Electronic audio communication system inside a motor vehicle

Abstract

The invention consists of an electronic audio system for communicating inside a vehicle, wherein said electronic system comprises a control unit and a plurality of pairs of loudspeakers and microphones, wherein each pair is positioned in proximity to seats of said motor vehicle, and wherein each one of said pairs of loudspeakers and microphones is so positioned that the pick-up direction of the microphone is substantially perpendicular to the sound emission direction of the respective loudspeaker, and wherein the control unit is configured for inhibiting the pairs of loudspeakers and microphones located in proximity to at least one seat of the motor vehicle when safety devices comprised in the motor vehicle generate a presence signal indicating that said at least one seat is not being occupied by a passenger.

Description

[0001] TITLE : ELECTRONIC AUDIO COMMUNICATION SYSTEM INS IDE A MOTOR

[0002] VEHICLE

[0003] DESCRIPTION :

[0004] The present invention relates to an electronic audio system for communicating inside a motor vehicle .

[0005] It is known that passengers sitting in the rear seats of a car often have di f ficulty in hearing, and being heard by, passengers sitting in the front seats , especially when music or speech is being played .

[0006] In particular, sometimes the driver, in order to be heard by the rear seat passengers , will have to turn back his / her head, with adverse ef fects on drive safety .

[0007] Another problem that needs to be tackled when designing a vehicular electronic audio communication system is to avoid the so-called "Larsen ef fect" , i . e . , that phenomenon which occurs when a microphone and a loudspeaker are set too close to each other, thus triggering a sound ampli fication cycle resulting in ampli fication stage instability and annoying noise . In fact , when the sound produced by a loudspeaker is picked up by a microphone , ampli fied, and then reproduced again by the loudspeaker, a feedback cycle will be generated in which the sound will be continuously ampli fied and reproduced . This cycle will cause the sound intensity to progressively increase and undesirably produce a whistle or shrill noise .

[0008] The present invention aims at solving these and other problems by providing an electronic audio system for communicating inside a vehicle as set forth in the appended claim 1 .

[0009] The basic idea of the present invention is to employ pairs of loudspeakers and microphones , wherein each pair is positioned in proximity to a passenger seat and is so oriented that the loudspeaker and the associated microphone have their axes substantially perpendicular to each other, and wherein the loudspeaker and microphone pairs are inhibited on the basis of information about the passengers actually sitting in a motor vehicle .

[0010] Furthermore , all microphones that are not proximal to the passenger who is currently speaking will also be inhibited, along with the loudspeaker located near that passenger, which will be referred to herein as first passenger .

[0011] In order to further prevent the risk of producing an echo ef fect ( Larsen ef fect ) , at least one frequency range that might produce said echo ef fect is determined, preferably on a periodical basis ( e . g . , whenever a passenger gets in or out of the vehicle ) .

[0012] It is clear that the presence of an electronic audio communication in a motor vehicle facilitates conversation between front seat passengers and rear seat passengers , while also improving drive safety .

[0013] At the same time , the Larsen ef fect can be prevented through the adoption of innovative measures as to the spatial and geometrical positioning of microphones and loudspeakers , and through the analysis of the frequencies that might generate possible echoes .

[0014] Further advantageous features of the present invention are set out in the appended claims , which are an integral part of the present description .

[0015] These features as well as further advantages of the present invention will become more apparent in the light of the following description of some preferred embodiments thereof , one of which is shown in the annexed drawings , which are provided herein merely by way of non-limiting example , wherein :

[0016] - Fig . 1 shows a block diagram of an electronic audio communication system inside a motor vehicle according to the invention;

[0017] - Fig . 2 shows a schemati zed plan view of a motor vehicle equipped with the electronic system of Fig . 1 .

[0018] In this description, any reference to "an embodiment" will indicate that a particular configuration, structure or feature is comprised in at least one embodiment of the invention . Therefore , expressions such as " in an embodiment" and the like , which may be found in di f ferent parts of this description, will not necessarily refer to the same embodiment . Moreover, any particular configuration, structure or feature may be combined as deemed appropriate in one or more embodiments . The references below are therefore used only for simplicity' s sake , and shall not limit the protection scope or extension of the various embodiments .

[0019] With reference to Figure 1 , the following will describe an electronic system S for audio communication inside a motor vehicle according to the invention; said electronic audio system S comprises a control unit 1 ( i . e . , an electronic circuit included in the electronic communication system) that comprises a central unit 11 for processing the signals and controlling the functionality of the entire electronic audio communication system . Although not shown in the figure , memory means are also included which are necessary for the operation of said central unit . Numeral 12 designates audio output ( interface ) means connected to at least 4 loudspeakers , designated by reference numerals 21 to 24 . Numeral 13 designates audio input ( interface ) means connected to at least 4 microphones , designated by reference numerals 31 to 34 . Numeral 14 designates interface means between the outside and the electronic circuit 1 . Said interface means 14 can be used by the user of the motor vehicle for controlling and issuing commands to the electronic audio communication system inside the motor vehicle , as well as for connecting said electronic system to calibration and setup devices . Lastly, numeral 247 designates a data bus that mutually connects the central unit 11 , the audio output interface means 12 , the audio input interface means 13 and the outside interface means 14 .

[0020] In other words , the electronic system S according to the invention comprises the following components:

[0021] - the control unit 1, which comprises the audio output means 12 (which may comprise, for example, a digital-to-analog converter) , the audio input means 13 (which may comprise, for example, an analog-to-digital converter, ADC) , and processing means 11 (which may comprise, for example, a CPU, a CPLD, an FPGA, a DSP, or the like) in communication with said audio output means 12 and said audio input means 13;

[0022] - a plurality of pairs of loudspeakers 21-24 and microphones 31-34, wherein each pair is positioned in proximity to seats of the motor vehicle, wherein said loudspeakers 21,22,23,24 are in communication with said audio output means 12, and said microphones 31,32,33,34 are in communication with said audio input means 13.

[0023] When the electronic system S is in an operating condition, the processing means 11 are configured to execute the following steps :

[0024] - detecting, through at least one of said microphones 31,32,33,34, that a first passenger in the motor vehicle is beginning to speak, e.g. by executing a set of instructions implementing a speech recognition algorithm, such as a neural network trained to recognize whether a person is actually talking to another person or not (when, for example, he / she is talking to him / herself, i.e. thinking out loud) ;

[0025] - acquiring, through said audio input means 13, a first signal representing a voice of said first passenger;

[0026] - processing said first signal, thereby generating a second signal ;

[0027] - reproducing, through at least one of said loudspeakers, said second signal, wherein said at least one of said loudspeakers 21,22,23,24 is in a position closer to a second passenger, who is also sitting in the motor vehicle, than to said first passenger .

[0028] With reference to Figure 2, the following will describe a motor vehicle A comprising the electronic system S; such motor vehicle A preferably comprises four seats S1-S4, wherein SI is the front seat for the driver, S2 is the front seat for the passenger beside the driver, S4 is the rear seat on the driver side, and S3 is the rear seat on the side opposite the driver side .

[0029] The loudspeakers 21, 22, 23 and 24 are those previously mentioned herein with reference to Fig. 1. Fig. 2 shows their spatial disposition inside the motor vehicle A; in particular, the loudspeaker 21 is located on the left of the driver seat SI, the loudspeaker 22 is located on the right of the front passenger seat S2, the loudspeaker 24 is located on the left of the rear seat S4 on the driver side, and, lastly, the loudspeaker 23 is located on the right of the rear seat 23 on the side opposite the driver side.

[0030] Furthermore, the pick-up direction of each one of the four microphones 31 to 34 is substantially perpendicular to the sound emission direction of the four loudspeakers 21 to 24, and the processing means 11 of the control unit 1 are also configured for inhibiting the pairs of loudspeakers 21,22,23,24 and microphones 31,32,33,34 located in proximity to at least one seat of the motor vehicle A when safety devices comprised in the motor vehicle A generate a presence signal indicating that said at least one seat is not being occupied by a passenger. For detecting the presence signal, the control unit 1 may comprise additional input means (such as one or more GPIO port, a Bluetooth® device, a CAN-bus interface or the like) in communication with said safety devices.

