WO2022189305A1

WO2022189305A1 - Vehicle warning system with feedback

Info

Publication number: WO2022189305A1
Application number: PCT/EP2022/055624
Authority: WO
Inventors: Fabian VUINE
Original assignee: Pss Belgium Nv
Priority date: 2021-03-12
Filing date: 2022-03-04
Publication date: 2022-09-15
Also published as: GB202103413D0; EP4304896A1

Abstract

The present invention relates to a method for providing inside a cabin of a motor vehicle audible feedback to a sound signal intended as a horn signal. The method comprises : - playing a first signal being a horn signal via a first loudspeaker (2) arranged for emitting the horn signal mainly away from the motor vehicle, - playing, substantially simultaneously with and in response to the horn signal, a second signal via a second loudspeaker (4) arranged for emitting the signal mainly towards the inside of the cabin.

Description

Vehicle Warning System with Feedback

Field of the invention

[0001] The present invention is generally related to the field of devices which generate external sound for a motor vehicle. To be more precise, it is related to acoustic vehicle warning systems for outputting an acoustic warning signal, in particular a horn signal.

Background of the invention

[0002] Slow driving electric vehicles produce too little noise to be noticed by pedestrians.

This clearly poses a safety issue, for example in front of schools, at pedestrian crossings or traffic lights. Legislation has been adapted to address this matter by making mandatory the generation of artificial sound. An Acoustic Vehicle Alerting System (AVAS) is designed to emit vehicle warning sounds and alert pedestrians to the presence of electric drive vehicles. These include hybrid (HEVs), plug-in hybrid (PHEVs), and full battery electric vehicles (BEVs) travelling at low speeds, especially in the lowest speed range beyond which the noise generated by rolling tires can be easily heard.

[0003] A horn intended for producing a warning signal is installed in every vehicle. Horn signals have a typical sound that is automatically recognized by people as a horn. Worldwide people have grown accustomed to how vehicle horns sound, in spite of tonal differences that may be observed between horn sound signals. Most horns use a similar principle of operation, based on a hammer knocking on a metal disk or vice versa to resonate in a specific way, hence its tonal character. The hammer or the disc itself is moved by means of electromagnetism in a fixed manner since the frequency of the hammer or disc movements is defined by an electromechanical interruption process. Direct current from the vehicle battery, e.g. a 12V battery, is fed into a coil. The hammer moves towards the disc or vice versa. By moving forward, the contact with the battery is interrupted and after hitting the disc or the hammer the contact is restored.

[0004] The monotonous stimulation of a resonating object brings forward a recognizable alarming tone, albeit with a tonal character defined by the frequency of excitation and by the characteristics of the resonating object. Typically, a single horn produces a spectrum in which a low frequency component is clearly present (between 300Hz and 500Hz) combined with a louder high frequency component (around 2.5 kHz) amongst other less pronounced tones.

[0005] Due to this working principle and the positioning of a conventional car horn the driver can easily hear the horn during operation. However, the horn sound is partially muffled by the cabin insulation as the horn is mounted outside the vehicle cabin. This effect has been increased in recent years as acoustic car insulation has evolved to yield enhanced comfort. [0006] In particular in hybrid and electric vehicles there is a trend to implement a loudspeaker in the exterior of the vehicle to provide the above-mentioned functionalities like e.g. generating vehicle warning sounds to alert pedestrians. On top of that the external loudspeaker can also be used to play a suitable signal to mimic the traditional horn function. The external loudspeaker is typically positioned in such a way that it primarily emits the sound signal towards the outside of the vehicle. As the external loudspeaker is mainly used for pedestrian warning sounds at low speeds, such solution built-in in the exterior side of the vehicle is preferred as it decreases the artificial warning sound towards the inside of the vehicle cabin. Having the main sound signal radiation towards the outside front of the vehicle is further preferred as it directs the sound radiation towards the other road users to be warned and decreases overall noise pollution, especially in cities and during the night compared to a traditional horn signal.

[0007] Hence, due to the different working principle and mounting position the horn sound inside the vehicle cabin is substantially more muffled than that of a traditional vehicle horn. Still, user feedback is essential for operation, especially in dangerous situations when vehicle horns are typically used.

[0008] Moreover, it may be expected that signals emitted by the external loudspeaker in the future are no longer designed just to mimic the sound of a conventional vehicle horn signal. Rather, car manufacturers will incorporate different types of warning signals (e.g. a "soft horn" not to startle close by pedestrians) which may be even harder to hear by the driver on the inside of the vehicle. [0009] An example is provided to illustrate the problem at hand by means of third octave frequency band spectra. In Fig.l the third octave frequency band spectra are shown measured at 7 meter in front of a car when a traditional car horn is played and when a loudspeaker mounted in the exterior of the vehicle (an 'external' loudspeaker) plays a horn-like signal, for example taken from a sound signal library stored in the vehicle. Both the loudspeaker emitting the traditional car horn signal and the external loudspeaker radiate strong fundamental components in the frequency bands centered around 400 and 500Hz, with the external loudspeaker being approximately lOdB louder. The harmonics between 800Hz and 6.3kHz are somewhat different but on similar levels, with the external loudspeaker having stronger radiation in the 1.6kHz band. The overall A-weighted Sound Pressure Level (SPL) is on-par with 89.4dBA for the car horn signal and 90.2dBA for the loudspeaker, respectively. Both measurements so comply with the legal requirement of obtaining at least a level of 87.4 dBA in the above sketched measurement conditions.

[0010] Fig.2 illustrates two spectra measured at the position of the driver when emitting via a conventional car horn and via a loudspeaker mounted in the exterior side of the vehicle, respectively. The same signal is used as in Fig.l. The signal was designed to have strong fundamental components in order to achieve easy audibility inside the car cabin. At this measurement position the external loudspeaker is substantially quieter, approximately 5dB for the fundamental frequencies and more than lOdB on average for the harmonics. The sound is strongly muffled and barely audible during fast driving or in case of loud outside conditions, e.g. heavy rain. If the applied signal was to have the same level as a traditional car horn signal in 7m - as would be preferred - at the driver seat, the 400 and 500Hz band levels would decrease a further lOdB and user feedback is not guaranteed under all conditions.

[0011] Hence, there is a need for a warning system comprising a loudspeaker in the exterior side of the vehicle to emit a horn signal like sound signal while allowing for sufficient feedback to the driver in the vehicle cabin.

Summary of the invention

[0012] It is an object of embodiments of the present invention to provide for an audible warning system for a motor vehicle that is capable of providing feedback to the driver when a horn signal is emitted away from the vehicle. It is also an object to provide a motor vehicle wherein such an audible warning system is installed. It is a further object to provide a method for ensuring audible feedback inside a cabin of a motor vehicle when a horn signal is emitted away from the vehicle.

[0013] The above objective is accomplished by the solution according to the present invention.

[0014] In a first aspect the invention relates to a method for providing inside a cabin of a motor vehicle audible feedback to a sound signal intended as a horn signal. The method comprises :

- playing a first signal being the horn signal via a first loudspeaker arranged for emitting the horn signal mainly away from the motor vehicle,

- playing, substantially simultaneously with and in response to the horn signal, a second signal via a second loudspeaker arranged for emitting the second signal mainly towards the inside of the cabin.

[0015] The proposed solution indeed allows for providing feedback to a person inside the vehicle, in the first place the driver, when a sound signal is played that is intended as an audible warning signal, i.e. a horn signal. This horn signal is being played via a first loudspeaker that emits the horn signal mainly towards the surroundings of the vehicle, i.e. away from the vehicle. Usually the horn signal is played when an acoustic warning function in the vehicle is triggered. This may be done automatically and decided by a vehicle computer or it may be done by the driver. The first loudspeaker may for example be provided in an exterior side of the vehicle. Via a second loudspeaker so positioned that it emits sound mainly towards the inside of the vehicle cabin, a second signal is played simultaneously or more or less simultaneously with said horn signal. The second signal thus provides feedback to the driver.

[0016] In some embodiments the second loudspeaker is used only for emitting the second signal. In other embodiments the second loudspeaker provided inside the cabin of the motor vehicle is also used to provide music and/or speech playback. In that case the second loudspeaker may be part of an entertainment system or internal audio system.

[0017] In preferred embodiments of the invention the second signal is a signal related to the audible warning signal. The second signal may then be a scaled version of the horn signal emitted via the first loudspeaker. Alternatively, the second signal may be a filtered version of the horn signal. [0018] Preferably the horn signal is played when triggered by a person in the motor vehicle, typically the driver.

[0019] In another aspect the invention relates to an audible warning system for a motor vehicle, comprising a first loudspeaker arranged for emitting a first signal intended as a horn signal mainly away from said motor vehicle. The audible warning system is characterised in that it comprises a second loudspeaker arranged for emitting, substantially simultaneously with and in response to the horn signal, a second signal mainly towards the inside of the motor vehicle cabin.

[0020] In some embodiments the audible warning system comprises a signal generator for generating the audible warning signal.

[0021] In embodiments of the invention the audible warning system comprises a memory to store the horn signal. In certain embodiments the warning system is arranged to select the horn signal from a library of possible horn signals stored in the memory.

[0022] In one embodiment the audible warning system is arranged to interrupt a further signal which is being emitted via the second loudspeaker when the horn signal is to be emitted.

[0023] In another embodiment the audible warning system is arranged to mix a further signal being emitted via the second loudspeaker with the horn signal or with a version of that horn signal when the horn signal is to be emitted.

[0024] Advantageously, the audible warning system is arranged to interrupt a warning signal being emitted via the first loudspeaker, e.g. a sound signal to alert pedestrians, when the horn signal is to be emitted.

[0025] In one embodiment the audible warning system is arranged to adjust at least one parameter of the second signal depending on whether or not at least one other signal is being emitted via the second loudspeaker.

[0026] In a further aspect the invention relates to a motor vehicle comprising an audible warning system as previously described. [0027] In some embodiments the motor vehicle comprises a driver seat provided with a headrest and the second loudspeaker is integrated in said headrest.

[0028] For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

[0029] The above and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

Brief description of the drawings

[0030] The invention will now be described further, by way of example, with reference to the accompanying drawings, wherein like reference numerals refer to like elements in the various figures. [0031] Fig.l illustrates third octave frequency band spectra measured at 7m distance on

1.1m height frontal of the car when a traditional car horn is blown and emitted by an external loudspeaker when a horn-like warning signal from a library is applied.

[0032] Fig.2 illustrates third octave frequency band spectra measured at the driver seat at the centre of the front surface of the headrest when a traditional car horn is blown and emitted by an external loudspeaker when a horn-like warning signal from a library is applied playing the same signal as corresponding to Fig.l

[0033] Fig.3 illustrates schematically the position of a first and a second loudspeaker according to an embodiment of the audible warning system of the invention.

[0034] Fig.4 illustrates a possible positioning of a first and a second loudspeaker in a door of the motor vehicle.

[0035] Fig.5 illustrates schematically the audio signal over time for the first, external, and second, internal, loudspeaker before, during and after the horn function is used.

[0036] Fig.6 illustrates the third octave frequency band spectrum measured at the driver seat at the centre of the front surface of the headrest when a traditional car horn is blown. It also shows the third octave frequency band spectrum at the same position when the external loudspeaker plays the same horn-like warning signal from a library as corresponding to Fig.l while the internal loudspeakers play a filtered version of said signal. Detailed description of illustrative embodiments

[0037] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. [0038] Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0039] It is to be noticed that the term "comprising", used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0040] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments. [0041] Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention. [0042] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0043] It should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re defined herein to be restricted to include any specific characteristics of the features or aspects of the invention with which that terminology is associated.

[0044] In the description provided herein, numerous specific details are set forth. Flowever, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0045] The present invention proposes a solution to provide inside a cabin of a motor vehicle audible feedback to an emitted sound signal that is intended as a horn signal. Key element of the solution is a loudspeaker that emits mainly to the inside of the cabin and substantially simultaneously with the horn signal, a second signal that may be related to that horn signal. In one aspect the invention relates to an audible warning system comprising such a loudspeaker. In another aspect the invention relates to a method for providing audible feedback inside a cabin of a motor vehicle, wherein such a loudspeaker is applied.

[0046] An audible warning system according to the present invention comprises at least two loudspeakers. As illustrated in Fig.3, a first loudspeaker 2 is positioned in the motor vehicle so that the audible warning signal is mainly emitted away from the vehicle. In preferred embodiments the first loudspeaker 2 is placed entirely in the so called wet zone of the motor vehicle, i.e. the area of the vehicle which is not climatized, corresponding the area outside the vehicle cabin. Alternatively, the first loudspeaker 2 may be positioned with the rear cavity of the loudspeaker mounted in the dry zone of the motor vehicle but having the acoustically open front surface mounted in the wet zone and radiating sound towards the outside of the vehicle.

[0047] As commonly known in the art, a loudspeaker has a membrane (also often called diaphragm) having a front surface facing in a forward direction for producing sound to be radiated outwardly from the loudspeaker in the forward direction and a back surface facing in a backward direction. The membrane is for example circular. More in general, one can say that in the present invention the first loudspeaker has a surface of the loudspeaker membrane connected in a so called wet zone of the vehicle, as also illustrated in Fig.4. A first loudspeaker 2 is positioned to radiate mainly towards the outside of the vehicle.

[0048] The audible warning signal is in this invention a sound signal to mimic a horn signal.

Alternatively, it can be a pedestrian alerting sound signal, i.e. a sound that indicates to pedestrians that a motor vehicle is approaching or another type of warning signal.

[0049] The present invention proposes to use a second loudspeaker 4 so positioned that it mainly emits towards the inside of the vehicle cabin. See Fig.3. The second loudspeaker can for example be a loudspeaker of an entertainment system for speech and music feedback present in the vehicle or another loudspeaker that is already provided in the vehicle cabin. In some embodiments the second loudspeaker can be a loudspeaker especially dedicated to providing feedback. In some embodiments a plurality of second loudspeakers can be comprised in the audible warning system. [0050] The second loudspeaker is preferably positioned inside the cabin of the motor vehicle, i.e. in the so-called dry zone of the vehicle. In some embodiments the second loudspeaker is mounted for example in a door of the vehicle and so positioned that it mainly radiates towards the inside of the vehicle cabin as illustrated in Fig.4.

[0051] Via the second loudspeaker is played a second signal. In the embodiments of the invention the second signal is related to the horn signal emitted via the first loudspeaker. Such a signal related to the horn signal can be derived in many different ways. In some embodiments the signal is merely a scaled version of the signal emitted via external loudspeaker of the warning system. As already mentioned, with external loudspeaker is meant a loudspeaker mounted in the exterior of the vehicle. The internal signal used as feedback signal can for example be a version of the external horn signal that was fed to the respective loudspeakers, but scaled in voltage compared to the external horn signal. In some embodiments the second signal can be a filtered version of the external horn signal. For example, the internal loudspeaker can play a low-pass filtered version of the external signal to match the user expectation of what a traditional car horn sounds like on the inside of the vehicle.

[0052] In other embodiments the second signal can be a signal that is not derived from one or more characteristics of the horn signal being played, but a signal that is selected or chosen by a user to be played when the horn button is pushed. Manufacturers may indeed provide a signal or a set of selectable signals to provide feedback whereby each signal is manufacturer specific. The signal is then only 'related' to the horn signal in the sense that both signals are played at substantially the same moment in time and that one signal is played in reaction to playing the other signal.

[0053] The second signal may be different depending on the warning signal it provides feedback on. For example, if the second signal can not only be emitted response to an audible warning signal intended as a horn signal, but also in response to for example a pedestrian alerting sound, the second signal produced in this latter case may sound different.

[0054] Preferably, the audible warning system plays the first signal, i.e. the audible warning signal, when it is triggered by a person, typically the driver, as is the case with a conventional car horn.

[0055] The signal providing feedback to the driver (hence, the second signal) is played substantially simultaneously with and in response to the sound signal intended as the horn signal (the first signal). As the skilled person will readily understand, it is not strictly needed that the second signal is heard exactly at the same time as the horn signal in order to be recognizable as a signal providing feedback when the horn signal is emitted. A certain latency of e.g. less than 500 ms, is still acceptable to experience the signal as feedback to the horn signal being played. Preferably the latency is less than 50 ms, more preferably less than 5 ms. On the other hand, if the second signal comes e.g. a second or more later than the horn signal, it will not be perceived anymore by the user as feedback to the horn signal.

[0056] In some embodiments the audible warning signal, i.e. the horn sound, is generated in real-time. The audible warning system then comprises a signal generator to produce the warning signal. In other embodiments the horn signal is taken (selected) from a memory provided in the audible warning system, where one or more possible sound signals that are candidate to be played, are stored. The generation or selection of the audible warning system may depend on the state of the vehicle. For example, the vehicle speed, acceleration, driving direction, time of the day, the surrounding sound level inside and/or outside the vehicle can be a parameter, but also e.g. whether or not the entertainment system, if present, is in use.

[0057] The sound signal intended to mimic a horn signal may be designed to be recognizable as such when output by said first loudspeaker of the warning system. Certain specifications of the horn signal imposed by legislation need to be met. One example of a standard wherein such specifications are adopted, is the European ECE-28 standard. The horn needs to be homologated both at vehicle level and at device level. At device level the power sum of A-weighted 2 kHz, 2.5 kHz and 3.15 kHz third octave frequency bands of the generated horn signal should be at least 105 dB sound pressure level (SPL), measured in free field conditions and with a microphone on-axis at 2 m from the device under test. At vehicle level the A-weighted sound pressure level should be at least 87 dB(A), measured in half space free field outside and on-axis at a distance of 7m from the vehicle, with the microphone at least 0.5 m above the ground. Further, also the design of an audible vehicle warning system is subject to a set of legal requirements. [0058] In some embodiments of the invention the audible warning system is arranged to interrupt a signal being emitted via the second loudspeaker (4), e.g. a music or speech signal, when the horn signal is to be emitted. Fig.5 illustrates, by way of example, a case where the internal loudspeaker of the entertainment system is playing music, e.g. from FM radio. In the event of a user, e.g. the driver, pushing the horn button the music signal is interrupted and replaced by the same warning signal as the external loudspeaker from a sound library for the duration of the horn event, albeit in a scaled version at lower voltage. In the example of Fig.5 the sound signal that mimics the horn signal is taken from a library. As can be seen, the feedback signal is played simultaneously with the horn signal being emitted away from the vehicle. After the feedback signal has been played, the music signal continues as before.

[0059] In other embodiments, the music signal is only decreased in level and the horn signal is mixed into it or the music signal is low-pass filtered and the warning signal used as feedback signal only contains the horn harmonics. Any combination of adding or modifying the signals is possible, however, the internal and external warning sounds will always be substantially time-aligned, meaning they basically start and stop at the same time during the horn event.

[0060] The external loudspeaker may be playing a pedestrian alerting sound at low levels due to the low speed of the vehicle. Preferably the audible warning system is also arranged to interrupt the external loudspeaker in case suddenly a horn signal is to be emitted and replace the audio stream output by the loudspeaker by the horn signal.

[0061] In case the second loudspeaker is dedicated to emitting a feedback signal when the horn button is pushed, this loudspeaker is always available. In case the second loudspeaker is a loudspeaker that is part of for example an entertainment system, the latter is so arranged that the feedback signal can also be played by the speaker when the entertainment system is switched off. In some embodiments the feedback signal may be different depending on whether the entertainment system is switched on or off or on the level at which it is playing or even on what content it is playing, e.g. depending on the current RMS level of the music signal. The feedback signal is adjusted to be always clearly audible but not startle the driver either.

[0062] The effect of providing a second loudspeaker to emit a feedback signal inside the vehicle cabin is illustrated in Fig.6. Fig.6 shows the l/3^rd octave band spectrum measured at the driver seat with the external first loudspeaker radiating the same signal as before but an internal second loudspeaker being active and radiating a low-pass filtered version of the externally used signal at low level. The audibility is substantially increased and the user feedback is guaranteed.

[0063] In another aspect the invention is related to a motor vehicle comprising an audible warning system as previously described. [0064] In some embodiment the motor vehicle is equipped with one or more seats having a headrest. Preferably the second loudspeaker is then positioned in a headrest, for example the headrest of a driver seat. [0065] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. The invention is not limited to the disclosed embodiments. [0066] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. Method for providing inside a cabin of a motor vehicle audible feedback to a sound signal intended as a horn signal, the method comprising :

- playing a first signal being a horn signal via a first loudspeaker (2) arranged for emitting said horn signal mainly away from said motor vehicle,

- playing, substantially simultaneously with and in response to said horn signal, a second signal via a second loudspeaker (4) arranged for emitting said second signal mainly towards the inside of said cabin.

2. Method for providing audible feedback as in claim 1, wherein said second loudspeaker (4) is dedicated to emitting said second signal.

3. Method for providing audible feedback as in claim 1, wherein said second loudspeaker (4) provided inside said cabin is also used to provide music and/or speech playback.

4. Method for providing audible feedback as in any of the previous claims, wherein said second signal is a scaled version of said horn signal.

5. Method for providing audible feedback as in any of the previous claims, wherein said second signal is a filtered version of said horn signal.

6. Method for providing audible feedback as in any of the previous claims, wherein said horn signal is played when triggered by a person in said motor vehicle.

7. Audible warning system for a motor vehicle, comprising a first loudspeaker (2) arranged for emitting a first signal intended as an horn signal mainly away from said motor vehicle, characterised in that said audible warning system comprises a second loudspeaker (4) arranged for emitting, substantially simultaneously with and in response to said horn signal, a second signal mainly towards the inside of said motor vehicle.

8. Audible warning system as in claim 7, comprising a signal generator for generating said horn signal.

9. Audible warning system as in claim 7, comprising a memory to store said horn signal.

10. Audible warning system as in claim 9, arranged for selecting said horn signal from a library of possible horn signals stored in said memory.

11. Audible warning system as in any of claims 7 to 10, arranged to interrupt a further signal being emitted via said second loudspeaker (4) when said horn signal is to be emitted.

12. Audible warning system as in any of claims 7 to 10, arranged to mix a further signal being emitted via said second loudspeaker (4) with said horn signal or a version thereof when said horn signal is to be emitted.

13. Audible warning system as in any of claims 7 to 12, arranged to interrupt a warning signal being emitted via said first loudspeaker (2) when said horn signal is to be emitted.

14. Audible warning system as in any of claims 7 to 13, arranged to adjust at least one parameter of said signal related to said horn signal depending on whether or not at least one other signal is being emitted via said second loudspeaker (4).

15. Motor vehicle comprising an audible warning system as in any of claims 7 to 14.

16. Motor vehicle as in claim 15, wherein said second loudspeaker (4) is positioned in a headrest of a driver seat.