a hearing aid 1 is shown in fig1 having components therein arranged and mounted in accordance with the principles of the present invention . the hearing aid 1 has a housing comprised of two joined shells 2 and 2a . the housing has a battery drawer 3 at the lower portion , and has a crook at anupper portion by means of which the hearing aid 1 is worn behind the ear . the free end of the crook 4 is connected to a conduit 5 terminating in an earpiece 6 which can be inserted into the ear canal so that amplified acoustic signals proceed directly into the inner ear . a regulator wheel 8 for the volume is disposed above a locking flap 7 , and a switch 9 is disposed below the flap 7 at the rear of the device , which assumes a convex curve . the components contained in the interior of the hearing aid 1 are shown in detail in fig2 . the hearing aid 1 operates in a conventional manner withan aural signal entering the device through an opening 10 and proceeding toa microphone 11 wherein the signal is converted into electrical signals which are amplified in an amplifier 12 powered by means of a battery 13 . the electrical signals are reconverted into aural signals in an earphone 14 . the amplified signals proceed through a sound - conducting channel 15 connected to another channel 16 within the crook 4 . the channel 16 is connected to the conduit 5 ( not shown in fig2 ). the amplifier 12 has a number of components designated 17 which are attached to a mounting plate 18 . a spring contact 20 together with a complimentary opposing contact ( not visible in fig2 ) are connected to the battery 13 for receiving power therefrom . in addition , the plate 18 carries a mounting unit 21 at its edge closest to the convex side of the housing 1 . the mounting unit 21 contains regulators 22 , 23 , 24 and 25 and an acoustic coil 26 combined therein . the coil 26 can be switched on by means of the switch 9 in the position t shown in fig1 the switch effecting connecting of the amplifier 12 to the microphone 11 when in the position m shown in fig1 . the hearing aid is switched off when the switch 9 is in the switch position o . the regulators 22 through 25 contained in the mounting unit 21 are accessible by opening the flat 7 ( which is movable to the position 7a shown in dashed lines in fig2 ) which exposes the regulators 22 through 25 permitting them to be set by means of their respective actuation elements 27 , 28 , 29 and 30 ( shown in fig3 ). the regulator 22 functions for adjustment of peak cut - off ( pc ). as indicated by the direction of the screw slot of its actuation element 27 ( which can be set with a screwdriver ), this regulator is switched off in fig3 . the regulator 23 serves for regulating automatic gain control for the amplifier 12 and may be set to a maximum amplification of 90 db . as shown by the other numerals in fig3 settings of 60 or 75 db could also be selected . the regulator 24 functions to control the transmission of lower frequenciesin the amplifier 12 . when the regulator 24 is set as shown in fig3 at position l , transmission of lower frequencies is enhanced . uniform transmission of all frequencies can be achieved at setting n , i . e ., normal . the regulator 25 , which is switched off in the position shown in fig3 functions to control transmission of high frequencies in the amplifier 12 . when set to position h , transmission of higher frequencies is enhanced . again , uniform trnasmission of all frequencies is achieved at setting n . the mounting unit 21 has a unitary mounting plate 35 to which the regulators 22 through 25 and the acoustic coil 26 are attached . this component , shown separately in fig5 in a side view , has recesses 50 , 51 , 52 and 53 into which the regulators 22 through 25 respectively fit . the unitary mounting plate 35 also has a projection 36 which is received in a complimentary shaped eyelet 37 formed in the acoustic coil component . the regulators 22 through 25 are disposed side by side along a curved surface corresponding to the rear of the housing . as shown in fig4 the winding 38 of the acoustic coil 26 is injected intoa synthetic member 39 having a projection 40 as well as the eyelet 37 . the projection 40 closes the openings 50 through 53 for the regulators 22 through 25 from the remaining mounting space of the amplifier . the opposite side of the openings is closed by the unitary mounting plate 35 itself . an upper portion 41 of the plate 35 forms one side of the receptacle for the regulators 22 through 25 at the side facing the viewer in fig2 . the mounting plate 18 for the amplifier 12 forms the other side , which is still open after assembly . fastening of the unitary mounting plate 35 , with the coil and regulators carried thereon , is achieved by means of clips 42 , 43 , 44 and 45 carried on the regulators 22 through 25 which project from the regulators after the regulators have been inserted into the plate 35 . the clips 42 through 45 extend through the plate 18 and are soldered as indicated at 46 so as to simultaneously fasten the components and provide an electrical connection to the circuit for the amplifier 12 . mechanical stabilization of the unitary mounting arrangement is achieved bythe curvature of the projection 40 , the curve indicated at 47 in fig5 aswell as by curvature of the plate 35 . the plate 35 has an additional recess48 in which the projection 36 which receives the eyelet 37 is disposed . therecess 48 has a shape matched to the eyelet 37 . the receptacles 50 , 51 , 52 and 53 for the regulators 22 through 25 have shapes which are matched to the shapes of the regulators . the combined unit consisting of the unitary plate 35 , the acoustic coil 26 and the regulators contained therein is already mechanically durable when assembled , and can be attached to the mounting plate 18 of the amplifier 12 as a single physical unit . simplification and further mechanical stabilization of the assembly can be achieved in another embodiment shown in sectional view in fig6 wherein the unitary mounting plate 35 and the synthetic member 39 shown in fig4 are combined in a single component , referenced at 56 in fig6 . the portion of the plate 35 referenced at 55 in fig4 is omitted in the embodiment shown in fig6 to permit insertion of the regulators 22 through2 5 in their respective openings in the component 56 prior to covering the openings with the plate 18 during final assembly . this is in contrast to insertion of the regulators 22 through 25 from the curved side47 shown in the embodiment of fig5 . by combining the regulators 22 through 25 and the acoustic coil 26 in a single unit , the actuation elements 27 through 30 are always precisely aligned with the proper labeled regulator aperture so that additional alignment procedures are not required . in addition to being guided and supported at the solder locations 46 , the regulators 22 through 25 are also guided and supported by the unitary mounting plate 35 . given actuation of the regulators by a screwdriver at the locations 27 through 30 , the regulators thus cannot be dislocated or the solder locations 46 broken . because the unit 21 is closed on all sides by electrically insulating material , the regulators 22 through 25 are not subject to the possibility of inadvertent contact with each other or with the surroundingelectrically conductive components 17 of the amplifier 12 , either in quiscent condition or upon energization . because the regulator aperture 41acts as a means for securing the regulators during soldering , the regulators 22 through 35 are automatically correctly adjusted relative to each other , so that subsequent adjustment means are not necessary . the acoustic coil 26 is secured to the unit 35 without the necessity of additional mounting structure which would otherwise have to be carried on the housing shell 2 or the amplifier 12 . the eyelet 37 and the projection 36 are easily manufactured by injection molding . final inspection of the amplifier 12 can be undertaken before incorporation in the housing shells 2 and 2a . the hearing aid constructed in accordance with the principles ofthe present invention is easy to service , because all functional componentsexcept the microphone 11 and the earphone 14 and the battery compartment 3 can be built - in and dismantled together with the amplifier 12 . although modifications and changes may be suggested by those skilled in theart it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art . the acoustic coil 26 is generally also known as tele - coil becuase it is mostly used with hearing aids for receiving induction signals originating in telephone receivers , to improve the ability of hearing impaired personsto understand telephone calls .