A quick release mute for a stringed instrument

Abstract

A mute for a stringed instrument which has a bridge, such as a violin, comprising at least two plates 10A, 10B arranged in use either side of a bridge 250. The plates are coupled at two separate locat

Description

The present invention relates to a mute for a stringed instrument that is played using a bow, such as a violin or viola. More particularly, but not exclusively, the mute is fitted beneath strings of the stringed instrument. Background Most known mutes for stringed instruments, produce one deliberate modification of the sound vibration spectrum that travels through the bridge of the instrument. Each individual design of mute produces its own single static modification. This is usually achieved by placing a mass on top of the bridge which provides a compressive force, to either one vertical grip with one or several ‘arms’ on the rear face of the bridge, or two vertical grips with one or more arms each, on both the front and back faces of the bridge. Some types of mutes have an additional spring mechanism to increase the compressive force, which tends to be a constant force once applied, rather than a variable force. One type of mute is applied by placing it on the strings of the musical instrument, in a neutral position, and then sliding forwards to make contact with the bridge during play. This type of mute always has an element which is positioned on top of the bridge during operation. The element serves to stabilise the mute physically whilst applying its own compressive force to the bridge. Mutes exist to enable musicians to reduce the projection of sound from instruments by modifying, or dampening, vibrations, in order that less sound energy is projected from the instrument. This can also be helpful in reducing any disturbance to arbitrary listeners during rehearsals or when practising, so as to avoid disturbing neighbours. This type of mute achieves its effect by enhanced mass or compression or both. However, each type of mute produces its own single, static effect and this can limit normal function and operation of a stringed instrument when being played which can be detrimental, for example when practising. Furthermore, the size and positioning of mutes can also inhibit full use of the bow by a player, because there can for example, be direct physical contact with the players thumb knuckle during performance. The present invention overcomes these problems. Another aim of the invention is to provide a system which is used with a mute which helps a player to measure and monitor their performance. A yet further aim of the invention is to provide a mute which can be attached and removed quickly and thereby assist a player to deploy the mute when required; and likewise remove the mute quickly after it is needed in a performance. Prior Art A traditional practice mute is a device that rests on a bridge and over the strings of a stringed instrument such as the one that is sold by Gewa Practice Mute, details of which are at https: / / www.stringersmusic.com / products / gewa-practice-mute?variant=40099718070319¤cy=GBP&utm medium=product sync&u tm source=google&utm content=sag orqanic&utm campaiqn=saq organic. Another example of a mute is described in United States patent US 5 510 67A (WEGMANN) which discloses a mute for stringed instruments that has a clamp arranged around the bridge. International patent application WO 85 / 01376A1 (GOLDNER RICHARD) discloses an improved mute for stringed instruments that is placed over and onto a bridge. Japanese patent application JP 2006285078A (HARADA MINEO) discloses a mute for a stringed instrument that is placed over and secured onto a bridge. Summary of the Invention According to a first aspect of the present invention there is provided a mute for a stringed instrument which has a bridge, the mute comprises at least two plates; each plate being arranged in use either side of the bridge, wherein the at least two plates are connected one to another at two separate positions by an adjustable attachment means which enables adjustment of the separation between the plates and adjustment of a compressive force which the at least two plates apply to the bridge wherein at least one of the adjustable attachment means includes a quick release device. In some embodiments at least two of the plates each has a hole or an aperture for receiving the adjustable attachment means. An advantage of the quick release device is that it enables the mute to be fitted and removed quickly. In some embodiments the mute has two quick release devices which connect the at least two plates one to another so that they can apply pressure to the bridge. In some embodiments at least one of the plates has at least one slot along which the adjustable attachment means is able to slide. An advantage of this is that a user is able to fit the mute quickly and easily to the bridge which may be important for example during a live performance. In a particularly preferred embodiment at least one of the quick release devices connects the at least two plates one to another at the first position, through holes or apertures formed in two of the plates; and at least a first plate has a slot formed in it, and at least a second plate has another hole or aperture formed for receiving a second quick release device. One end of the second quick release device passes through the hole or aperture and the other ends slides into the slot so that the at least two plates can be connected one to another at the second position using one quick release device. It is also appreciated that in another embodiment two quick release devices may be used. Preferably the at least first plate has two slots for slidably receiving one end of each of two quick release devices and the second plate has two holes through which the separate quick release devices pass. An embodiment is also envisaged in which two quick release devices are used and each plate has a hole or aperture and a slot for receiving the two quick release devices. Optionally a circlip or nut or other retainer may be provided to connect and retain the, or each, quick release device with respect to the plate to which it is attached. Quick release devices may be coloured for example to enable a particular selection of one or two pre-set quick release devices to be connected quickly to the bridge when required. A marker or indicator may be provided for this purpose. Another advantage of the mute, when fitted with one or more quick release device, is that a specific compression force can effectively be ‘pre-set’ for each quick release device for rapid deployment and removal. In some embodiment the quick release devices and this, when rotated on a boss whilst positioned on the plate or prior to being connected to a plate. In some embodiments at least one plate has a recess for receiving an end of the, or each, adjustable attachment means or quick release device. The quick release connectors comprise a shaft with a boss attached thereto and a lever which may be on a cam on an angle. Typically, the quick release lever comprises a shaft or skewer rod connecting a boss with a swivel lever which has a cam or other similar means, and the cam has an over-centre lock which when deployed locks the mute in place to apply a specific compression force to the two plates. The quick release device is able to apply pressure in two or more (probably three) small increments whilst, at the same time, being adjustable to produce a baseline pressure which is adjustable by a user to suit the thickness of any violin bridge. In some embodiments at least an inner face of each plate is shaped to correspond to the profile of the bridge. In some embodiments at least one layer of resiliently deformable material is in use located between at least one the of the two plates and the bridge in order to vary the compressive force and to tune the effectiveness of the mute. In some embodiments, each inner face, of the at least two plates, has a resiliently deformable layer that is in contact engages with opposite faces of the bridge. In some embodiments at least one layer of resiliently deformable material has raised regions and lowered regions on its surface which is in contact for engaging with the bridge. In this way the mute can be positioned directly against the bridge and entirely beneath the strings so that the musician playing the instrument is not inhibited by the mute during playing. Fitting a mute in this manner also has the advantage of removing visual detractions and physical barriers to the player’s technique that were often caused by traditional mutes that sit over the strings and the bridge of a stringed instrument and which have impeded movement of the bow along the entire playing length of the strings. In a preferred embodiment, the mute is constructed of at least two separate plates of a substantially rigid material that are located either side of the bridge. For example, one or both plates may be formed from wood, a synthetic plastics material or carbon fibre. It is appreciated that in some embodiments two or more plates may be provided on one, or both sides, of the bridge to enable a user to selectively adjust the muting effect of the mute. The shape, mass, density and dimensions of each plate may be varied for different stringed instruments and / or to achieve different tonal ranges. It is therefore appreciated that in some embodiments, both plates may be identical, and in other embodiments the shape and / or mass and / or density and / or dimensions of each plate may be different. In some embodiments one or both plates may be interchangeable so that a user can select plates to change the tonal ranges of the string instrument for different situations, such as different locations, or for different listeners. Optionally a set of different plates may be supplied so as to enable a user to pack the plates in such a way as to achieve a desired results for a particular instrument. Typically, the bridge has a convex front face and a planar rear face and therefore pressure between the plates can optionally be applied at different positions and / or with different magnitudes of force across the plates depending upon the shaping of the inner surfaces of the plates that interface the bridge. Advantageously the surface profile of the plates can be configured to provide a plurality of compression configurations which alter the manner and force of compression applied across the bridge when the adjustable attachment means is / are adjusted. Additionally, the position of the mute on the bridge can be changed to further increase the various compression configurations. For example, positioning the mute in different horizontal positions on the bridge or different vertical positions of the bridge will each create different points of compression which will each alter the muting effect by changing the tonal spectrum received by the listener. In a preferred embodiment at least an inner face of each plate is shaped to correspond to the profile of the bridge. In this way the plate can fit closely across the bridge which traditionally has a contoured profile so that a large surface area of the plate is in direct contact with the bridge. It is appreciated that the outer face of the plate may match the shape of the inner face or may have a different profile. For example, the outer face of one or both plates may have a flat surface. For example, in a preferred embodiment the plates are each shaped to present inner surfaces that are closely configured to the shape of the bridge itself or shaped to exactly match the profile of the bridge. This shaping means that the plates are evenly spaced from the bridge across the adjoining region, and this therefore produces the most effective control over the tonal range and most accurate adjustment. In another embodiment at least part of an inner face of at least one plate is substantially planer so that it does not exactly match the profile of a traditional bridge. In this way regions of the plate are spaced apart from the bridge whilst other regions of the plate are in contact with the plate, thereby providing further compression profiles that may be applied to generate different tonal ranges. In yet further embodiments at least an inner face of each plate may be shaped to include a raised portion to create a region of increased compression against the bridge to achieve a desired tonal range. It is appreciated that the mute plates may be designed and made to correspond to a specific stringed instrument. For example, the shaping of the stringed instrument may be measured, or imaged and bespoke plates made, such as being three dimensionally printed from an image to match the stringed instrument. In some embodiments the mute may be provided with plates of different thicknesses which can change the level of compression that can be applied and may also alter sound emitted due to thickness and the different range of compression that can be applied. For example, in some embodiments a first plate may be of a first thickness and a second plate may be of a second thickness, or a slim mute may be provided with two narrow plates and a wide mute may be provided with two wide plates. In some embodiments the thickness of a plate may vary across the length of the plate. For example, the lateral edges of the plate through which attachment means may pass or be secured, may be thicker than the regions of the plates that contact the bridge to provide increased strength where the adjustable attachment means is / are fitted and adjusted. In yet further embodiments the plates may be formed of two or more layers of material. This may help to alter the acoustic properties of the plates as well as providing alternative manufacturing options. For example, in some embodiments the plates may be formed from layers of different materials, such as layers of wood, or layers of wood interspaced with layers of a resiliently deformable material, such as rubber layer, or flexible adhesive between two layers of wood. In preferred embodiments the mute includes at least one layer of resiliently deformable material provided between the two opposing plates that abut the bridge in use. Preferably at least one of the inner faces of the plate(s) has a resiliently deformable layer that contacts the bridge and acts to reduce transmission of sound generated by the stringed instrument, as well as providing a compressible layer between the two or more plates. Furthermore, the resiliently deformable layer may serve to reduce damage to the bridge. In preferred embodiments both plates have a resiliently deformable layer on an inner surface so that the resiliently deformable layers of both plates contact the bridge. The plates are connected by at least two adjustable attachment means so that the plates are joined together to fix the location of the mute on the bridge. Additionally, as the adjustable attachment means are adjusted, the distance between the plates and in particular the compression of the resiliently deformable layer can be adjusted. This enables the mute to be fixed in various different positions on the bridge and allows for variable compression between the plates which is manually controlled by a user to provide numerous compression configurations. It is also appreciated that where two quick release adjustable devices are used one may be set to provide a different amount of compression compared with the other, thereby enabling the user to apply different compressive forces to the bridge in different locations. Optionally quick release devices may be the same size, but they may be different sizes so as to enable for example access to an inner part of the bridge and an outer part. Different colours may also be applied to different types of quick release device. For example, one quick release device is made from tungsten and another from a lighter material such as a synthetic plastics material. In this way they impart different properties to the mute which affect the resonance or tone of the stringed instrument. In such embodiments the tungsten quick release device is significantly heavier than the one made form a synthetic plastics material and one way in which these can be distinguished quickly is to supply then in or mark them with different colours and / or different textures or coatings, which also helps to select them in low light levels. Advantageously as each attachment means is adjustable, each can be independently altered to control the application of the oppositional compression created by the plates and thereby the degree of compression at focused locations. The location of focus points of compression on the bridge and the degree of compression at each focus points alters the tonal range emitted by the stringed instrument. Because of the complex spectrum of overlapping acoustic vibration within the bridge, which is driven by strings of the string instrument, the application of pressure adjustments in different positions of the mute across the bridge will affect the harmonic range received by the listener, via their eardrum, in numerous different ways. As all animal hearing is individual in its potential reception of sound frequencies and also because this sense changes with age, the mute of the present invention is also particularly beneficial to operators with any form of hearing impairment or other preference, by adjusting the relative intensity of particular elements of the tonal spectrum to suit a user or listener’s requirements. In preferred embodiments the resiliently deformable layer extends across the full surface of an inner face of the plate. The resiliently deformable layer may be formed from a material such as rubber or silicone, or a cellular structured material such as foam. The resiliently deformable layer acts to dampen sounds and also protects the bridge from damage when compressed between the plates. In some embodiments the resiliently deformable material has a raised and lowered surface for engaging with the bridge. Advantageously this increase ease of compression, helping to facilitate finer adjustment and also reducing the amount of material required and thereby reducing the weight of the mute. In yet further embodiments the resiliently deformable layer may be formed from an array of separate patches arranged across the surface of one or both plates. The aforementioned features enable further different compression configurations to be provided. In some embodiments the thickness of the resiliently deformable layer may be variable across the surface of each plate. For example, the mute may have plates with planar inner surfaces that have a resiliently deformable layer that is shaped to the profile of the bridge. In this way the plates can be manufactured as standard parts, and the mute can be specifically fitted by the shaping of the resiliently deformable layer. In preferred embodiments the at least two plates each have corresponding apertures and / or a recessed region for receiving the adjustable attachment means. In this way an attachment means is received through the corresponding aperture(s) and / or guided into the recess(es) and secured to join the plates. In some embodiments the plates may include connectors for receiving the adjustable attachment means, such as a threaded collar that accepts a threaded shank, or a ratchet mechanism. Preferably the apertures, recesses and / or connectors are arranged to be in a part of each plate that extends beyond the width of the bridge so that no adaption of the bridge is required to accommodate the adjustable attachment means and so that the adjustable attachment means can be easily accessed either side of the strings. It is appreciated that in some embodiments a bridge may include apertures through which the adjustable attachment means may pass. Preferably the adjustable attachment means is a form of threaded bolt with at least one adjustment nut to enable simple fine adjustment. For example, in preferred embodiments the adjustment means comprises a head connected to a threaded shank that receives an adjustable nut that can be tightened and loosened along the shank by turning the nut clockwise and anticlockwise. An example of a quick release adjustment mechanism is one which includes a lever or ratchet with a cam connected to a rotating head or boss by way of a shaft. The shaft may have an entire threaded length or threaded portions at it ends to which a lock nut and the adjustment mechanism is connected thereby enabling a distance between the quick release mechanism and the lock nut to be varied. This in turn enable the compressive force to be varied. Preferably the adjustable nut is located adjacent the bridge. This provides access to a user and does not interfere with hand or bow movement during playing. In some embodiments an attachment means is provided on both faces of the mute so that adjustment of the adjustable attachment means may be permitted on both sides of the bridge when fitted. This provides dual adjustment that enables finer adjustment of the compression and may enhance ease of use for some players who may find it easier to adjust the mute from one side than the other. In some embodiments the adjustable attachment means is a knob with right-handed and left-handed threads. These enable the adjustable attachment means to be adjusted from either side of the mute by rotating each knob in the same direction to tighten the bridge and the same direction to loosen the bridge. By rotating each of the adjustable attachment means in opposite directions, a user is able to tighten the mute; and by correspondingly rotating each of the adjustable attachment means, in reverse directions, the user is able to loosen the mute. This is of particular benefit as the mute is fitted below the strings and access to the adjustable attachment means is restricted. Consequently, it has been found to be less fiddly and so easier and quicker to adjust the mute, with the right-handed and left-handed threads. This is especially important during a live performance. In preferred embodiments each plate has a substantially flat lower edge and a substantially curved upper edge in order to match the shape between the surface of the stringed instrument and the strings. For example, the plate may be substantially hemispherical. In some embodiments a lower edge of the plates may be shaped to correspond to the profile of the stringed instrument, for example the lower edge may be curved. In some embodiments a lower edge of each plate may be shaped to mirror the upper edge of the plate, so that both edges have the same shaping to enhance the aesthetic appearance of the mute and making it less obvious when fitted. For example, both the lower edge and upper edge of the plate may have the same profile of the stringed instrument. In some embodiments the plates of the mute may be available in different weights so as to alter the muting effect, whereby increased mass may increase the muting effect. For example, the plates may be thicker to increase mass, or the plates may be formed from materials with a greater density to alter mass, or the plates may include portions of material with a greater mass to alter mass of the plate, or a combination of any of the before mentioned mass altering options may be used to change the mass of each plate. It is also appreciated that the size, mass and shape of the material or various materials from which the plates are formed may be varied to have different muting effects. Different materials have different propensities to dampen sound, for example due to material structure and / or density, and therefore different materials may be chosen to form a plate to enable a user to select the preferred muting effect. Plates may also be produced in different configurations, for example from layers of the same or different materials, or from sections of the same or different materials that may be bonded together or may be shaped to interlock together. In these ways (altering mass, materials and / or configuration of a plate) a user can select different plates to alter the range and degree of muting that can be achieved by a two or more plates when in use. In a preferred embodiment the at least two plates may include ferromagnetic material or be formed from a ferromagnetic material to attract the plates together either side of the bridge. Advantageously, since ferromagnetic plates, or plates that include one or more ferromagnetic portion are magnetically attracted to each other, the plates can be quickly and easily positioned and held in place freeing a user’s hands to secure the plates together with the adjustable attachment means. Additionally, the presence of a ferromagnetic material which is typically a magnetic metal or magnetic metal alloy can be used to adjust the weight of the plates, whereby increasing mass may enhance muting. Furthermore, the ferromagnetic material associated with the plates can also be used to enable other objects to be magnetically connected to the mute. For example, the magnetic mute may be able to receive a recording device and / or amplification device with a magnetic connection means. In this way, use of other means of attaching objects to the mute such as clips are not required, thereby minimising components that may interfere with playing or disrupt the sound produced. In some embodiments each plate includes at least two portions of ferromagnetic material at corresponding locations to align the plates. This makes fitting the mute easier and may aid with positioning the mute in the correct position or optional range of preferred positions. In some embodiments at least one of the ferromagnetic material portions may be inlaid to at least one of the plates and / or in other embodiments the ferromagnetic material is embedded within at least one of the plates. In this way the magnetic portions may be visible or hidden. For example, a ferromagnetic portion may be provided beneath the resilient deformable layer on the plate so to be embedded inside the plate and not visible in use. In embodiments that include ferromagnetic portions that may be used to receive separate objects, the plates may include portions mounted on an outer face of the plate for enhanced connection in addition to ferromagnetic portions on an inner face of the plate. In some embodiments the plates may include a mechano-chromic material which is pressure sensitive and provides a visual indication of where a force is applied across the plate. For example, the pressure sensitive material may change colour in dependence upon an applied force. In another embodiment a transducer outputs an electric signal which is in proportion to a force signal applied across the plate. The electric signal may be transmitted to a processor. Transmission may be via a wireless connection, such as by way of a Bluetooth ® wireless protocol, to a processor in a smartphone, for example. Other data may be sensed and transmitted to the processor, such as the frequency and magnitude of oscillation of the string and tension of the string. This data may be sensed using another sensor which optionally also sends data to the transmitter. Optionally the transducer may derive one or more other characteristics of the string in a static or vibrating state. The processor, which is ideally in the smartphone, is operative in accordance with application specific software (APP) to analyse characteristics of the signals, such as its frequency and magnitude and is operative in the smartphone to provide output data. The output data is stored and preferably displayed on a screen of the smartphone and may be used as a training aid to the user. An advantage of this embodiment is that it provides immediate feedback, for example by way of a visual signal, indicator or score, to a user and / or a teacher, for example during practice sessions. Optionally a memory may be used to record data for example for subsequent review or comparison purposes. Preferred embodiments of the invention will now be described, by way of examples and with reference to the Figures in which: Brief Description of Figures Figure 1A shows a front perspective view of a first embodiment of one of the plates of a mute for use on a bridge; Figure 1B shows a rear perspective view of a first embodiment of the mute; Figure 1C shows a side view of the first embodiment of the mute; Figure 1D shows the back plate of the first embodiment of the mute; Figure 1E shows the front plate of the first embodiment of the mute; Figure 2A is an overall view of another embodiment showing a (rear) plate of a mute, placed against the bridge; Figure 2B is an overall view of a corresponding front plate of a mute, placed against the bridge, in which the front plate has an elongate slot which includes a right-angle elbow; Figure 2C is an above plan view of another embodiment in which the two plates comprise at least two different layers of material; Figures 2D and 2E show front elevation views of the front plate (shown in Figure 2B) and the rear plate, (shown in Figure 2A); Figure 2F is a side elevational view of another embodiment of a mute and shows diagrammatically a quick release adjustment means device; Figure 3A shows an overall view of a second embodiment of a mute fitted to a violin; Figure 3B shows a side view of the second embodiment that is shown in Figure 2B; Figure 3C shows the second embodiment of a mute as separate disassembled items, namely: first and second plates; first and second adjustable attachment means and two adjustable nuts; Figure 3D shows an example of a mute with a single quick release adjustment means; Figure 3E is an elevation view of one embodiment of a quick release adjustable device; Figure 3F shows the similar view to Figure 3D with two quick release devices; Figure 3D shows an example of a mute with a single quick release adjustment means; Figures 4 and 5 show elevational views of inner and outer plates with apertures for receiving the adjustable attachment means; Figure 6 shows a side view of an example of the adjustable attachment means; Figures 7A, 7B, 7C and 7D show a plate in different positions relative to the bridge; Figure 8 shows in diagrammatical form a side view of the mute; Figure 3E is an elevation view of one embodiment of a quick release adjustable device. Figure 3F shows the similar view to figure 3D with two quick release devices. Figure 8B shows a plan View showing one side elevational perspective of the quick release device connected to a bridge with the locked. Figures 9A, 9B, 9C and 9D are diagrammatic views that illustrate different locations of compression that can be applied to the bridge using the mute; Figures 10A, 10B and 10C show pictorial views showing differing size and location of regions of compression which can be obtained when applying a force to the bridge by the mute; Figures 11A and 11B show examples of plates that include ferromagnetic portions; Figure 12 shows an example of a mute with apertures on a first plate and recesses on a second plate, the plate with the apertures retaining the adjustable attachment means, being curved; Figure 12B is an overall view of the embodiment with a quick release device permanently connected to one of the members; Figure 12C is another overall view of a different embodiment with two quick release devices connected; and Figure 13 is a diagrammatic overview of a system which includes another embodiment of the mute with a transducer and a wireless transmitter. Detailed Description of Figures Figures 1A to 1E show overall views of a first embodiment of a mute 100 for fitting to a stringed instrument (as shown in Figure 3A). The mute comprises two attachment plates 100A and 100B. Each attachment plate 100A, 100B is arranged, in use, either side of a bridge 250 (as shown in Figure 2B). In use the two plates 100A and 100B are connected at two separate locations, by adjustable attachment means (not shown) as explained below. Referring to Figures 1A and 1B, there are shown views of two opposing attachment plates 100A and 100B. Attachment plate 100A has apertures 110A and 11 OB for receiving attachment means, such as shanks with threaded ends, as shown in Figure 3C. Attachment plate 100B has slots 112A and 112B which allow the adjustable attachment means (not shown) to be slid easily into position so they can be deployed quickly. Figure 1C illustrates how the adjustable attachment plate 100B may be placed into a desired position opposite plate 100A (as shown by the dotted outline in Figure 1C) against the front of the bridge (not shown) so as to sandwich the bridge between the two plates 100A and 100B. Plate 100B is then located in its position by way of a rocking or see-saw action in direction of arrow A. The second adjustable attachment means, whose location is shown by P (in Figure 3C) is then received in slot 112A. Referring to Figure 1D plate 100B is then slid laterally, backwards and forwards in direction of double-headed arrow B, to engage the second adjustable attachment means, whose location is shown by Q within slot 112B. When engaged, the first adjustable attachment means is received in slot 112A, and the second adjustable attachment means is received in slot 112B as shown in Figure 1E. When plate 100B is positioned as shown in Figure 1E, the adjustable attachment means (not shown) may be deployed so as to connect the two plates 100A and 100B together so that they can be tightened to produce the benefits to the playing sound as desired. An advantage of this embodiment is that the plates 100A and 100B can be connected, when the mute is not mounted in an operational position the instrument (not shown). Referring briefly to Figure 2A to 2D, there is shown an overall view of another embodiment of the mute with a rear plate 120, placed against the bridge 130. Figure 2B shows a corresponding front plate of a mute 140, placed against the bridge 130. The front plate 140 has an elongate slot 150 which includes a rightangle elbow 152. Figures 2D and 2E show front elevation views of the front plate 140 (shown in Figure 2B) and the rear plate 120, (shown in Figure 2A). Figure 2C is an above plan view of another embodiment of a mute 118 in which the front plate comprises at least two different layers of material (118A, 118B) and the rear plate comprises at least two different layers of material (118C, 118D). Figure 2F is a side elevational view of another embodiment of a mute 118 and shows diagrammatically a single quick release adjustment means comprising a lever and a cam positioned against one surface 118 of the two layers of material 118C, 118D which form one of the plates. Figures 3A, 3B and 3C show an example of the mute 100 on a violin 200. The mute 100 has two plates 10A and 10B that are connected by two attachment means 20A, 20B. Each plate 10A, 10B has the same shape, having a substantially flat lower edge 24 that corresponds to the upper surface of the violin 200 and an arcuate upper edge 25 that corresponds to the position of the strings supported on the bridge 250 (see Figure 3A). Figure 3D shows a diagrammatic view of the mute with plates 10A and 10B being compressed by way of adjustable connector 23A and 23B. Adjustment nut 23B is as described above and adjustable connector 23A is a quick release device, of the type shown diagrammatically in Figure 2F which has a lever 103 that enables rapid connection and removal of the mute. Figure 3E is an elevation view of one embodiment of a quick release adjustable device 23A with its lever and end boss 101 connected to threaded shaft 102. Figure 3F shows the similar view to Figure 3D but with two quick release devices 23A and 23B. Levers or another part of the mute to which these are connected may be coloured differently to enable a musician to select quickly a specific quick release device which has been set to a specific tension. In the embodiment shown in Figure 4, lateral edges 26 of the plate 10A taper to a point which includes the apertures 21. On an inner face of each plate 10A, 10B is a layer of resiliently deformable material 11 A, 11B. The layers 11 A, 11B engage with the bridge 250 (see Figure 3B). Referring to Figure 3C, the adjustable attachment means 20A, 20B each comprises apertures 21A and 21B for receiving shanks 22A and 22B with threaded ends. Adjustment nuts 23A and 23B are fitted to the shanks 22A and 22B so that separation between the plates 10A and 10B, and compression against the bridge 250 (Figure 3B) can be adjusted. The layers 11 A, 11B have a raised and lower outer surface (see Figure 2C). Figure 2 shows an outer face of a plate 10A showing heads 21 of the adjustable attachment means 20A, 20B. The shank (not shown in Figure 2) of each attachment means is passed through each aperture 12 of each plate 10. Figure 5 shows an opposed outer face of a plate 10B with apertures for receiving the adjustable attachment means. The adjustment nuts 23A, 23B are turned about the threaded shanks (not shown in Figure 3) in order to move position of the plates 10A, 10B with respect to each other and to the bridge. Figure 6 shows an example of the adjustable attachment means 20, which has a screw head 21, a threaded shank 22 and an adjustment not 23 that is turned by a user gripping the nut 23 with their fingers to tighten or loosed the nut 23 on the shank 22. Figures 7A, 7B, 7C and 7D show views of a plate 10 in different positions relative to the bridge. Each plate 10 has two apertures 12 arranged at each lateral edge 26. The adjustable attachment means (not shown in Figures 7A to 7D), in use is received through the apertures 12. Figures 7A to 7D show how the plate 10 can be positioned and oriented in different ways, against the bridge 250, to alter the sound emitted from the string instrument during playing. Figure 8 shows a side view of the mute 100 without the bridge. Figures 9A, 9B, 9C and 9D are diagrammatic views that illustrate different locations of compression that can be applied to the bridge using the mute. These areas, indicated by an ‘X’ show diagrammatically where compression can be caused by the mute 100 against the bridge (not shown) to enable different areas of compression and relaxation (decompression) with the bridge. It is appreciated that two quick release adjustable devices when used may be set to provide a different amount of compression to one another, thereby enabling the user to apply different pressure to the bridge in different locations. Optionally quick release devices may be the same size, but they may be different sizes so as to enable for example access to a narrower or an inner part of the bridge. In such cases they may be coloured differently to enable a musician to select quickly a specific quick release device which has been set to provide a specific compression force. Figures 9A, 9B, 9C and 9D show pictorial diagrams to show focus points of compression that can be achieved with the mute 100, for example of the type shown in Figure 8) when the adjustment nuts 23 are tightened to different degrees. For example, in Figure 9A the adjustment nut 23 is tighter on the left or right respectively, to create an increased region of compression on one side. In Figures 9B and 9D the position of the mute on the bridge 250 is changed horizontally so that compression is increased at a higher region (Figure 9B), or lower region (Figure 9C). This effect occurs because the shape of the bridge 250 is not uniform and therefore changing the position of the mute 100 alters the degree of compression that can be applied in different regions (see Figure 3B for example in which the thickness of the bridge tapers from base to tip). The focus points of compression ‘X’ that can be achieved by the mute 100 when the adjustment means, such as nuts 23 or screws, are tightened further to increase the size of a region of compression are further illustrated in Figure 10C. When compression is reduced, by loosening the adjustable attachment means 23, the area of contact is reduced and so the amount of compression is less, as shown by the smaller regions in Figures 10A and10. Figures 11A and 11B show examples of plates 10A and 10B that include ferromagnetic portions. In Figure 10A each plate 10A, 10B has two rectangular ferromagnetic portions 30 at corresponding locations to permit attraction between inner faces of the plates 10A and 10B. In Figure 11B there is shown a plate 10 with a length of ferromagnetic material 30 inlaid along the length of the plate 10. It is appreciated that inlaid ferromagnetic material may be inlaid on an inner face, on an outer face, on both faces, the ferromagnetic material may span the width of the plate so as to be visible on both faces of the plate. The embodiment depicted in Figure 12 is an example of a novel shaped mute 300 in the form racing car. Figure 12 shows mute 300 in which a one plate 10A has apertures 302 for receiving the adjustable attachment means 304 and a second plate 10B has spindles 306 for receiving the adjustable attachment means 308. Figure 8B is a view showing one side elevational perspective of another mute 100 with a quick release device 200 connecting a pair of plates each consisting of two different materials pieces 10 and 11. At one end of the quick release device there is a countersunk nut 201 and at its other end is a rotating boss 202 and a quick release lever 200. When deployed the quick release lever 200 urges the pair of plates towards one another and so attaches the mute 100 to the bridge (not shown). Figure 12B is an overall view of the embodiment shown in Figure 12A with a quick release device permanently connected to the plate 10B. Figure 12C is another overall view of a different embodiment with two quick release devices connected the same plate 10B. A variation may be to connect a quick release device to each one of the two plates and connect them in a ‘head-to-toe’ configuration. Referring to Figure 13, there is shown a diagrammatic overview of a system which includes another embodiment of the mute 500 with a transducer 502 and a wireless transmitter 504. The transducer 502 outputs an electric signal which is in proportion to a force signal applied across the plate 506. The electric signal is transmitted to a processor 508. This may be via a wireless connection, such as Bluetooth ® wireless protocol, to a processor 508 in a smartphone 510. Other data may be sensed and transmitted to the processor 508, such as the frequency and magnitude of oscillation of the string 512 and tension of the string 512. This data may be sensed using another sensor which sends data to the transmitter 504 for transmission to a receiver 505. The processor 508 in the smartphone 510, is operative in accordance with application specific software (APP) to analyse characteristics of the signals, such as frequency and magnitude of strig vibration and any harmonics that are present and is operative in the smartphone 510 to provide output data. The output data is stored and preferably displayed on a screen 520 of the smartphone 510. The image 522 that is displayed may be used as a training aid to the user. An advantage of this embodiment is that it provides immediate feedback, for example by way of a visual signal or score, to a user and / or a teacher, for example during practice sessions. Optional a memory, such as a database 550, may be used to record data for example for subsequent review. The invention has been described by way of examples only and it will be appreciated that variation may be made to the above-mentioned embodiments without departing from the scope of invention as defined by the claims.

Claims

1. A mute for a stringed instrument which has a bridge, the mute comprises at least two plates; each plate being arranged in use either side of the bridge, wherein the at least two plates are connected one to another at two separate positions by an adjustable attachment means which enables adjustment of the separation between the plates and adjustment of a compressive force which the at least two plates apply to the bridge, wherein at least one of the adjustable attachment means includes a quick release device.

2. A mute according to claim 1 wherein at least two of the plates each has a hole or an aperture for receiving the adjustable attachment means.

3. A mute according to claim 1 or 2 including two quick release devices which connect the at least two plates one to another, so that the plates apply pressure to the bridge.

4. A mute according to any preceding claim wherein at least one of the plates has at least one slot along which the adjustable attachment means is able to slide.

5. A mute according to any preceding claim wherein at least one of the quick release devices connects the at least two plates one to another at the first position, through holes or apertures formed in two of the plates; and at least a first plate has a slot formed in it, and at least a second plate has another hole or aperture formed for receiving a second quick release device.

6. A mute according to claim 5 wherein one end of the second quick release device passes through the hole or aperture and the other ends slides into the slot so that the at least two plates can be connected one to another at the second position using one quick release device.

7. A mute according to any preceding claim wherein the at least first plate has two slots for slidably receiving one end of each of two quick release devices and the second plate has two holes through which the separate end of each of the quick release devices pass.

8. A mute according to any of claims 1 to 6 wherein the at least first plate and at least second plate each has a slot for slidably receiving one end of a quick release devices and an aperture or holes through which the separate end of each quick release devices passes.

9. A mute according to any preceding claim includes a circlip or nut or other retainer to connect and retain the, or each, quick release device with respect to the plate to which it is attached.

10. A mute according to any preceding claim wherein at least one quick release device is coloured, for example to indicate a particular pre-set force or its mass.

11. A mute according to any preceding claim wherein a marker on at least one quick release device is provided for indicating a specific compressive force setting.

12. A mute according to any preceding claim wherein the quick release device is rotatable on a boss when positioned on a plate13. A mute according to any preceding claim wherein at least one plate has a recess for receiving an end of the, or each, quick release device.

14. A mute according to any preceding claim wherein at least one quick release device comprises a shaft with a boss attached thereto and a lever which may be on a cam on an angle.

15. A mute according to any preceding claim wherein at least one quick release lever comprises a shaft or skewer rod connecting a boss with a swivel lever which has a cam or other similar means, and when deployed the cam locks in place to apply a specific compression to the two plates.

16. A mute according to any preceding claim wherein at least an inner face of each plate is shaped to correspond to the profile of the bridge.

17. A mute according to any preceding claim includes at least one layer of resiliently deformable material which in use is located between at least one of the plates and the bridge.

18. A mute according to claim 17 wherein each inner face, of the at least two plates, has a resiliently deformable layer that is in contact with opposite faces of the bridge.

19. A mute according to claim 17 or 18 wherein the at least one layer of resiliently deformable material has raised regions and lowered regions on its surface which is in contact with the bridge.

20. A mute according to any preceding claim wherein the plates are congruous, and each plate has a corresponding means for receiving the adjustable attachment means which are in register one with another.

21. A mute according to any preceding claim wherein the two separate positions are spaced apart at each end of the at least two plates and extend beyond the bridge so that the adjustable attachment means connects the at least two plates leaving a space from the bridge.

22. A mute according to any preceding claim wherein at least one adjustable attachment means comprises a head on a shank with a threaded portion at one end that receives an adjustable nut.

23. A mute according to claim 22 wherein one threaded portion has a righthand threaded part, and the other threaded portion has a left-hand thread part.

24. A mute according to any preceding claim wherein at least one of the plates has a substantially flat lower edge and a substantially curved upper edge.

25. A mute according to any of claims 1 to 23 wherein a lower edge of at least one of the plates is curved to correspond to a surface profile of the stringed instrument.

26. A mute according to any preceding claim wherein at least a first plate is of a first thickness and at least a second plate is of a second thickness.

27. A mute according to any preceding claim wherein the thickness of at least one plate varies across its length.

28. A mute according to any preceding claim wherein at least one plate is formed from layers of material.

29. A mute according to claim 28 wherein the at least one plate is formed from layers of different materials.

30. A mute according to any preceding claim wherein the at least one plate is formed from sections of different materials.

31. A mute according to claim 29 wherein the sections of different materials are bonded together to form a plate.

32. A mute according to either claim 30 or 31 wherein the sections of different materials are shaped to interlock to form the plate.

33. A mute according to any preceding claim wherein the at least two plates include a magnetic or ferromagnetic material to attract the plates together either side of the bridge.

34. A mute according to claim323 wherein each plate includes at least two regions of ferromagnetic material at corresponding locations to align the plates.

35. A mute according to either claim 33 or claim 34 wherein the ferromagnetic material is inlaid or embedded in at least one of the plates.

36. A mute according to any preceding claim wherein at least one plate includes a pressure sensitive material to provide a visual indication of where a force is applied.

37. A system includes the mute according to any preceding claim; a transducer which derives a signal from the mute which is indicative of a characteristic of a string, in either a static or vibrating state; and a wireless transmitter which is operative to transmit the signal to a wireless receiver.

38. A system according to claim 37 wherein the wireless receiver is in a smartphone which includes a memory and a display.31

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