Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Patent Application No. 61/635,958, filed Apr. 20, 2012, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to muting of musical instruments and, in particular, to attenuating the sound emanating from a harmonica when playing the harmonica. 
     BACKGROUND OF THE INVENTION 
     The harmonica is a popular handheld musical instrument that appeals to a wide range of players from children to seniors, amateurs to professionals. Also called a harp, French harp, blues harp or mouth organ, the harmonica is a free reed wind instrument used primarily in blues and American folk music, jazz, country and rock and roll. 
     One popular form of the harmonica is the ten-hole diatonic harmonica, having two reeds per hole, although there are numerous variations having different numbers of holes, and reeds per hole. As shown for example in  FIG. 1 , the typical construction of a diatonic harmonica  1  includes a pair of reed plates  4 ,  5  attached to opposing faces of a comb  2  defining an air chamber  3  there between. Each reed plate  4 ,  5  contains a set of flexible elastic reeds  7 ,  10  each affixed below rectangular slots  6 ,  9  through which the metallic reeds  7 ,  10  vibrate. The means of attachment of the elastic reeds  7 ,  10  to the reed plate  4 ,  5  may be a rivet, screw, spot weld or any other appropriate attachment means  8 . The elastic reeds may be typically made from a variety of alloys including beryllium copper, phosphor bronze, brass, or stainless steel, although they may also be made from polymeric materials. 
     Harmonicas produce musical tones by a player blowing air into, or drawing air from, a mouthpiece containing multiple holes (or reed chambers) in a manner that causes one or more of the reeds  7 ,  10  therein to vibrate. The reeds  7 ,  10  of each reed chamber are configured such that one reed  7  is preferably played when blowing and the other reed  10  when drawing. Surrounding the reeds  7 ,  10  is an enclosure typically comprised of a pair of cover plates  11 ,  12  fashioned from metal, plastic, or wood, and providing an opening  15  to the atmosphere, usually positioned on the face of the harmonica opposite the player&#39;s mouth, downwind of the air flow. 
     In a non-limiting example of the operation of the harmonica, the player blows into the air chamber  3  causing the blow reed  7  to close, obstructing the reed slot  6 , thereby interrupting the flow of air  14 . This flow interruption causes intermittent compression and rarefaction of the air, creating acoustic sound that exits the opening  15  provided by the cover plates  11 ,  12  which transmit an acoustic pressure to the surrounding air, whereupon it may be perceived by the ear of a person within proximity to the instrument. 
     When practicing or playing for personal pleasure, however, it may be desirable to prevent the sound from being perceived by persons other than the player so as not to disturb others or to bring unwanted attention to the player. 
     Further, it may be undesirable or disadvantageous for the player to simply play less forcefully, as a certain minimum air flow is necessary for the instrument to operate property. 
     A need exists, therefore, for a way to attenuate the loudness of a harmonica so as to permit playing or practicing the instrument without disturbing others. 
     SUMMARY OF THE INVENTION 
     The present invention fulfills this need by providing methods and devices for attenuating sound produced when playing a harmonica. 
     In one aspect of the present invention, there is provided a method for attenuating sound of a harmonica, comprised of providing a sound blocking and reflecting means and, optionally, providing a sound absorbing means. 
     In one embodiment, the sound blocking and reflecting means includes upper and lower enclosures which surround reed plates of a harmonica, wherein the enclosures provide a physical barrier to egress of acoustic pressure, and thus attenuates the sound emanating from the harmonica. A sound-absorbing material is provided on interior surfaces of the enclosures. 
     In another embodiment, the sound and reflecting means includes a tubular portion that protrudes into the upper and lower enclosures of a harmonica, wherein the tubular portion cooperates with the volume of air within the enclosures to create a Helmholtz resonator. 
     In another embodiment, the sound and reflecting means includes a tubular structure that communicates with the air chamber within the comb of a harmonica, thereby providing a quarter wavelength reflecting means. The length of the tubular structure is adjustable by way of nested tubular sections slideably attached internal or external to one another. 
     In another aspect of the present invention, there is provided a device for attenuating sound produced from a harmonica, comprised of a sound blocking and reflecting means and, optionally, a sound absorbing means. 
     In one embodiment, the sound and reflecting means includes baffles or anechoic chambers which cause reflections or destructive interference of acoustic waves. 
     In another embodiment, the sound and reflecting means includes a secondary enclosure that forms an anechoic chamber external to a first enclosure of a harmonica. The secondary enclosure is attachable to the first enclosure by way of fastening means such as, without limitation, permanent magnets. An air channel or orifice is provided in the secondary enclosure to allow egress of air sufficient to sustain vibration of the reeds of the harmonica. Said air channel or orifice may be positioned at the rear or the side of the secondary enclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full understanding of the present invention can be gained from the following detailed description of non-limiting embodiments when read in conjunction with the accompanying drawings in which: 
         FIG. 1  is cross sectional view of a prior art diatonic harmonica; 
         FIG. 2  provides a cross sectional view of a harmonica in accordance with the methods of the invention having an enclosure, sound absorbing material, perforated barrier, and restricted air channel; 
         FIG. 3  provides a harmonica in accordance with the methods of the invention having an enclosure with air channels protruding therein; 
         FIG. 4  provides a harmonica in accordance with the methods of the invention having at least one tubular section in communication with the air cavity of the comb of a harmonica. 
         FIG. 5  provides a device in accordance with the invention having baffles within an enclosure that partition air space that interrupt transmission of acoustic waves, yet permit the flow of air; 
         FIG. 6  provides a top view of a device in accordance with the invention that provides a secondary enclosure containing baffles that is attached to the primary enclosure of a harmonica, in which air exits the rear; and 
         FIG. 7  provides a top view of a device in accordance with the invention that provides a secondary enclosure containing baffles that is attached to the primary enclosure of a harmonica, in which air exits the side. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A complete understanding of the present invention will be obtained from the following detailed description taken in connection with the accompanying drawing figures, wherein like reference characters identify like parts throughout. 
     Referring now to the drawings, one embodiment of the present invention, as shown in  FIG. 2 , includes a method for attenuating sound of a harmonica by providing a sound blocking and reflecting means and a sound absorbing means comprised of a comb  2  upon which are fastened reed plates  4 ,  5  containing flexible reeds  7 ,  10 , providing an upper enclosure  20  having an exterior surface and interior surface, which creates an air chamber  25 , and providing sound absorbing material  26  disposed on the interior surface. A perforated barrier  24  may be provided that divides the air chamber into a first chamber  25  and a second chamber  26  which permits transmission of a portion of the acoustic energy  28  from the first air chamber to the second air chamber, wherein reflections further contain and dissipate acoustic energy. 
     The upper enclosure also includes a rear panel  21  having a portion  21 A aligned substantially parallel to the reed plates  4 , which in cooperation with the reed plate  4 , comprises a transmission channel  23 . The combination of the transmission channel  23  and the air chamber  25  comprises a Helmholtz resonator which may further attenuate the egress of acoustic energy by way of destructive interference, while permitting flow of air necessary for sustained oscillation of the reeds  7 ,  10 . In this embodiment, and all subsequent embodiments disclosed herein, the present invention also includes a lower enclosure  29  which is substantially a mirror image of the upper enclosure  20  and which contains the same elements therein as the upper enclosure. 
     Suitable sound absorbing means for use according to the embodiments of the present invention include, without limitation, open-cell foams such as polyamide foam, wool, or viscoelastic damping material or any other suitable sound absorbing means used by those skilled in the acoustic arts. 
     In this embodiment, and all subsequent embodiments disclosed herein, the enclosure may be fabricated of a material of suitable mass or density, such as metal alloy, high molecular weight polymer, or ceramic to restrict vibration, hence transmission of sound waves. 
