DESCRIPTION

[0001] The present description relates to the technical field of motor vehicles and in particular it relates to a motor vehicle comprising a sound reproduction system in audio band with electromagnetic vibration exciter.

[0002] In motor vehicles, such as passenger cars, sound reproduction systems in audio band have long been used, adapted to diffuse sound signals within the passenger compartments of such vehicles, both in order to entertain the passengers by listening to music and radio broadcasts and to diffuse, within the compartment, signalling, alarm messages and the like, adapted to acoustically provide information on the status of the vehicle, the driving operation of the vehicle and/or traffic conditions, etc.

[0003] In the field of motor vehicles, on the other hand, the use of sound reproduction systems in audio band so far has been very limited. This is due to the fact that the spaces available on board of motor vehicles are typically very small and, with certain exceptions, these spaces do not allow accommodating sound reproduction devices such as players, radio receivers, audio amplifiers and traditional coil loudspeakers. Moreover, contrary to what happens in cars, motor vehicles are generally not provided with a closed or substantially closed compartment that is adapted to confine the sound emissions of the loudspeakers of the traditional sound reproduction systems and which is adapted to provide a certain acoustic isolation from the sounds and/or noise from the external environment. For this reason, in order to obtain a sound reproduction characterised by a sound power emitted enabling the driver or any passenger to adequately use the sound reproduction, conventional heavy and bulky magneto-dynamic loudspeakers are needed, which are not compatible with the spaces available on board and with the need for weight reduction required by the motor vehicle industry.

[0004] A general object of the present description is to provide a motor vehicle with a sound reproduction system in audio band which does not have the drawbacks mentioned above with reference to the prior art.

[0005] This and other objects are achieved by a motor vehicle as defined in claim 1 in the most general form thereof and in the dependent claims in some particular embodiments thereof.

[0006] The invention will be better understood from the following detailed description of embodiments thereof, made by way of an example and therefore in no way limiting with reference to the accompanying drawings, in which:

- figure 1 shows a perspective view of a first embodiment of a motor vehicle comprising a sound reproduction system in audio band;

- figure 2 shows a plan view of the motor vehicle in figure 1, which schematically shows a sound reproduction system in audio band comprising at least one driver device and an electromagnetic vibration exciter applied to a cover or screening panel of the motor vehicle;

- figure 3 shows a perspective view of a second embodiment of a motor vehicle comprising a sound reproduction system in audio band;

- figure 4 shows a perspective partially sectional view of a first embodiment of a system of attachment of the at least one electromagnetic vibration exciter to the cover or screening panel of the motor vehicle in figure 1 or 2;

- figure 5 shows a perspective partially sectional view of a second embodiment of a system of attachment of the at least one electromagnetic vibration exciter to the cover or screening panel of the motor vehicle in figure 1 or 2;

- figure 6 shows a perspective partially sectional view of a third embodiment of a system of attachment of the at least one electromagnetic vibration exciter to the cover or screening panel of the motor vehicle in figure 1 or 2; - figure 7 shows a perspective partially sectional view of a fourth embodiment of a system of attachment of the at least one electromagnetic vibration exciter to the cover or screening panel of the motor vehicle in figure 1 or 2; - figure 8 shows a perspective partially sectional view of a fifth embodiment of a system of attachment of the at least one electromagnetic vibration exciter to the cover or screening panel of the motor vehicle in figure 1 or 2;

- figure 9 shows a perspective partially sectional view of a sixth embodiment of a system of attachment of the at least one electromagnetic vibration exciter to the cover or screening panel of the motor vehicle in figure 1 or 2; and

- figure 10 shows a perspective partially sectional view of a seventh embodiment of a system of attachment of the at least one electromagnetic vibration exciter to the cover or screening panel of the motor vehicle in figure 1 or 2 ;

- figure 11 shows a possible embodiment of frequency response curve of the driver device in figure 2;

- figure 12 shows a plan view of a possible embodiment of an electromagnetic vibration exciter of the sound reproduction system in figure 2;

- figure 13 shows a plan front elevation view of the electromagnetic vibration exciter in figure 12/ - figure 14 shows a plan view of a further embodiment of an electromagnetic vibration exciter of the sound reproduction system in figure 2 ;

- figure 15 shows a lateral sectional view of the electromagnetic vibration exciter in figure 14;

- figure 16 shows a perspective view of a third embodiment of a motor vehicle comprising a sound reproduction system in audio band; and

- figure 17 shows a plan view of the motor vehicle in figure 16.

[0007] In the accompanying figures, elements which are equivalent or similar will be indicated by the same reference numerals.

[0008] Figures 1 and 2 show a first embodiment of a motor vehicle 1, which in the particular example shown is, without thereby introducing any limitations, a three- wheeled motorcycle or tricycle, comprising two front steering wheels 2 and a rear wheel 3.

[0009] Figure 3 shows a second embodiment of a motor vehicle 1, which in the particular example shown is, without thereby introducing any limitations, a two- wheeled motorcycle and in particular a two-wheeled scooter, having only one front wheel 2 and one rear wheel 3.

[0010] Hereafter in the present description, reference will be made to a generic motor vehicle 1, meaning that the description of the following is applicable generally to any type of motor vehicle 1 comprising:

- a bearing structure;

- at least two wheels 2, 3 either directly or indirectly constrained to the bearing structure;

- a traction motor 4, for example thermal or electric or hybrid, constrained to the bearing structure and a transmission system 5 adapted to transmit the movement from the traction motor 4 to at least one of the two wheels 2, 3;

- at least one cover or screening panel 6, 7, 8 attached to the bearing structure of motor vehicle 1.

[0011] The bearing structure for example is the frame of motor vehicle 1 or any structure of motor vehicle 1 coupled to the frame of motor vehicle 1 and having a support function of other structural elements of motor vehicle 1.

[0012] By cover or screening panel it is meant any panel of motor vehicle 1 such as a panel of the body and/or the fairing of the motor vehicle and/or an internal compartment of motor vehicle 1, such as a glove compartment or a helmet holder, and/or a footboard of motor vehicle 1, indifferently having a either a functional or aesthetic function. By screening panel it is meant, for example, a panel forming part of a windshield of motor vehicle 1 and/or a windscreen of motor vehicle 1.

[0013] Motor vehicle 1 comprises a sound reproduction system 20 , 21 in audio band adapted to reproduce sound signals in audio band, such as signals adapted to be perceived by the human ear and bearing musical, vocal, signalling, status information of the motor vehicle or traffic or road conditions. The sound reproduction system in audio band 20, 21 comprises a driver device 20 and at least one elastic suspension electromagnetic vibration exciter 21 applied to said at least one cover or screening panel 6, 7, 8 of motor vehicle 1. Said at least one elastic suspension electromagnetic vibration exciter 21 is operatively connected to the driver device 20 for receiving as input an electric driving signal and provide as output mechanical stresses adapted to make said panel 6, 7, 8 vibrate in a controlled manner for reproducing an acoustic signal in the audio band via acoustic waves produced by the controlled vibration of said panel. A particular indicative and non limiting example of elastic suspension electromagnetic vibration exciter is described in US patent 8,130,086. Another example is described in US patent 6,377,145. A further example is described in US patent application 2006/0266967. [0014] Preferably, the elastic suspension electromagnetic vibration exciter 21 is applied to a locally flat portion of panel 6, 7, 8. More preferably and non limitingly, said locally flat portion has a minimum area of 15 cm ² and more preferably and non limitingly equal to 25 cm ² .

[0015] According to a possible embodiment, motor vehicle 1 comprises a front shield 10 attached to the support structure of motor vehicle 1, and the cover or screening panel 6, 7, 8 to which exciter 21 is applied is a panel included within the front shield 10. For example, with reference to figures 1 and 2, a windshield 6 is applied to the front shield 10 and in this case, exciter 21 is within the front shield 10 in the vicinity of windshield 6 so that the windshield acts as a sound conveyor adapted to direct the sound waves towards the driver. In the particular example shown in figures 1 and 2, a pair of exciters 21 is provided within the front shield 10, preferably mutually arranged on opposite sides with respect to the main longitudinal extension axis A-A of motor vehicle 1.

[0016] In general, according to a preferred embodiment in a motor vehicle 1 comprising a forecarriage 10 and a backcarriage 12, said at least one elastic suspension electromagnetic vibration exciter 21 (hereafter also referred to as "exciter 21") comprises at least two pairs of exciters 21 both attached to the forecarriage 10. In the example in figure 2, two pairs of exciters 21 are provided, applied at the forecarriage of motor vehicle 1, of which one pair 21 is applied above (in the vicinity and below windshield 6) and the other pair is applied to portions of the hull of the front shield 10 arranged approximately in a median position between handlebar 13 and platform 14 of motor vehicle 1. In the example in figure 3, two pairs of exciters 21 are provided, applied to the forecarriage of motor vehicle 1, of which one pair is applied to the front shield 10, internally to shield 10 in a portion of the shield close to handlebar 13 (arrow "a", in which exciters 21 of the pair are mutually arranged on opposite sides with respect to the longitudinal axis of motor vehicle 1) , and the other pair is applied to portions of the hull of the front shield 10, internally to shield 10, in a portion of shield 10 close to platform 14 (arrow "b", in which exciters 21 of the pair are mutually arranged on opposite sides with respect to the longitudinal axis of motor vehicle 1) .

[0017] In the embodiment in figures 1 and 2, in addition to one or two pairs of exciters 21 provided on the forecarriage of motor vehicle 1, a pair of exciters 21 is also provided on backcarriage 12 of motor vehicle 1, and in particular under saddle 11 or at the sides of saddle

11, applied to an internal panel 8 which delimits a storage compartment located underneath saddle 11.

[0018] According to a general embodiment, motor vehicle 1 includes a forecarriage 10 and a backcarriage 12 and said at least one exciter 21 comprises at least one pair of exciters 21 both attached to forecarriage 10 or both to backcarriage 12, mutually arranged on opposite sides with respect to the main longitudinal extension axis A-A of motor vehicle 1.

[0019] According to a further embodiment, in which motor vehicle 1 comprises a forecarriage 10 and a backcarriage

12, the at least one exciter 21 comprises:

- at least a first pair of electromagnetic vibration exciters 21 both attached to forecarriage 10 and mutually arranged on opposite sides with respect to axis A-A, to a same panel or to two different panels of forecarriage 10; and

- at least a second pair of electromagnetic vibration exciters 21 both attached to backcarriage 12 and mutually arranged on opposite sides with respect to axis A-A, to a same panel or to two different panels of backcarriage 12.

[0020] According to one embodiment, exciter 21 may be either directly or indirectly attached to a surface of a relative cover or screening panel 6, 7, 8 by means of an adhesive. The attachment by means of an adhesive (i.e. attachment by gluing) nevertheless has some drawbacks. The surface to which the electromagnetic vibration exciter 21 is bonded, either directly or indirectly, must be locally flat, clean and of a material compatible with the adhesive used. Like any gluing, it is vulnerable precisely in these situations:

- uneven surface: it may make the application of exciter 21 impossible;

- surface not clean at the time of gluing: it may cause the detachment of exciter 21 and the resulting loss of efficiency of the system;

- surface of a material not compatible with the glue: it may cause the detachment of exciter 21 as in the previous point ;

surface or environment exposed to significant temperature changes: it may cause the softening of the adhesive and the consequent detachment of exciter 21.

[0021] For the above reasons, according to a possible embodiment, the sound reproduction system in audio band further comprises a fastening system adapted to fasten exciter 21 to panel 6, 7, 8 comprising:

- at least one support device 31 of exciter 21 comprising a device body 32 provided with a first fastening element 33 adapted to co-operate with a complementary first fastening element 23 of exciter 21;

- at least one fastening device 26, 28, 36 adapted to cross the device body 32 or engage in the device body 32 to fasten the support device 31 to panel 6, 7, 8 permitting the continuous or discrete regulation of a reciprocal fastening orientation between the support device 31 and panel 6, 7, 8, and thus between exciter 21 and panel 6, 7, 8.

[0022] For example, the first fastening element 33 of the support device 31 is an externally threaded collar 33 which protrudes from the device body 32 and the first complementary fastening element 23 of exciter 21 includes an internally threaded recess 22 within which it is possible to screw the externally threaded collar 33 of the support device 31.

[0023] According to an embodiment, the above fastening device 26, 28, 26 comprises a clamping device 26, 28, such as a screw 26, 28, adapted to cross a through opening defined in panel 6, 7, 8 to engage in a seat provided in body 32 of the support device 31 or to cross a through opening defined in body 32 of the support device 31. Said clamping device 26, 28 is for example a metric screw 26 or a self-tapping screw 28.

[0024] According to an alternative embodiment, panel 6, 7, 8 comprises at least one fastening element 29, for example shaped as a spacer column, projecting with respect to panel 6, 7, 8 and inside which a hole is defined. In this embodiment, the fastening device 26, 28, 36 comprises a clamping element 36, for example a self- tapping screw, adapted to engage in said hole.

