turning now to the drawings , an in - wall speaker enclosure 10 is depicted , with reference to a conventional wall having spaced - apart , upright studs 12 , 14 , and wall board 16 spanning the studs 12 , 14 . the enclosure 10 is designed to fit between the studs 12 , 14 , and support a speaker assembly 18 ( see fig3 ) in a recessed condition relative to wall board 16 . the mounting also permits attachment of a conventional decorative grille ( not shown ) over the speaker assembly 18 to give a neat , finished appearance to the speaker unit . in more detail , the speaker enclosure 10 is made up of three major components , namely a frame 20 , housing 22 , and an expandable air chamber 24 . the frame and housing are of substantially quadrate configuration , and are adapted to interfit as described below . likewise , the chamber 24 is designed for attachment to housing 22 . specifically , the frame 20 is an integral metallic unit having a continuous peripheral primary wall 26 as well as an outermost circumscribing lip 28 and an inboard , inwardly projecting support flange 30 having mounting bores 31 . the flange is designed to fit within an opening 32 ( seen in fig1 ) through wall board 16 between the studs 12 , 14 . in particular , the frame fits within the opening 32 with primary wall 26 engaging the side margin of the opening 32 and adjacent portions of the studs 12 , 14 ; the lip 28 overlies and engages the outer face of wall board 16 . the frame 20 may be secured in place by clamps behind the dry wall and the housing and / or by appropriate threaded fasteners ( not shown ) extending through primary wall 26 and into the studs 12 , 14 . the housing 22 is also of integral metallic construction and includes a pair of spaced sidewalls 34 , 36 , top wall 38 , bottom wall 40 and back wall 42 . as best seen in fig1 , the bottom wall 40 presents an elongated , rectangular slot - like aperture 44 which is bounded by a short lip 46 . finally , the housing has a peripheral flange 48 having bores 50 which mate with the bores 31 of support flange 30 . as illustrated , the housing 22 is designed to fit within frame 20 , with flange 48 abutting support flange 30 . note that the flange 48 is recessed relative to the outer surface of wall board 16 . the air chamber 24 is of open - top , hollow design and includes front and rear walls 52 , 54 , sidewalls 56 , 58 , bottom wall 60 and an uppermost circumscribing lip 62 surrounding and defining an upper opening 64 . the chamber 24 is mounted to housing 22 simply by passing the chamber downwardly through aperture 44 until the lips 46 and 62 interengage . in this fashion , the chamber 24 depends from housing 22 with the hollow interior of the chamber in communication with the interior of housing 22 . importantly , the air chamber extends from the housing to increase the overall air volume of the enclosure without requiring the opening 32 to be enlarged to accommodate the full expanded length of the housing and air chamber . a speaker assembly 18 is next secured to the enclosure 10 . referring to fig3 , a representative assembly 18 includes a baffle 66 with one or more acoustic speakers 68 , 70 mounted on the baffle 66 . the assembly 18 is secured in place by appropriate threaded fasteners ( not shown ) which extend through the margin of the baffle 66 and into selected ones of the mated bores 50 , 31 . this ensures that the assembly 18 is securely mounted to the enclosure 16 . again referring to fig3 , it will be seen that the assembly 18 is recessed relative to the outer surface of wall board 16 . accordingly , a conventional grille may be removably secured in place over the assembly 18 such that the grille is essentially flush with wall board 16 . this gives the entire assembly a neat and finished appearance . the volume of the hollow interior of the air chamber 24 and the volume of the interior of housing 22 is sized in accordance with the operating characteristics of the speaker assembly 18 . in one embodiment , the air chamber has an interior volume of approximately 0 . 2 cubic feet and the housing has an interior volume of approximately 0 . 45 cubic feet for a total volume of 0 . 65 cubic feet ; however , the invention is not limited to these dimensions . it will be appreciated that a number of variations can be made in the enclosure 10 without departing from the spirit and scope of the invention . for example , the frame and housing need to be quadrate , but could be circular or of any other appropriate shape . similarly , the size and shape of the chamber 24 can be varied to suit the needs of the user and the acoustic requirements of the speaker ( s ) to be employed . also , an upper and lower chamber could also be used if desired . finally , the frame 20 , housing 22 , and air chamber 24 may be formed of any suitable materials . the inventors hereby state their intent to rely on the doctrine of equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims .