lowest important frequency. So far as convenience is concerned, the length of a device of this kind would, in many cases, be compensated by the fact that the other dimensions are small compared with those of the area type of directive pick-up referred to above.
  • Fig. 4 there is shown a modification of my invention wherein a series of diaphragms l5, pivotally supported ona bar orthe like 35 through the bell cranks l3, produce transverse vibrations of the transmitting line, or wave propagating element.
  • the transmission line in this case, might consist of a long, thin bar 31 of proper stiffness and mass to have a velocity of propagation equal to that of sound waves in the air, but such a line is not altogether satisfactory because the velocity is not the same for all frequencies.
  • a preferable form of line consists of a loaded string or very flexible wire subjected to sufiicient tension to give it the desired wave velocity.
  • the tension can be applied to the wire or the like 31 by means of an unloaded string or wire 39, one end of which is connected to the right hand end of the member 31, and the other end of which is connected to an adjustable device, such as a wing nut and screw, 4
  • the right hand end of the element 31 is also connected to a suitable microphone 5, and the left hand end thereof is terminated in a damping medium similar to that described in connection with Fig; 3, the diaphragm for confining the damping fluid in this case being designed to exert minimum restraint to transverse waves.
  • the primary diaphragms [5 are coupled to the transmission element 31 through the bell cranks l3 and impart transverse vibrations thereto in response to sound waves passing from left to right, as indicated by the dotted line 31, which add up to actuate the microphone 5.
  • a wave passing from right to left will produce transverse vibrations in the member 31' which reach their maximum amplitude at the left hand end where they are absorbed by the damping medium 3!.
  • the diaphragms l5 In order that the system shall not act as a mechanical filter, the diaphragms l5 must not load the string or other similar member 31 unless their spacing is a small fraction of the wave length of the highest frequency to be transmitted by the system. Whatever the spacing of the coupling elements, it is essential that they shall not load the transmission line in such a way as to cause the velocity of propagation to differ materially from the velocity of sound in air, nor to cause the velocity to be materially different at difl'erent frequencies in the audio range.
  • the springs may be omitted and the bell cranks l3 connected to the transmission element 31 similarly to the connections of the horizontal arms of the bell cranks l3 to the secondary diaphragms H in the modification of Figure 2.
  • the effect of so connecting the bell cranks l3 to the bar or wire 31 would be to add a concentrated inertia load or mass at each of the points of connection between it and the several bell cranks, the added mass due to the bell cranks l3 and the diaphragms l5 being included gin the effective mass per unit from undesired directions.
  • the general requirements as to loading the line and spacing of the coupling elements between the atmosphere and the line are essentially the same.
  • too great spacing of the coupling elements will have the tendency to cause the system to be sensitive, at certain frequencies, to waves coming
  • the spacing is a half wave length (at a given frequency) or a whole number of half wave lengths, waves will build up at the microphone end of the line as effectively for external Waves traveling from right to left as for waves traveling from left to right.
  • a sound collecting system comprising a relatively long tubular member having a plurality of spaced, small openings along its length whereby to provide communication between the interior of said tubular member and the atmosphere, and a microphone connected to one end of said tubular member and arranged to be actuated by sound waves set up in said tubular member, said openings affording an inlet into said tubular member for sound waves in the atmosphere surrounding said member whereby a wave passing along said tubular member sets up vibrations therein through said openings.
  • a sound collecting system characterized in that tubular member is of 'the order of a wave length long for the lowest frequency sounds intended to be picked up by said system, and characterized further in that said openings are so spaced apart that the waves set up in said tubular member through each of them will be in phase.
  • a sound collecting system comprising a relatively long tubular member having a plurality of spaced, small openings therein along its length, a diaphragm closing each of said openings, a second diaphragm associated with each of said first named diaphragms, said second.- diaphragms being arranged outside of said tubular members and disposed in a manner to be successively acted upon by a sound wave travelling through the atmosphere, means coupling said: second named diaphragms to their respectively associated first named diaphragms whereby actuation of said second named diaphragms will eifect actuation of said first named diaphragms to set up pressure variations within said tubular member, a microphone connected to one end of said tubular memher and arranged to be actuated by the waves set up in said tubular member in response to actuation of said first named diaphragms, and sound wave absorbing means at the other end of said tubular member for absorbing waves reaching said last named end.
  • a sound collecting system characterized by the addition of means for shielding each of said first named diaphragms against direct actuation thereof by sound waves in the atmosphere.