[0025] According to a further embodiment, said at least one support device comprises:

- a first support device 31 comprising said device body 32;

- a ^■ second support device 41 adapted to be fastened at a distance from panel 6, 7, 8 and to which the first support device 31 is fastened in a position interposed between said exciter 21 and the second support device 41.

[0026] The above embodiments defined in general will be better contextualized by describing some particular non- limiting examples of fastening systems with reference to figures 4 to 10.

[0027] In figure 4, the fastening system comprises a support device 31 having a body 32 and an externally threaded collar 33 adapted to be screwed inside a threaded seat 23 provided in body 22 of the electromagnetic vibration exciter 21. The support device 31, for example made of plastic, acts as a spacer element between exciter 21 and panel 6, 7, 8 and is therebetween physically interposed and tightened. The support device 31 comprises a through opening facing a corresponding through opening provided in panel 6, 7, 8 and the fastening system includes a fastening device comprising a clamping element 26 (for example, a metric screw 26) , which crosses both said openings, and a nut 27 adapted to engage with screw 26. In this embodiment, panel 6, 7, 8 and the support device 31 are clamped between the head of screw 26 and nut 27.

[0028] The embodiment in figure 5 differs from the embodiment in figure 4 in that the clamping element comprises a screw 28, for example self-tapping, adapted to engage with the support device 31 to secure the support device to panel 6, 7, 8.

[0029] In the embodiment in figure 6, panel 6, 7, 8 comprises at least one fastening element 29, for example shaped as a spacer column, projecting with respect to panel 6, 7, 8 (preferably towards the inside of the hull of motor vehicle 1) and inside which a hole is defined, and the fastening device comprises a clamping element shaped at least as a screw 36 adapted to cross the support device 31 to engage into said hole.

[0030] In the embodiment in figures 7 and 9, panel 6, 7, 8 comprises a plurality of fastening elements 29 (preferably, it comprises three fastening elements 29), for example shaped as spacer columns, projecting with respect to panel 6, 7, 8 and inside which a respective hole is defined. In addition to the first support device 31, the support device comprises a second support device 41 adapted to be fastened at a distance from panel 6, 7, 8 and to which the first support device 31 is fastened in a position interposed between exciter 21 and the second support device 41. The second support device 41 is fastened to panel 6, 7, 8 by screws 36 that cross the second support device 41 and are inserted into the fastening elements 29 of panel 6, 7, 8. The first support device 31 is coupled to the second support device 41 through a pin 26 and a nut 27. The embodiment in figure 8 differs from the embodiment in figure 7 in that in figure 8, the second support device 41 is operatively interposed between panel 6, 7, 8 and the first support device 31.

[0031] The embodiment in figure 9 differs from the embodiment in figure 8 in that in figure 9, the support device 31 is equal to the integration of the support devices 31 and 41 shown in figure 8 in a single piece.

[0032] In the embodiment in figure 10, the cover or screening panel 6, 7, 8 of motor vehicle 1 to which exciter 21 is applied is a two-layer panel comprising a first relatively outward layer 6', 7', 8' and a second relatively inward layer 6, 7, 8 between which an interspace is defined and exciter 21 is attached to the second relatively inward layer 6, 7, 8. The two layers may be of two different materials, for example the outermost one of a metal material and the innermost one of a plastic material. While figure 10 shows in particular the fastening system in figure 4, it is clear that in case of two-layer panel, any of the fastening systems described with reference to figures 4 to 9 may be provided for fastening exciter 21 to the relatively inward layer 6', 7', 8'.

[0033] According to an embodiment, the driver device 20 comprises an amplifier operatively connected to exciter 21 and a first connection interface adapted to connect to said amplifier an input device (or "source") adapted to supply to the amplifier an electric signal to be amplified for driving exciter 21. For example, said connection interface is a wireless interface, such as a Bluetooth interface. According to a further embodiment, said connection interface is a wired interface, such as a USB interface or an analogue audio interface.

[ 0034] According to an embodiment, said input device (or "source") comprises a device for playing and reproducing audio digital or multimedia files, such as for example an mp3 player or a smartphone.

[ 0035] According to an embodiment, the driver device is connected to another electronic or communication control unit located on board of the motor vehicle (for example to the control unit of motor vehicle 1) .

[0036] In order to prevent undesired situations of unnecessary consumption of the energy stored in the battery of motor vehicle 1, it is possible to provide suitable devices for the switching on and off timing of the driver device and the relative wireless interface (if provided) . Below is a non limiting example of operation if the sound, reproduction system described above is provided with a wireless interface for direct or indirect connection through an electronic unit of motor vehicle 1, an input device (such as a smartphone) to the driver device 20, assuming that the sound reproduction system in audio band is operatively coupled either directly or indirectly to the key on/off switch of motor vehicle 1.

[0037] The sound reproduction system may be "woken up" by the ignition switch ("key on") that activates the power and the wireless interface. In the first seconds of ignition, the sound reproduction system is available for the wireless pairing with an input device that acts as a sound source (smartphone or the like) and hereafter referred to "source".

[0038] If the source sends a signal to be reproduced, the sound reproduction system through the driver device 10 and the at least one electromagnetic vibration exciter ^■ 21 and panel 6, 7, 8 plays it and makes it audible.

[0039] The sound reproduction system preferably has an equalization designed specifically for the particular type of transducer 21 used, for the material of panel 6, 7, 8 and for the arrangement of exciter 21; however, equalization and volume may be changed directly from the source. It is possible to envisage that the sound reproduction system turns off according to the following rules :

- no connection: upon waking, the system does not find any wireless sources; once the connection time has expired (in the order of tens of seconds) , the system returns to sleep up to a new "key on";

- connection lost: the wireless connection is lost and the system does not find any other wireless sources; once the connection time has expired (in the order of tens of seconds), the system returns to sleep up to a new "key on";

- vehicle off: at the "key off", the system remains powered on and operating for a predetermined number of minutes (e.g. 15-20), after which it returns to sleep and operating as described above up to a new "key on", if the connection is lost in the operating time in "key off", the returns to sleep up to a new "key on";

- if in the time of operation in "key off" the battery charge level of motor vehicle 1, e.g. controlled by the system itself, falls below a preset threshold value, the system shuts down and remains insensible to the new "key on" until the battery charge does not return higher than the preset threshold value.

[0040] With reference to figure 11, according to a particularly advantageous, the driver device 20 has a passband frequency response, comprising a first gain peak at a first frequency fmaxl, a second gain peak ad a second frequency fmax2 greater than said first frequency and a gain local minimum at a third frequency fminl comprised between said first frequency fmaxl and said second frequency fmax2.

[0041] According to an embodiment, the above frequency response for example is the frequency response of the amplifier comprised in the driver device 20, for example if in the driver device no equalizer is provided in input or in output from the above amplifier. In an alternative embodiment, the driver device 20 includes an equalizer in input or in output from the amplifier, and the above frequency response is the frequency response of the cascade between said amplifier and said equalizer. In each of the above embodiments, the driver device 20 is preferably configured in such a way that the above frequency response is programmable via software, such as through an external processor, and can be stored in the driver device for example in a firmware of said driver device .

[0042] With reference to figure 11, according to an embodiment :

- said first frequency fmaxl is included in the frequency range 100Hz-300Hz;

- said second frequency fmax2 is a frequency greater than 7 kHz;

- said third frequency fminl is included in the range 400Hz-6kHz and preferably in the range 500Hz-3kHz.

[0043] For example:

- said first frequency fmaxl is equal to or approximately equal to 200Hz;

- said second frequency fmax2 is equal to or approximately equal to 10kHz;

- said third frequency fminl is equal to or approximately equal to 900Hz.

[0044] Preferably, the frequency response at said third frequency fminl has a gain of at least 3dB lower than each of the gains of the frequency response at said first frequency fmaxl and said second frequency fmax2. More preferably, the frequency response at said third frequency fminl has a gain of at least 5dB lower than each of the gains of the frequency response at said first frequency fmaxl and said second frequency fmax2.

[0045] According to a further embodiment, the frequency response at said second frequency fmax2 has a gain of at least 3dB higher than each of the gains of the frequency response at said first frequency fmaxl and said third frequency fminl. Preferably, said frequency response at said second frequency fmax2 has a gain of at least 5dB higher than each of the gains of the frequency response at said first frequency fmaxl and said third frequency fminl.

[0046] It has been noted that the above embodiments described with reference to the frequency response advantageously allow preventing unpleasant dissonance and distortions produced by vibrations of the panels typically carried on board of motor vehicles to which the above exciters can be applied.

[0047] With reference to figures 12 and 13, according to a preferred embodiment, the elastic suspension electromagnetic vibration exciter 21 includes:

- a coil (not shown in the figures) powered by a current or a driving signal provided in output by the driver device ;

a relatively rigid housing device 60 of the coil attached to the panel of the motorcycle and a magnetic yoke 64 coupled to the housing device 60 of the coil through a relatively elastic suspension 62 with respect to said relatively rigid housing device 60.

