VEHICLES FOR PASSENGERS THAT INCLUDE LOUDSPEAKERS THAT COMPRISE ACOUSTIC EMISSION ELEMENTS IN THE FORM OF A PANEL
TECHNICAL FIELD The invention relates to vehicles for passengers and more particularly to passenger vehicles that incorporate loudspeakers comprising acoustic emission elements in the form of a panel. BACKGROUND OF THE ART The embodiments of the present invention utilize elements of nature, structure and general configuration and / or specifically achievable through the implementation of the teachings of our application PCT 097/09842. Such elements thus have the ability to sustain and propagate vibrational energy inputs by bending waves in an operating area (s) that extend transversely of the thickness, frequently but not necessarily to the edges of the element (s). ); they are configured with or without anisotropy of flexural rigidity to have vibration components in resonant mode distributed through said area (s) in a manner beneficial to the acoustic coupling with the ambient air; and have predetermined preferential locations or sites within said area for excitation means, particularly operationally active or moving part (s) of the same effective in relation to the acoustic vibrational activity in said area (s) and signals , usually electrical, corresponding to the acoustic content of such vibrational activity. Elements such as the above are called in the presently distributed acoustic radiators and are assumed to be characterized as in the aforementioned PCT application W097 / 09842 and / or otherwise as specifically provided herein. This invention relates particularly to acoustic devices in the form of resonant acoustic emission loudspeakers for use in passenger vehicles such as automobiles, aircraft, boats, trains, etc., and with vehicles incorporating such loudspeakers. SUMMARY OF THE INVENTION The invention is a vehicle that has a behavior for passengers characterized by a loudspeaker in the passenger compartment, comprising an acoustic radiator in distributed mode and a driver installed on the radiator to vibrate the radiator making it resonate. The radiator can be integrated in a passenger seat in the vehicle or in a door inside the passenger compartment. The radiator can be integrated into the interior of the passenger compartment, for example on a wall, floor or ceiling. Thus, the radiator can be integrated into the roof covering in a car or the like. A plurality of such radiators can be installed inside the vehicle. The vehicle may comprise a fibrous or plastic molded component in or forming part of the passenger compartment, and the radiator may be integrated with the component. The radiator may comprise a rigid light panel with a cellular core sandwiched between the coating layers, and wherein one of the coatings is integrated into the molded component. Said coating can be thin compared to the average thickness of the component wall. Said lining may be surrounded by a groove or groove in the component, the groove defining an elastic ring for the radiator, and the groove helping to define a region of bending operation in distributed mode. From another aspect, the invention is a vehicle component comprising a loudspeaker having a distributed-mode acoustic radiator and an exciter installed on the radiator to vibrate the radiator to make it resonate. Using the principle for the distributed mode speaker described in our International application 097/09842, it is possible to employ suitable existing structures, either directly or by adaptation or modification, or by original design, to operate as effective speakers. The operation in distributed mode indicates that a beneficial diffusion of the modal resonances in a structure intended to operate as an acoustic radiator can be favored. The principle teaches structure properties, geometry and driving point (s) that promote good modal density for wide range sound reproduction. Some structures, for example existing prefabricated panels or the like can naturally have such property in the frequency range of interest, for which an appropriate mathematical and mechanical analysis will determine the driving point (s) and the optimal exciters and their characteristics for an output useful acoustics. Obviously where existing or installed structures are suitable there is potentially a high convenience, utility and decorative value and additionally a cost benefit for the additional operation / inclusion of a loudspeaker, either for a music application or speech for example hands-free mobile telephony to improve security. Such a class of loudspeaker provides weight savings and / or greater impact safety for the occupants of the vehicle. Subject to structural and acoustic analysis including the effect of the potential air load, an interior door panel or a shelf for packages or its equivalent or existing roof cladding may benefit from modification to its facilities or by the addition of parts for increase the rigidity, of sections or panels, to result in a performance closer to the expected distributed mode, in the expected range of operation. Alternatively, these panel units, compatible or otherwise with the existing practice, can be structured and designed so that they have potential in a distributed way for vehicle interiors and general buses, or dimensions smaller than those of rooms, for example, railroad cars , buses, etc., in accordance with the principles described in our International Application W097 / 09842. For use in automobiles the principle of distributed mode is particularly appropriate, since the acoustic element can be robust, resistant to water and to the environment and does not require a cover or opening grid, or protection for its effective operation. In fact, the acoustic part of the panel can be completely integrated so that no external indication of its presence is required, this is also for the interior design where the visual presence of speaker systems is avoided. When sound systems are incorporated into vehicles, the distributed mode principle allows them to be fully integrated into prefabricated units including related services, such as ceiling lights and related control and deployment technology supplied by something as small as a wired harness to reduce the installation cost. In addition, the integration of more advanced devices in, for example, the roof coating of a vehicle, adds engineering value to this product. While distributed mode speakers are capable of, and are generally designed to operate on, a wide frequency range, in particular only to achieve the highest audible frequencies without the use of additional driving elements or cross-linking networks, some panel structures themselves provide the effective operation in the lower frequency range obeying their fundamental frequency of relatively low bending. As long as incorporated elements or otherwise, of distributed-mode speakers are used for the usual range of medium and high frequencies, the naturally low bending frequencies for the structural or modular panels in question can be used for the reproduction of sound which they are optimized in the low frequency range to work congruently with the units in the high range. The result is an additional beneficial operation of such a panel with dual purpose while the low frequency range can be extended up to the range usually covered by the so-called loudspeaker box-type units for sub-bass sounds, characterized by the operation in the range below 150 Hz and that can extend down to the audible limit of 20 Hz, or approximately, this lower limit being still detectable for human perception and capable of improving the enjoyment of music signals reproduced from wide recorded bandwidth. Larger structural panels of heavier construction of bonded resin compounds of combinations of these and similar materials will have modal resonances that extend to the low range and can be driven by a number of electromagnetic energizers including those designed specifically to satisfy speakers in a distributed manner as those described in our International applications W097 / 09859, 097/09861, W097 / 09858, optimized by driving force and natural resonance to fit appropriately to heavier larger panels. The integration of sound systems with the design of the vehicle, also with the lighting units is an important aspect of modern practice. The principle of the distributed mode horn is particularly appropriate for those applications where non-obstructive sound systems can be designed, yet completely hidden. Full range types of loudspeaker or other resonant panels can be augmented by distributed mode resonant panels, which are designed to be effective in the low range. Low range sounds are essentially non-directional, which largely eliminates restrictions on their location. Thus, low range distributed mode panels can advantageously be placed under seats in a protected area or incorporated in the lower seat panel. Vehicle components that are suitable for low frequency operation with electrodynamic exciters include package shelves, roof cladding and interior door panels. The structure of a roof covering can be multi-layered, with a structural base of resinated fiber covered by an acoustically porous thin foam and by a fabric or other decorative covering. In one embodiment the base of the roof covering is perforated by one or more openings in which spaced-out horns can be elastically supported to provide one or more sound reproduction channels conveniently above the heads of the passengers, the sound easily transmitted through the porous layer. These separate distributed-mode loudspeakers are more appropriate for the middle and upper frequency range and the low range is then reproduced preferably by resonating the roof lining structure with an appropriate electrodynamic exciter. The particular virtue of a distributed mode horn in this design is the absence of a hot spot or proximity effect which provides superior sound distribution for the passengers of the vehicle. During manufacturing, small distributed mode horns can be molded in place in a roof liner or similar to simplify construction. To avoid the possibility of energy overload, and the consequent need for repair, thermal limiters, for example, self-adjusting resistors of positive temperature coefficient can be incorporated in the wired harness to protect the exciters. A loudspeaker according to the present invention can be incorporated in a conventional vehicle using, for example, existing or partially modified surfaces, or by molding and appropriately assembling a loudspeaker panel in a distributed manner for the different coatings and accessories of the vehicle, for example in panels of the roof covering far from the contact with the head of the occupant. A distributed-mode acoustic radiator designed to operate at low frequencies, that is, a subwoofer, can be placed in places such as the area under the seats or on the backs of the seats, and can also be adapted to the whole of the roof lining of appropriate stiffness. The reproduction of medium-high frequency sound can be achieved using distributed-mode loudspeaker panels coupled to, or installed in the vacuum formation or other molding process of the internal accessories, in particular the roof covering, the door lining, the package rack, the parasol or the fender of a car. The frequencies of the bass can be produced by applying an appropriate exciter to a roof lining or to the rear rack and / or by the use of separate panels in a distributed manner coupled to the lower sides of the seats, to the backs of the seats or linings of the doors or even the coatings of the floors. In a particular application, the cavities for the feet in the vehicles can be used to amplify the frequencies of the bass as a horn for the radiators of the panel installed in such a location. When the horns are close to the heads of the passengers, especially in the applications of the roof lining or the head rest, a good order noise elimination or a bandwidth and elimination ratio can be obtained, as a benefit additional in relation to appropriate signal processing systems, known per se. Due to the very wide dispersion characteristics of the speakers in distributed mode and the diffuse nature of the sound, a uniform distribution of sound is achieved in the cab of the vehicle with a good signal-to-noise ratio. A further improvement of the "tonal balance" and also a "dynamic path noise reduction", that is, a noise elimination can be achieved by DSP (Digital Signal Processing) methods due to the very uniform nature of the power distribution of the sound of the speaker panels distributed mode. Due to the electrically compatible nature of distributed-mode speaker panels using electro-dynamic drivers, existing electronics and amplification can be used. Due to the current manufacturing procedures adopted by vehicle manufacturers, they prefer to purchase fully functional pre-tested subassemblies. The above applications themselves provide such preferred methods of manufacturing and sub-contracting. BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated diagrammatically, by way of example, in the accompanying drawings, in which: Figure 1 is a plan view of a roof or roof covering for an automobile, constructed in accordance with the present invention; Figure 2 is a partial cross-sectional side view of the roof covering of Figure 1; Figure 3 is a perspective view of the front portion of a car; Figure 4 is a plan view corresponding to figure 3, and figure 5 is a view of part of the interior of a car. BEST MODES FOR CARRYING OUT THE INVENTION Figures 1 and 2 show a roof or roof covering (1) for a car (not shown) whose roof covering comprises a main body
(2) of a fibrous material impregnated with resin which is formed for its configuration by molding and which is covered on its lower surface with a layer of elastic foam (3), for example of plastic or rubber, which in turn it is covered by a layer of decorative covering (4) of textile material or the like. As shown, four resonant acoustic loudspeaker speakers in the form of a panel (5), as described in International Application W097 / 09842, are provided within the thickness of the roof covering and are installed in the roof covering in such a way that They are usually placed above the heads of the occupants of the car. The four speakers (5) are provided as medium / high frequency speakers. In addition, an opposite pair of vibration exciters is installed directly on the body of the roof covering, to excite the roof covering at low frequencies in the form of a subwoofer which operates as an acoustic radiator in a distributed manner according to it is described in International application 097/09842. The vibration exciters may be of the kind described in International applications Nos. 097/09859, 097/09861, W097 / 09858 and are preferably inertial electrodynamic devices. A wired harness (7) that provides electrical power to the various loudspeakers and other components such as interior lights (18) are integrated with the roof lining. It may be desirable to provide current limiters (8) in the wiring (7) to the loudspeakers to protect the exciters against overload. A rearview mirror (19) is shown installed on the roof covering. As shown in Figure 2, the medium / high frequency loudspeakers (5) are provided in cavities (9) formed in the thickness of the body (2) of the roof covering and by local reduction of the thickness of the foam layer elastic (3) wherein the foam layer is acoustically transparent. Monoliths generally in light rigid rectangular panels (10), for example of fiber-impregnated plastic forming resonant acoustic radiators and made in accordance with the teachings in W097 / 09842 are installed in the respective cavities (9) on separate elastic suspension elements (11), for example, of a foamed elastomeric material, which are installed on the body and fixed to the panel (10) close to its edges. A vibration exciter
(12) is installed on the panel (10) to throw the bending waves towards the panel and is placed on the panel as discussed in W097 / 09842. The exciters (12) can be electrodynamic and can be of the inertial variety. Figures 3 and 4 show a car (15) in which the roof and the roof covering were omitted for the sake of clarity, and illustrates that the acoustic emission loudspeakers (5) of the class described above are also provided in the inner liner (14) of the passenger footwell (13) and may be beneficial by such placement since the partially enclosed volumes of such foot spaces may act as horns or resonators to improve the acoustic signal. The radiators can be low frequency, that is, loudspeakers, subwoofers for bass sounds. In Figure 5, a car (15) of the above-described kind is additionally equipped with loudspeakers (5) of distributed mode acoustically integrated in the sun visors (17) coupled to the upper part of windscreen (16) of the automobile. The visors (17) incorporate resonant panels (10) excited by vibration exciters (12) as described above. The panel shape of a distributed mode acoustic radiator makes it particularly suitable for such purpose. By careful, balanced sound levels, the sound source of the lens hood can be used to provide improved image direction and front location for people sitting in the front of the vehicle. For rear passengers an increased location can be achieved by additional horn elements that work in addition to the main radiators of the roof / shelf for packages: these can be incorporated into the seat backs, head rests or semi-recesses or in the finishing sections of the doors.