     Another embodiment of the present invention, as shown in  FIG. 3 , includes a method for attenuating sound of a harmonica by providing a sound blocking and reflecting means comprised of an upper enclosure  30 , which creates an air chamber  32 , that cooperates with a rear panel  35  having portions  30 A,  35 A aligned substantially parallel to the reed plate  4  which cooperate to comprise a transmission channel  36 . The combination of the transmission channel  36  and the air chamber  32  comprises a Helmholtz resonator in a manner similar to the embodiment described in  FIG. 2 . The transmission channel may be a rectangular slot or a tubular structure. 
     Another embodiment of the present invention, as shown in  FIG. 4 , includes a method for attenuating sound of a harmonica by providing a sound blocking and reflecting means comprised of at least one tubular structure  41  comprised of a first tubular section in communication with an air cavity  3  between the reed plates  4 ,  5 . The first tubular section penetrates through the comb  2 , providing a quarter-wavelength reflecting means. The length of the tubular structure may be adjustable by way of an independent nested second tubular section  42  telescopically attached internal or external to the first tubular section  41 . The second tubular section  42  may be provided with orifice  44  to permit passage of air. 
     Another embodiment of the present invention, as shown in  FIG. 5 , provides a device for attenuating sound of a harmonica that includes a sound blocking and reflecting means. The sound blocking and reflecting means of the device is comprised of an enclosure  50 , which is attached to cover plates  11 ,  12  of the harmonica which may be substantially bowl-shaped, wherein baffles such as  53 ,  54 ,  56  are disposed which deflect air flow  60  and interrupt projection of acoustic waves. The device includes a bulkhead plate  51  through which are disposed through-holes  52  to permit passage of air into the cover  50 . A gap  57  is provided around the periphery of the cover  50  to permit air  60  to escape therefrom. The gap  57  preferably is directed forward so as to direct the escaping sound to be most effectively perceived by the player. The device is attached to a harmonica by permanent magnets  59  or any suitable attachment means, such as hook-loop fabric, double sided tape, screws, or the like. 
     Another embodiment of the present invention, as shown in  FIG. 6 , provides a device for attenuating sound of a harmonica that includes a sound blocking and reflecting means. The sound blocking and reflecting means of the device is comprised of a secondary enclosure  60  that is attachable to the harmonica  1 . Disposed within the secondary enclosure  60  are one or more perforated panels, such as  62  and/or baffles, such as  64  and  65 , which reflect, interrupt, and/or deflect transmission of acoustic energy. An orifice or passage  69  is provided at the rear of enclosure  60  to permit sufficient egress of air so as to sustain vibration of reeds  7  and/or  10 . The device is attached to a harmonica  1  by an adhesive elastomeric tape  61  which provides an air-tight seal with the primary enclosures  20 ,  29  of the harmonica. It can be appreciated by those skilled in the art that alternative attachment means may be provided by hook-loop fabric, magnets, adhesives, screws, or the like. 
     Another embodiment of the present invention, as shown in  FIG. 7 , provides a device for attenuating sound of a harmonica that is similar to the embodiment of  FIG. 6 , but having an orifice  79  at the side so as to direct acoustic energy and air flow laterally. The sound blocking and reflecting means of the device is comprised of a secondary enclosure  70  that is attachable to the harmonica  1 . Disposed within the secondary enclosure  70  are one or more perforated panels, such as  72  and/or baffles, such as  73 ,  74  and  75 , which reflect, interrupt, and/or deflect transmission of acoustic energy. 
     Although the preceding aspects of the invention are described herein with respect to a single pair of reeds, it shall be understood that they may be applied to multiple or all reeds of a harmonica. 
     It shall be further understood that different aspects of the invention can be implemented individually, collectively or in combination with each other. 
     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications that are within the spirit and scope of the invention, as defined by the appended claims.

Technology Category: 3