US1944720A - Microphone for the deaf - Google Patents

Microphone for the deaf Download PDF

Info

Publication number
US1944720A
US1944720A US475576A US47557630A US1944720A US 1944720 A US1944720 A US 1944720A US 475576 A US475576 A US 475576A US 47557630 A US47557630 A US 47557630A US 1944720 A US1944720 A US 1944720A
Authority
US
United States
Prior art keywords
diaphragm
microphone
microphones
carbon
casing
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
US475576A
Other languages
English (en)
Inventor
Sell Helmut
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.)
Siemens and Halske AG
Siemens Corp
Original Assignee
Siemens 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
Application filed by Siemens Corp filed Critical Siemens Corp
Application granted granted Critical
Publication of US1944720A publication Critical patent/US1944720A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R21/00—Variable-resistance transducers
    • H04R21/02—Microphones
    • H04R21/023—Microphones with more than one granular chamber

Definitions

  • Tile invention relates to a microphone for the In portable electrical apparatuses for the deaf, there are a series of requirements which in 5 theirtotality can only be satisfied by a compromise.
  • the object of the invention is to contrive an apparatus in which the various requirements are satisfied more completely than has hitherto been possible.
  • the requirement of as large a sound as possible without using a separate electrical amplification makes it? necessary to utilize in every case mechanical resonance.
  • the natural vibration of the microphone must therefore be situated in the range of the important or characteristic speech frequency band, which has distortions as a result.
  • characteristic speech frequency band I mean such portion of the complete frequency band as is sufficient to give intelligible speech reproduction, even though such reproduction may not be as accurate as if the entire speech frequency band were used.
  • To obtain greater loudness generally at least two microphones are used. These microphones are'normally tuned approximately alike, but the resonances naturally do not coincide.
  • the prepared casings must usually be surrounded by a casing of rectangular shape. It is also not possible to make the microphone cases very flat, although a very flat construction of thecontact bodies in itself is possible. This depends on the fact that the tuning of the diaphragms is greatly influenced by the air spaceunderneath. Very flat microphone casings are, for this reason, insensitive. The utilization of the space is consequently bad in both directions. On the one hand, the free surface of the sound receiving casing is much greater than the effective surface of the two microphone diaphragms, and, furthermore, the thickness of the sound receiver is necessarily over its whole extent at 7 least as great as the, separate microphones necessitate for reasons of snsitiveness.
  • This pick-up diaphragm is preferably of rec- 0 tangular shape and forms the one limiting wall of a flat rectangular box in which the carbon contact bodies are suitably arranged.
  • the resonance curve of such a vibration formation can be very favourably' formed for the present purpose, as it can be suited within wide limits to the requirements.
  • a band shaped oscillating surface that is, a rectangular plate which is clamped at its
  • Such a band has obviously a system of natural vibrations, namely, a strongly enunciated basic sound, and corresponding over-tones, agreeing essentially with the basic sound of the natural vibration of a cross strip element.
  • the length of the band is for the most part without influence. This applies also approximately for the case when the two short sides are also clamped, when the band is very long. If the band becomes shorter and shorter, then a great alteration takes place in the resonance curve.
  • a special advantage of the improved arrangement is the circumstance that with the fixing of the diaphragm, it is not necessary to arrange any contact make therewith.
  • a certain amount of difiiculty has arisen with ordinary microphones owing to the fact that the current through the diaphragm must be carried through the casing, and that contact dificulties are created owing to aluminium cases being used on account of the weight.
  • the improved arrangement permits any desired fixing of the circumference of the diaphragm without contact make. This circumstance permits a special space economizing and reliable fixing of the diaphragm, for example, by varnish.
  • This method of fixing has been proved particularly good with the new microphone, as the method provides a means of fixing free of cracking noises and ensures an intimate mechanical connection with the casing, so that the mass of the casing body is fully utilized and no vibration energy is lost by damping in the clamping.
  • a further advantage of the arrangement consists in the possibility of using any desired material for the diaphragm.
  • the conduction of the current is best carried out in the case of a non-conductor by a thin strip of carbon which is stuck on the diaphragm at a suitable position and covers the contact body at a suitable distance.
  • the current runs in this case from one contact body through the movable carbon contacts to the diaphragm through the carbon strip, over the movable contacts to the second body.
  • the conditions are particularly simple with the use of a homogeneous carbon plate as the diaphragm.
  • the different properties may be produced-by different kinds of grains or by different sizes with the same kind of grain.
  • Fig. 1 shows an elevation
  • Fig. 2 a section in the direction AB of Fig. 1
  • Fig. 3 is a section on the line C-D of Fig. 1.
  • the casing 1 of rectangular shape with suitably rounded comers contains inside, the two carbon blocks 2, 3, in the depressions 4, 5 of which are carried the carbon grains 6.
  • the casing 1 is finally closed with the cover 9 which is made thicker in the centre than at the edges, in order to attain the shape of a bulged pocket-book.
  • the cover 9 is provided with a series of cylindrical holes in order to conduct the sound coming from outside on to the carbon diaphragm.
  • the usual arrangement of two superposed covers is avoided, which in the use of separated microphone cases could not be obviated, and which take up a great deal of room since for acoustical reasons the outer cover had to be arranged at a certain distance from the perforated cover of the microphone casing.
  • the rectangular base surface of the case is considerably reduced.
  • Two contact pins 10 are arranged on the narrow side of the casing,- and. these are electrically connected with the carbon blocks 2, 3. On these pins are pushed the corresponding plug sockets provided on the connecting lines. Furthermore, a clip 11 in the form of a strip ofunetal provided with a globular end 12 is fixed on the back of the casing, so that the case may if necessary be hooked on to the clothing.
  • a transmitter of the class described consisting of a plurality of separate microphones preferably connected in series, a rectangular diaphragm having longitudinal and transverse resonances both substantially within the range of the characteristic speech frequency band to be transmitted, a case containing the diaphragm and the microphones, said diaphragm being common to the microphones and adapted to vibrate bodily as a whole to develop at least two different resonance frequencies of which the one, a longitudinal resonance, is determined chiefly by the length of the diaphragm and the other, 'a transverse resonance, by the width thereof.
  • a transmitter for the deaf comprising a plurality of separate microphones, a rectangular diaphragm common to said microphones and having longitudinal and transverse resonances'

