text: this disclosure of the invention is submitted in furtherance of the constitutional purposes of the u . s . patent laws &# 34 ; to promote the progress of science and useful arts &# 34 ; ( article 1 , section 8 ). fig1 shows an animal game call 10 in the form of a diaphragm call . the diaphragm call 10 is intended to be placed completely within the mouth of the person using the call . the diaphragm call 10 includes a peripheral , flexible , moldable edge 12 , which may comprise a reenforced plastic or fabric material . in one embodiment , the flexible , moldable material comprises reenforced adhesive - backed tape which is folded over onto itself to create a top side 14 and a bottom side 16 with the two sides being joined and secured in place at the respective adhesive - backed sides . the diaphragm call 10 further comprises a rigid frame 18 which is generally in the form of a u - shaped member . in one embodiment , the frame member 18 is formed by folding an oval - shaped piece of material , such as aluminum , back onto itself to form a bottom frame half 19 and a top frame half 20 . the bottom frame 19 and the top frame 20 are combined to form opposed frame sides 17a , 17b which generally define the frame width . a membrane 22 , preferably in the form of a latex membrane , is secured between the first frame side 17a and the second frame side 17b . the latex membrane 22 is held within the frame 18 so that the membrane 22 is under tension . when under the proper amount of tension , the latex membrane 22 will vibrate when air is forced across one side of the membrane surface to produce a sound . the frame 18 further includes an apex area 25 where the frame sides 17a and 17b join at the u - shaped area of the frame . a shelf 24 , in the form of an extending flange , integrally extends from the frame 18 generally at the apex location 25 . the shelf 24 extends in an arcing upward manner . the shelf or plate 24 extends upward from the apex location at an angle relative to the membrane . as shown in fig1 , 6 , and 7 , the shelf 24 extends over approximately 3 / 4 of the area of the latex membrane 22 . as can be seen , the shelf 24 has a shelf width that corresponds substantially to the frame width defined by opposed frame members 17a , 17b . fig2 shows a prior art diaphragm call , which of course does not include any upwardly extending shelf 24 as in the present invention . the prior art diaphragm call includes a peripheral , flexible piece of edge material 14 intended to be sealed against the roof of the caller &# 39 ; s mouth . the tongue of the caller urges the diaphragm call against the roof of the mouth to create a distance d 1 which , in part , determines the pitch of the sound made by the call when air a is forced across the latex membrane 22 . the gap for airflow between the person &# 39 ; s tongue and the latex membrane must be maintained at approximately 1 / 8 of an inch . since the tongue must be used to force the diaphragm upward against the roof of the caller &# 39 ; s mouth , the air channel through which air a is forced usually corresponds to the mid - portion of the person &# 39 ; s tongue , with the sides of the tongue forcing the diaphragm upward . since the palate of a given caller will vary depending upon the physiological makeup of the person &# 39 ; s mouth , the specific location of the diaphragm call ( i . e ., the forward / backward position of the call ) must vary to ensure that the distance d 1 remains optimal for emitting the proper sound and to seal the flexible edge of the diaphragm call against the palate . in comparison , the diaphragm call of the present invention , as shown in fig3 includes an integral , upwardly arcing and extending flange 24 which defines a distance d 2 . this distance remains constant unless the structure of the call is changed . as discussed above , the distance d 2 is one of the variables which affects the pitch of the sound emitted by the caller when air a is forced across the latex membrane . accordingly , the backward / forward orientation of the diaphragm call will not affect the pitch of the sound emitted when air a is forced across the latex membrane 22 . therefore , relative to the roof of a person &# 39 ; s mouth , the only variable that must be compensated for is that the peripheral flange 12 be sealed against the roof of the mouth so that air does not pass over the top of the game call . regarding sound pitch , tongue pressure on the latex diaphragm becomes the primary variable . as shown in fig1 the shelf 24 may be made of aluminum , which enables the shelf 24 to be bent and pivoted along pivot line 27 to vary the distance between the top surface of the latex membrane and the shelf 24 . the shelf or plate 24 is malleable and adjustable to vary the angle relative to the membrane 22 . this enables the caller to more easily adjust the pitch of the sound emitted from the diaphragm call 10 . the flange 24 is also beneficial in that it prevents the caller from putting excess upward pressure on the latex membrane 22 which may otherwise exceed the modulus of elasticity of the latex member and result in permanent deformation . the shelf 24 acts essentially as a barrier beyond which the latex membrane 22 cannot be forced . in compliance with the statute , the invention has been described in language more or less specific as to structural and methodical features . it is to be understood , however , that the invention is not limited to the specific features shown and described , since the means herein disclosed comprise preferred forms of putting the invention into effect . the invention is , therefore , claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents .