Abstract:
A muter configured to be placed beneath the soundboard of a piano (in the case of a grand piano) in order to attenuate the downward transmission of sound. The muter employs blocks of acoustic foam, shaped to frictionally engage the structural elements of the piano in order to retain the muter within the piano. The muter is easily installed and removed. A version configured for use with an upright piano is also disclosed.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
         [0001]    Not Applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         MICROFICHE APPENDIX  
         [0003]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    1. Field of the Invention  
           [0005]    This invention relates to the field of musical instruments. More specifically, the invention comprises a muter capable of diminishing the sound emitted by a piano.  
           [0006]    2. Description of the Related Art  
           [0007]    [0007]FIG. 1 illustrates a piano  10 . It fundamentally consists of keyboard assembly  20 , frame  12 , and lid  14 . Those skilled in the art will know that keyboard assembly  20  contains keys, along with attached hammer mechanisms configured to strike the strings when the user strikes a particular key. A large number of strings extend away from keyboard assembly  20  in a generally perpendicular direction, with the strings lying approximately in a single plane. The far end of each string is anchored, directly or indirectly, to frame  12 .  
           [0008]    All pianos are, of course, designed to produce tones covering a large bandwidth. This fact requires the use of strings having different lengths. Thus, the treble section of the keyboard (to the right in the view as shown) employs strings of shorter length than the mid section. This fact explains the curved shape of frame  12 . The structure of a concert piano is therefore quite complex, in that it must encompass several curves.  
           [0009]    Those skilled in the art will also know that pianos include a soundboard to amplify the sound produced by each vibrating string. This soundboard is typically a large flat panel, suspended beneath the strings. It is suspended in such a fashion as to minimize damping of any vibration induced by the moving strings. The soundboard is largely responsible for the rich tonal texture produced in a well-made piano. It substantially augments resonance. It also produces certain harmonic frequencies, owing to the tendency of the unified sound board to flex according to its own natural frequencies. Finally, the soundboard also tends to provide enhanced blending of different frequencies to produce beat frequencies.  
           [0010]    If the operator strikes a first key in the bass range and a second key in the treble range, these two string sets are located remotely from each other (30 to 40 inches apart, typically). Although the human ear may perceive a beat frequency, the two strings are generally too far apart to produce sympathetic vibrations in each other. Because both sets are close to the soundboard, however, the soundboard can transmit the two frequencies and produce the desired sympathetic vibrations.  
           [0011]    Lid  14  is hinged to frame  12 . It is contoured to cover the open top of frame  12 . The strings lie beneath lid  14  with the soundboard, in turn, lying beneath the strings. The hinge is typically placed on the left side of frame  12  in the view as shown. With lid  14  closed, some of the sound produced by piano  10  is trapped within. In a concert setting lid  14  would be propped open, in order to project sound out toward the audience. Thus, the reader will appreciate that lid  14  does provide some selective muffling of piano  10 .  
           [0012]    [0012]FIG. 2 shows a view of piano  10  from underneath. Piano strings are typically made of steel. They cumulatively place several thousand pounds of compression on frame  12 . It is therefore necessary to strengthen frame  12 . Anchor structure  22  is attached to keyboard assembly  20 . A series of beams  24  extend radially forward from anchor structure  22 , terminating in intersections with frame  12 . End plate  28  stiffens the leading portion of frame  12 , and serves to anchor one of the three legs  16 . Numerous other structures, such as pedal assembly  18 , are present. These other structures are unimportant to the present invention.  
           [0013]    Soundboard  26  lies above beams  24 . It is important to realize that there is a significant gap between the tops of beams  24  and soundboard  26 . Again, soundboard  26  must be free to oscillate undamped.  
           [0014]    Looking at FIG. 2, those skilled in the art will realize that soundboard  26  projects sound downward as well as upward. The closing of lid  14  does nothing to attenuate this downward transmission.  
         BRIEF SUMMARY OF THE INVENTION  
         [0015]    The present invention comprises a muter configured to be placed beneath the soundboard of a piano (in the case of a grand piano) in order to attenuate the downward transmission of sound. The muter employs blocks of acoustic foam, shaped to frictionally engage the structural elements of the piano in order to retain the muter within the piano. The muter is easily installed and removed. A version configured for use with an upright piano is also disclosed. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a perspective view, showing a concert piano.  
         [0017]    [0017]FIG. 2 is a perspective view, showing a concert piano.  
         [0018]    [0018]FIG. 3 is a perspective view, showing the proposed invention.  
         [0019]    [0019]FIG. 4 is a perspective view, showing the proposed invention being installed in a concert piano.  
         [0020]    [0020]FIG. 5 is a perspective view, showing the proposed invention installed in a concert piano.  
         [0021]    [0021]FIG. 6 is a perspective view, showing details of the proposed invention.  
         [0022]    [0022]FIG. 7 is an isometric view, showing details of the proposed invention.  
         [0023]    [0023]FIG. 8 is an isometric view, showing details of the proposed invention.  
         [0024]    [0024]FIG. 9 is a perspective view, showing an alternate method of installing the proposed invention.  
         [0025]    [0025]FIG. 10 is a perspective view, showing a frequency-modified version of the proposed invention.  
         [0026]    [0026]FIG. 11 is a perspective view, showing a version of the proposed invention configured to fit an upright piano. 
     
    
     REFERNECE NUMERALS IN THE DRAWINGS  
       [0027]    [0027]                                                     REFERENCE NUMERALS IN THE DRAWING                                    10   piano   12   frame           14   lid   16   leg           18   pedal assembly   20   keyboard assembly           22   anchor structure   24   beam           26   soundboard   28   end plate           30   piano muter   32   acoustic foam block           34   sheet   36   beam channel           38   VELCRO panel   40   acoustic foam           42   NYLON shell   44   VELCRO panel           46   profile modified block   48   beam gap                        
       DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    [0028]FIG. 3 shows an overall view of piano muter  30 . The combined structure shown is a sound dampening element configured for installation next to a piano soundboard, on the side away from the piano strings. It consists essentially of an approximately planar sheet  34  attached to a group of acoustic foam blocks  32 . Beam channels  36  lie between adjacent acoustic foam blocks  32 .  
         [0029]    Returning briefly to FIG. 2, the reader will observe that numerous beam gaps  48  lie between beams  24 . When piano muter  30  is installed, acoustic foam blocks  32  fit snugly within beam gaps  48 . Stated conversely, beams  24  fit snugly within beam channels  36  on piano muter  30 .  
         [0030]    [0030]FIG. 4 shows piano muter  30  placed below piano  10 , in preparation for installation. Sheet  34  is preferably made of flexible material so that the user can lift individual portions and push them up into place, without having to lift the entire device simultaneously. Acoustic foam blocks  32  are compressible and resilient. They are preferably made larger than beam gaps  48  so that they must be compressed in order to fit within beam gaps  48 . This compression introduces frictional engagement between beams  26  and acoustic foam blocks  32 , which serves to retain the device in the installed position.  
         [0031]    [0031]FIG. 5 shows piano muter  30  properly installed. The reader will observe that sheet  34  is flush with the bottom of piano  10 . The presence of acoustic foam blocks  32  within beam gaps  48  attenuates the sound emitted from the bottom of piano  10 .  
         [0032]    In configuring the thickness of acoustic foam blocks  32 , it is important to decide whether they should touch soundboard  26  when installed. If a gap between soundboard  26  and acoustic foam blocks  32  remains when piano muter  30  is installed, then the resonance and other tonal characteristics of the piano will not be significantly altered. Rather, only the volume will be attenuated. If, on the other hand, acoustic foam blocks  32  actually touch soundboard  26 , mechanical damping of soundboard  26  will alter the character of the sound produced (rather than simply diminishing it).  
         [0033]    Returning to FIG. 3, those skilled in the art will realize that sheet  34  is useful for determining the installed position of acoustic foam blocks  32 . If sheet  34  is made to rest flush against the bottom of frame  12  (or some other feature), then a firm reference is established for the installed position of acoustic from blocks  32 . One need only then determine the appropriate thickness for the blocks.  
         [0034]    It is possible to implement the invention as simply a set of shaped acoustic foam blocks  32 , which would be shoved into place without the use of sheet  34 . However, given the preceding explanation of the importance of producing or avoiding soundboard contact, the reader will appreciate the advantages represented by sheet  34 .  
         [0035]    The material used for acoustic foam blocks  32  can be virtually any type of sound absorbing material, with soft foam being particularly effective. It is desirable to make these blocks detachable from sheet  34 , in order to facilitate installation, transportation, and the replacement of damaged blocks. FIG. 6 shows sheet  34  with a set of acoustic foam blocks  32  detached. Sheet  34  has a set of VELCRO panels  38 , arranged in appropriate shapes.  
         [0036]    It is very difficult to adhesively attach materials to foam. FIG. 7 shows one solution to this problem: Each acoustic foam block  32  is made of a piece of acoustic foam  40 , surrounded on several sides by NYLON shell  42  (many other types of fabric or mesh could be used). NYLON shell  42  is sewn to acoustic foam  40 , or attached by other conventional means.  
         [0037]    [0037]FIG. 8 shows the bottom of NYLON shell  42 , which is covered by VELCRO panel  44 . Referring to FIGS. 6, 7, and  8 , the reader will appreciate that each assembled acoustic foam block  32  can be placed on sheet  34  by mating the appropriate VELCRO panel  44  to the appropriate VELCRO panel  38 . The outline of VELCRO panels  38  visually guide the use in appropriately placing the various acoustic foam blocks  32 . Of course, the entire upper surface of sheet  34  could be covered in VELCRO. Visual guidance could then be provided by simply printing the outlines of the acoustic foam blocks on the upper surface. Alternatively, as little securing force is needed, smaller VELCRO patches could be used.  
         [0038]    The use of detachable acoustic foam blocks  32  also provides an alternate method of installation. Some users may wish to push each acoustic foam block  32  mostly into position beneath piano  10 , then attach sheet  34  and push the blocks up to their seated position. FIG. 9 graphically depicts this alternate approach.  
         [0039]    The frictional engagement between acoustic foam blocks  32  and beams  24  is sufficient to retain the device in place, as well as supporting the attached weight of sheet  34 . However, those skilled in the art will appreciate that many different methods of attaching the device could be used. As one example, sheet  34  could be attached directly to piano  10  using mechanical fasteners such as screws, clips, or VELCRO. In that variant, the frictional engagement between acoustic foam blocks  32  and beams  24  would be unimportant.  
         [0040]    The configuration of acoustic foam blocks  32  in FIG. 3 provides approximately uniform sound attenuation across the frequency range of the piano. However, it is possible to selectively vary the attenuation according to frequency. Persons listening to piano music often perceive notes lying within the mid range to be softer than notes within the bass and treble extremes. This is true for both objective and subjective reasons. Objectively, it is well known that higher pitches tend to be more readily perceptible over background noise. Subjectively, because the notes within a piano&#39;s mid range are most frequently played, they tend to lose some novelty and therefore be less readily perceived. Accordingly, it may be desirable to alter piano muter  30  in order to attenuate certain frequencies more than others.  
         [0041]    [0041]FIG. 10 shows piano muter  30  with profile modified blocks  46 . Those blocks lying beneath the piano&#39;s mid range are thinner than those lying beneath the bass and treble sections. The result is that the mid range is attenuated less than the bass and treble sections, resulting in a more balanced tone to the listener. Of course, many different effects are possible by altering the profile ofthe blocks. One could just as easily attenuate the bass and treble sections to produce a subjective “boost” in the mid range. In general, the foam blocks should be thicker in the bass section in order to achieve a balanced attenuation.  
         [0042]    Those skilled in the art will realize that pianos come in many differently sizes and shapes. The figures presented thus far have been particular to a grand of piano. Even within this type, many variations must be accommodated. As an example, some such pianos have only three beams. Obviously, the particular shape of piano muter  30  can be altered to fit any of these variations.  
         [0043]    Some pianos also employ radically different structure. FIG. 11 depicts upright piano  48 . This type of instrument still employs strings and a soundboard. Both the strings and the soundboard are oriented vertically, however. Beams  24  are located in the rear of the piano, just behind soundboard  26 . A modified version of piano muter  30  is shown. Like the previous embodiments, it also has sheet  34  and acoustic foam blocks  32 . It is installed in the rear of the instrument, however, rather than the bottom. This alternate embodiment serves to illustrate the fact that piano muter  30  can be altered for use with virtually any type of piano.  
         [0044]    The use of separate foam blocks  32  is advantageous in that they securely obstruct the spaces between beams  24 . Those skilled in the art will realize, however, that piano muter  30  could also be made as a single piece of foam. The foam itself would then be cut to fit the outline of the piano and secured in place using mechanical fasteners.  
         [0045]    Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiment of the invention. Thus, the scope of the invention should be fixed by the following claims, rather than by the examples given.