[0031] In practice, the acoustic waves emitted by a loudspeaker can hardly be picked up by the associated microphone (i.e. the one within its neighbourhood) because the waves will propagate in a direction perpendicular to the microphone's pick-up capacity, and also because any microphones that may pick up sound waves generated by the loudspeakers 21-24 due to passenger absence will be inhibited ( disabled) . This will reduce the probability of occurrence of the Larsen ef fect , resulting in beneficial ef fects on safety while driving the vehicle A.

[0032] This result can be further enhanced through the use of directive microphones ( e . g . cardioid ones ) and directive loudspeakers ( the latter operating in this mode when the electronic circuit 1 reali zes that voice communication, as opposed to music reproduction, is occurring inside the motor vehicle A among the passengers thereof ) . To this end, in a preferred solution each loudspeaker may consist of a matrix of smaller loudspeakers which, in a speech condition, are driven (by using in-phase and out-of-phase signals and exploiting constructive and destructive interference ) in such a way as to adj ust their sound emission direction and cause them to emit directional sound, whereas in an entertainment condition they are driven to emit sound in a more spatial direction .

[0033] In a preferred embodiment of the invention, the four loudspeakers 21 to 24 are preferably installed in a low position in the doors of the motor vehicle A. Combined with the abovedescribed spatial position of the microphones 31 to 34 , such a position reduces the risk of generating annoying echoes known as Larsen ef fect . In fact , while the loudspeakers are arranged in the doors of the motor vehicle A in a low position ( essentially at the same height as the cushions of the seats of the motor vehicle ) , the four microphones 31 to 34 are arranged in a high position, preferably above the level of the heads of the occupants of the motor vehicle , being installed in the roof of the motor vehicle and directed toward the passenger' s head) . In other words , the loudspeakers 21 , 22 , 23 , 24 are positioned inside the motor vehicle A at di f ferent heights than the microphones 31 , 32 , 33 , 34 .

[0034] This is useful to further reduce the probability of occurrence of the Larsen ef fect and also that the driver will have to turn his / her head . Thus , positive ef fects are produced also as concerns road safety while driving the vehicle A.

[0035] In addition to the above-described spatial measures adopted in order to avoid the occurrence of the Larsen ef fect , the processing means 11 of the control unit 1 are preferably also configured for executing the following steps :

[0036] - inhibiting those microphones which are not proximal to the speaking passenger,

[0037] - inhibiting that loudspeaker which is proximal to the speaking passenger .

[0038] This is useful to reduce even further the probability of occurrence of the Larsen ef fect , thus making it also less likely that the driver will have to turn his / her head while driving the vehicle . Thus , positive ef fects are produced also as concerns road safety while driving the vehicle A.

[0039] Furthermore , an equali zer may be applied to the loudspeaker' s audio output in order to identi fy and attenuate any frequencies that might generate the Larsen ef fect . Said equali zer is preferably implemented through a set of instructions executed by the processing means 11 . This equali zer can be designed by taking into account the constitution of the motor vehicle A in which the electronic audio communication system will be installed . In fact , the accurate positioning of loudspeakers and microphones , their geometric disposition and distance , and the type of sound-absorbing materials used in the motor vehicle A are all factors that may influence the onset of the Larsen ef fect .

[0040] The following procedure can be carried out in order to configure said equali zer .

[0041] After turning on the audio system that includes the microphones and loudspeakers to be subj ected to equali zation, said equali zer can be set up by means of , for example , a set of instructions implementing an audio calibration program and which, when executed by the processing means 11 , identi fy and generate , based on the system' s audio response ( as previously determined) , a gain function that defines a gain to be applied to at least one frequency component of the input signal acquired by at least one of said microphones.

[0042] It must be pointed out that particular attention must be paid to adjusting the gain of the audio amplifier in the frequency range above 6-8 kHz, since these are the frequencies that are typically responsible for the Larsen effect.

[0043] Once the problematic (critical) frequency bands for the specific type of motor vehicle A under examination have been identified, the gain of such specific frequency bands can be reduced .

[0044] More generally, the processing means 11 of the control unit 1 are preferably also configured for executing the following steps :

[0045] - determining at least one range of critical frequencies that might produce an echo effect;

[0046] - generating an attenuation and / or cancellation of any components of the audio output signal (second signal) that fall within said range of critical frequencies, thus preventing the echo effect.

[0047] In this manner, the audio signal can be equalized to avoid the generation of the Larsen effect, thereby reducing the probability that the driver will have to turn back his / her head while driving the vehicle A. This will result in advantageous effects on safety while driving the vehicle A.

[0048] In more detail, the processing means 11 may also be configured for determining at least one range of critical frequencies that might produce an echo effect on the basis of a spatial disposition of the pairs of loudspeakers 21,22,23,24 and microphones 31,32,33,34 inside the motor vehicle A. Such an approach turns out to be particularly advantageous because it makes it possible to calibrate the system during the development of the motor vehicle A, or anyway when substantial changes are made to the passenger compartment of the vehicle A (e.g. installation of the control unit 1 along with the microphones 31-34 and, optionally, the loudspeakers 21-24 , addition or removal of a seat , etc . ) , so that the probability of occurrence of the Larsen ef fect can be further reduced, along with the probability that the driver will need to turn his / her head while driving in order to talk to the rear seat passengers . This will also result in positive ef fects on road safety while driving the vehicle A.

[0049] As an alternative to the above , the processing means 11 may also be configured for executing the following steps :

[0050] - generating an audio excitation signal with energy concentrated in at least one frequency range ;

[0051] - emitting, through at least one of said loudspeakers , said audio signal with concentrated energy;

[0052] - acquiring, through at least one of said microphones 31 , 32 , 33 , 34 , a feedback audio signal ;

[0053] - determining at least one range of critical frequencies that might produce an echo ef fect on the basis of said feedback signal .

[0054] Such an approach turns out to be particularly advantageous because it makes it possible to calibrate the system whenever a change is made to the passenger compartment of the vehicle A which results in a modi fication of its acoustic properties , e . g . when a person gets in or out , when a seat is adj usted, etc . , thus further reducing the probability of occurrence of the Larsen ef fect and also the probability that the driver will need to turn his / her head while driving in order to talk to the rear seat passengers . This will also result in positive ef fects on road safety while driving the vehicle A.

[0055] This equali zer calibration operation can be carried out periodically by the processing means 11 in real time , particularly i f the data processing speed of the latter is suf ficiently high to permit identi fying and attenuating in j ust a few milliseconds any frequencies that might potentially generate the Larsen ef fect . In this case , the transmission of the output signal to the various loudspeakers may be delayed by the time necessary for the equali zer to intervene , which will thus operate dynamically, so that driving the vehicle A will be made even safer .

[0056] Another useful measure for preventing the Larsen ef fect consists of inserting in the ampli fication chain a device producing an imperceptible "vibrato" by slightly and cyclically raising and lowering the frequencies in the whole spectrum being processed, thereby preventing the signal produced by the loudspeaker from entering the microphone with the same frequency or phase .

[0057] It is important to point out that the equali zer thus calibrated for a speci fic motor vehicle or the device producing the "vibrato" ef fect are not used when the loudspeakers are di f fusing, instead of passenger speech, sound received from the audio entertainment system .

[0058] In other words , the processing means 11 are preferably configured for generating said second signal by shi fting the frequency of said first signal , i . e . for generating the second signal by means of an operation of convolution in the time domain between the first signal ( acquired by at least one of the microphones 31-34 ) and a sinusoidal signal having a frequency equal to the frequency value , preferably in the range of 0 . 5 to 10 Hz , by which the first signal is to be shi fted in the frequency domain . This is useful to further reduce the risk of occurrence of the Larsen ef fect , while making it also less likely that the driver will need to turn his / her head while driving in order to talk to the rear seat passengers . This will also result in positive ef fects on road safety while driving the vehicle A.

[0059] It must be pointed out that the electronic measures for preventing the onset of the Larsen ef fect can be ef fectively implemented by calibrating the system speci fically for every single motor vehicle A, by programming the control unit 1 through the interface means 14 .

[0060] According to a further advantageous embodiment of the present invention, the processing means of the electronic audio system are configured for detecting the ambient noise surrounding one the microphones and are configured for applying a noise cancellation algorithm to the acquired signal captured by at least one of the microphones representing the voice of the first passenger, who starts to speak . In this way the noise around the speaking passenger is detected and cancelled before any ampli fication is applied, so that the listening experience of the remaining passengers is improved .

[0061] Further or in addition to one of the above described embodiments , the processing means are configured for detecting a high voice , crying noise , scream noise , or a high-pitched noise originated from one of the microphones and is configured to inhibit the reproduction of the aforementioned disturbing voices through at least one of the loudspeakers . According to this embodiment the mentioned disturbing voices are avoided to be reproduced as an output signal through the loudspeakers , which may in particular distract or scare the driver, causing dangerous driving manoeuvres . The detection of the high voice , crying noise , scream noise , or the high-pitched noise can be applied through setting of the corresponding frequency bands for these disturbing voices . The inhibited frequency bands are preferably one of the following : 300Hz- 600Hz , 30Hz- 150Hz , around 2 kHz or higher .

[0062] According to a further advantageous embodiment of the present invention the processing means are configured for receiving an input parameter through the interface means . The input parameter is adapted for setting the sensibility level of the detection of at least one of the microphones and / or for setting the energy level of the reproduction level of the second signal through the at least one of the loudspeakers . The input parameter considers in particular the passenger constellation, such as " FAMILY" , "BUS INESS" , "TAXI" , "TOURISTIC" , "SLEEPING" , "PHONE CALL" , " FRONT TALK" , "REAR TALK" , "CHILDREN REAR" , or the like . According to the aforementioned catch words as input parameter, the acquisition over at least one of the microphones and / or the reproduction through the at least one of the loudspeakers can be set . The setting is executed in such a way, that depending on the set parameter, the activation and / or deactivation of the at least one microphone and / or at least one loudspeaker is performed . The activation and / or deactivation is aimed to dedicate speaking and / or listening subgroups across the passengers , seated in di f ferent positions in the vehicle . The subgroups are characteri zed in particular by conversation groups in the front , in the rear or across all the passengers including or excluding the driver . Thus , a subgroup may be in particular one of the following : all of the passengers including the driver, all of the passengers including the driver, front seated passengers , rear seated passengers , rear seated passengers excluding the rear left seated passenger, rear seated passengers excluding the rear right seated passenger or the like . It is clear, that the aforementioned subgroup setting capabilities are not limited j ust to vehicle with two rows of seats , but is arbitrarily expandable to vehicles with more than two rows of seats .

[0063] Some of the possible variants of the invention have been described above , but it will be clear to those skilled in the art that other embodiments may also be implemented in practice , wherein several elements may be replaced with other technically equivalent elements . The present invention is not , therefore , limited to the above-described illustrative examples , but may be subj ect to various modi fications , improvements , or replacements of equivalent parts and elements without however departing from the basic inventive idea, as speci fied in the following claims .