[0048] Preferably, the magnetic yoke is rigidly coupled to an oscillating mass integral in the movement of the magnetic yoke relative to the coil. Preferably, the magnetic yoke is housed within a housing coupled through the elastic suspension 62 to the relatively rigid housing device 60 of the coil.

[0049] Preferably, the elastic suspension includes one or more elastic arms, for example curvilinear. In the particular example shown, the elastic suspension comprises three elastic curvilinear arms 62. Each of said arms 62 has an end portion attached to the housing device 60 of the coil, e.g. to respective columns that protrude from the housing device 60. Moreover, as shown in figures 12 and 13, preferably the housing device of the coil includes two connecting elements 66 to power the coil through a current or a driving signal.

[0050] According to a particularly preferred embodiment, with reference for example to figure 5 and 12, the housing device 60 of the coil includes the above described first complementary fastening element 23 of exciter 21 so that the housing device 60 can be fastened to a support device 31 of exciter 21. For example, the housing device 60 includes a threaded seat 23 already described with reference to the previous figures.

[0051] Figures 14 and 15 show a possible variante embodiment of the elastic suspension electromagnetic vibration exciter 21.

[0052] It is noted that the above description of motor vehicle 1 also corresponds to the description of a sound reproduction system for motor vehicle 1, motor vehicle 1 including :

a bearing structure and at least two wheels 2, 3 constrained to the bearing structure;

- a traction motor 4 constrained to the bearing structure and a transmission system 5 adapted to transmit the movement from the traction motor 4 to at least one 3 of the two wheels 2, 3;

- at least one cover or screening panel 6, 7, 8 attached to the bearing structure;

wherein the sound reproduction system 20, 21 in audio band is adapted to reproduce sound signals in audio band such as musical, vocal, signalling, status signals and comprises a driver device 20 and at least one elastic suspension electromagnetic vibration exciter 21 adapted to and configured for being applied to said panel 6, 7, 8 and operatively connected to the driver device 20 for receiving an electric driving signal in input and to supply mechanical stresses in output adapted to make said panel 6, 7, 8 vibrate in a controlled manner for the reproduction of an acoustic signal in audio band by means of acoustic waves produced by the controlled vibration of said panel;

wherein the sound reproduction system 20, 21 comprises a fastening system, adapted to fasten said exciter 21 to panel 6, 7, 8, comprising:

at least one support device 31 of the exciter 21 comprising a device body 32 provided with a first fastening element 33 adapted to co-operate with a complementary first fastening element 23 of exciter 21; - at least one fastening device 26, 28, 36 adapted to cross said device body or engage in said device body to fasten the support device 31 to the panel 6, 7, 8 permitting regulation of a reciprocal fastening orientation between the support device and the panel 6, 7, 8.

[0053] Said sound reproduction system can be coupled to the motor vehicle already in the production/preparation phase of the motor vehicle or it can be produced and sold as a kit applicable to the vehicle.

[0054] According to what described above, it is therefore possible to understand how a motor vehicle of the type described above allows achieving the objects mentioned above with reference to the prior art. [0055] The principle of the invention being understood, the manufacturing details and the embodiments may widely vary compared to what described and illustrated by way of a non-limiting example only, without departing from the scope of the invention as defined in the accompanying claims .

[0056] For example, the sound reproduction system may be applied to motorcycles other than those in figures 1-3. Figures 11 and 12 show by way of example a further type of motorcycle, which in particular is a "naked" type motorcycle. Also in this case, the resonant mode electrodynamic transducers 21 may be applied to side cover or screening panels of small size, such as sides panels arranged at the sides of the fuel tank 51 and/or panels underneath saddle 11. In a further embodiment, said resonant mode electromagnetic vibration exciter 21 may be applied to a panel of a containment accessory either directly or indirectly attached to the bearing structure of the motor vehicle, such as a side bag or a glove compartment.

[0057] According to an embodiment, the driver device of the sound reproduction system described above may be configured to drive the at least one exciter 21 to vary the volume of the sound signal in audio band emitted, for example as a function of motion parameters of motor vehicle 1, such as instant speed and/or acceleration thereof. To this end, the driver device may be provided with a module for estimating the above parameters, or it may be provided with at least one input for receiving at least one signal containing information on said parameters .