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
US475576A 1929-08-17 1930-08-15 Microphone for the deaf Expired - Lifetime US1944720A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE360517X 1929-08-17

Publications (1)

Publication Number Publication Date
US1944720A true US1944720A (en) 1934-01-23

Family

ID=6294386

Family Applications (1)

Application Number Title Priority Date Filing Date
US475576A Expired - Lifetime US1944720A (en) 1929-08-17 1930-08-15 Microphone for the deaf

Country Status (3)

Country Link
US (1) US1944720A (enrdf_load_stackoverflow)
DE (1) DE616935C (enrdf_load_stackoverflow)
GB (1) GB360517A (enrdf_load_stackoverflow)

Also Published As

Publication number Publication date
GB360517A (en) 1931-11-12
DE616935C (enrdf_load_stackoverflow)

Similar Documents

Publication Publication Date Title
US2138036A (en) Compressional wave sender or receiver
US2122587A (en) Acoustic device
US2416314A (en) Electroacoustic transducer
US1944720A (en) Microphone for the deaf
US2262146A (en) Sound translating apparatus
US4027115A (en) Electroacoustic sound generator
US1711529A (en) Multiple-range sound-transmitting system
US1801521A (en) Loud-speaker horn
US1730411A (en) Herbert grove dorset
US1995461A (en) Dual sound reproducing device
US1863840A (en) Loud speaker apparatus and methods
US1893893A (en) Piano with loud speaker on secondary sound board
US1546749A (en) Telephone transmitter
US1730425A (en) Acoustic device
US1784596A (en) Closed-end resonating horn
GB298382A (en) Means for sending and receiving underwater sounds
US1863322A (en) Telephone pay station
US1715703A (en) Multiple-inlet horn
US1745937A (en) Acoustic device
US1730531A (en) Acoustic transformer
US1735905A (en) Microphone mounting
US2085073A (en) Sound translating device
US1986609A (en) Microphone
US2405225A (en) Submarine signal system
US2908772A (en) Electroacoustical transducer