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  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Exhaust Silencers (AREA)
US182721A 1937-12-31 1937-12-31 Sound collecting system Expired - Lifetime US2210415A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL54237D NL54237C (pl) 1937-12-31
US182721A US2210415A (en) 1937-12-31 1937-12-31 Sound collecting system
CH208021D CH208021A (de) 1937-12-31 1938-12-31 Vorrichtung mit Richtwirkung zur Aufnahme von Schallwellen und zur Umwandlung derselben in elektrische Schwingungen.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US182721A US2210415A (en) 1937-12-31 1937-12-31 Sound collecting system

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US2210415A true US2210415A (en) 1940-08-06

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CH (1) CH208021A (pl)
NL (1) NL54237C (pl)

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2418964A (en) * 1945-07-09 1947-04-15 David L Arenberg Electromechanical apparatus
US2474384A (en) * 1944-04-28 1949-06-28 Philco Corp High-frequency radiant energy absorbing device
US2485405A (en) * 1944-04-21 1949-10-18 Stromberg Carlson Co Dipole microphone
US2528546A (en) * 1944-08-04 1950-11-07 Richard H Ranger Directional sound detection system
US2611867A (en) * 1946-08-31 1952-09-23 Alford Andrew Slotted winged cylindrical antenna
US2739659A (en) * 1950-09-05 1956-03-27 Fred B Daniels Acoustic device
US2750567A (en) * 1952-03-15 1956-06-12 Rca Corp Mechanical resonator termination
US2761137A (en) * 1946-01-05 1956-08-28 Lester C Van Atta Solid dielectric waveguide with metal plating
US2789651A (en) * 1950-09-05 1957-04-23 Fred B Daniels Acoustic device
US2806544A (en) * 1953-10-15 1957-09-17 Albert L Witchey Sound sources for microphone calibration
US2808584A (en) * 1954-01-29 1957-10-01 Bell Telephone Labor Inc Directional radiator
US2856022A (en) * 1954-08-06 1958-10-14 Electro Sonic Lab Inc Directional acoustic signal transducer
US2861646A (en) * 1953-07-08 1958-11-25 Bell Telephone Labor Inc Direction finder utilizing elastic waves of transverse mode
US2928490A (en) * 1957-04-30 1960-03-15 Sennheiser Electronic Sound directing apparatus
US2939922A (en) * 1955-05-26 1960-06-07 Gorike Rudolf Directional microphone having a low susceptibility to shock and wind
US3054472A (en) * 1955-01-31 1962-09-18 John V Atanasoff Sound discriminating device
US3142034A (en) * 1959-02-10 1964-07-21 Miguel C Junger Elastic wave radiator and detector
US3278772A (en) * 1959-08-10 1966-10-11 Csf Acoustic wave generator
US4757546A (en) * 1985-11-19 1988-07-12 Kabushiki Kaisha Audio-Technica Narrow directional microphone
US4789044A (en) * 1985-11-19 1988-12-06 Kabushiki Kaisha Audio-Technica Narrow directional microphone
USD444143S1 (en) 1999-10-08 2001-06-26 Telex Communications, Inc. Microphone
USD851633S1 (en) * 2017-06-12 2019-06-18 Toa Corporation Microphone with built-in speaker

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1272375B (de) * 1964-12-01 1968-07-11 Akustische Interferenzmikrophon mit einem vor der Membran des Wandlersystems angeordneten Rohr

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2485405A (en) * 1944-04-21 1949-10-18 Stromberg Carlson Co Dipole microphone
US2474384A (en) * 1944-04-28 1949-06-28 Philco Corp High-frequency radiant energy absorbing device
US2528546A (en) * 1944-08-04 1950-11-07 Richard H Ranger Directional sound detection system
US2418964A (en) * 1945-07-09 1947-04-15 David L Arenberg Electromechanical apparatus
US2761137A (en) * 1946-01-05 1956-08-28 Lester C Van Atta Solid dielectric waveguide with metal plating
US2611867A (en) * 1946-08-31 1952-09-23 Alford Andrew Slotted winged cylindrical antenna
US2739659A (en) * 1950-09-05 1956-03-27 Fred B Daniels Acoustic device
US2789651A (en) * 1950-09-05 1957-04-23 Fred B Daniels Acoustic device
US2750567A (en) * 1952-03-15 1956-06-12 Rca Corp Mechanical resonator termination
US2861646A (en) * 1953-07-08 1958-11-25 Bell Telephone Labor Inc Direction finder utilizing elastic waves of transverse mode
US2806544A (en) * 1953-10-15 1957-09-17 Albert L Witchey Sound sources for microphone calibration
US2808584A (en) * 1954-01-29 1957-10-01 Bell Telephone Labor Inc Directional radiator
US2856022A (en) * 1954-08-06 1958-10-14 Electro Sonic Lab Inc Directional acoustic signal transducer
US3054472A (en) * 1955-01-31 1962-09-18 John V Atanasoff Sound discriminating device
US2939922A (en) * 1955-05-26 1960-06-07 Gorike Rudolf Directional microphone having a low susceptibility to shock and wind
US2928490A (en) * 1957-04-30 1960-03-15 Sennheiser Electronic Sound directing apparatus
US3142034A (en) * 1959-02-10 1964-07-21 Miguel C Junger Elastic wave radiator and detector
US3278772A (en) * 1959-08-10 1966-10-11 Csf Acoustic wave generator
US4757546A (en) * 1985-11-19 1988-07-12 Kabushiki Kaisha Audio-Technica Narrow directional microphone
US4789044A (en) * 1985-11-19 1988-12-06 Kabushiki Kaisha Audio-Technica Narrow directional microphone
USD444143S1 (en) 1999-10-08 2001-06-26 Telex Communications, Inc. Microphone
USD851633S1 (en) * 2017-06-12 2019-06-18 Toa Corporation Microphone with built-in speaker

Also Published As

Publication number Publication date
NL54237C (pl)
CH208021A (de) 1939-12-31

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