Claims

CLAIMS1. Electronic audio system (S) for communicating inside a motor vehicle (A) , comprising- a control unit (1) comprising audio output means (12) , audio input means (13) , and processing means (11) in communication with said audio output means (12) and said audio input means (13) ,- a plurality of pairs of loudspeakers (21,22,23,24) and microphones (31,32,33,34) , wherein each pair is adapted to be positioned in proximity to seats (Pl, P2, P3, P4) of said motor vehicle (A) , wherein said loudspeakers (21,22,23,24) are in communication with said audio output means (12) , and said microphones (31,32,33,34) are in communication with said audio input means (13) , wherein the processing means (11) of the control unit are configured for- detecting, through at least one of said microphones (31,32,33,34) , that a first passenger in the motor vehicle is beginning a speak,- acquiring, through said audio input means (13) , a first signal representing a voice of said first passenger,- processing said first signal, thereby generating a second signal ,- reproducing, through at least one of said loudspeakers, said second signal, wherein said at least one of said loudspeakers (21,22,23,24) is in a position closer to a second passenger, who is also sitting in the motor vehicle (A) , than to said first passenger, wherein each one of said pairs of loudspeakers (21,22,23,24) and microphones (31,32,33,34) is so positioned that the pick-up direction of the microphone is substantially perpendicular to the sound emission direction of the respective loudspeaker, andwherein the processing means (11) of the control unit (1) are also configured for- inhibiting the pairs of loudspeakers (21,22,23,24) and microphones (31,32,33,34) located in proximity to at least one seat of the motor vehicle when safety devices comprised in the motor vehicle (A) generate a presence signal indicating that said at least one seat is not being occupied by a passenger .

2. Electronic system (S) according to claim 1, wherein the processing means (11) of the control unit (1) are also configured for- inhibiting those microphones which are not proximal to said first passenger,- inhibiting that loudspeaker which is proximal to said first passenger .

3. Electronic system (S) according to claim 1 or 2, wherein the processing means (11) of the control unit (1) are also configured for- determining at least one range of critical frequencies that might produce an echo effect, and- generating, on the basis of said at least one determined range of frequencies, an attenuation and / or cancellation of any components of the second signal that fall within said range of critical frequencies, thus preventing the echo effect .

4. Electronic system (S) according to claim 3, wherein the processing means (11) are configured for determining at least one range of critical frequencies that might produce an echo effect on the basis of a spatial disposition of the pairs of loudspeakers (21,22,23,24) and microphones (31,32,33,34) inside the motor vehicle (A) .

5. Electronic system (S) according to claim 3, wherein the processing means (11) are also configured for- generating an audio excitation signal with energyconcentrated in at least one frequency range,- emitting, through at least one of said loudspeakers (21,22,23,24) , said audio signal with concentrated energy,- acquiring, through at least one of said microphones (31,32,33,34) , a feedback audio signal,- determining said at least one range of critical frequencies that might produce an echo effect on the basis of said feedback signal.

6. Electronic system (S) according to any one of claims 3 to5, wherein the processing means (11) of the control unit (1) are also configured for cyclically executing the steps of determining at least one range of critical frequencies and generating an attenuation and / or cancellation of those components of the audio output signal which fall within said range of critical frequencies.

7. Electronic system (S) according to any one of claims 1 to6, wherein each loudspeaker (21,22,23,24) of a loudspeaker (21,22,23,24) and microphone (31,32,33,34) pair is positioned at a different height than the associated microphone of said pair (31,32,33,34) .

8. Electronic system (S) according to any one of claims 1 to7, wherein the processing means (11) are configured for cyclically generating said second signal by shifting the frequency of said first signal.

9. Electronic system (S) according to any one of claims 1 to8, wherein said processing means (11) are configured for detecting the ambient noise surrounding one of said microphones (31,32,33,34) and applying a noise cancellation algorithm to said first signal representing said voice of said first passenger .

10. Electronic system (S) according to any one of claims 1 to 9, wherein said processing means (11) are configured for detecting a high voice, crying noise, scream noise, or a high- pitched noise originated from one of said microphones(31,32,33,34) and to inhibit said reproduction of the same through said at least one of said loudspeakers (21,22,23,24) .

11. Electronic system (S) according to any one of claims 1 to 10, wherein said processing means (11) are configured for receiving an input parameter through interface means (14) for setting the sensibility level of said detection of said microphones (31,32,33,34) and / or for setting the energy level of said reproduction level of said second signal through said at least one of said loudspeakers (21,22,23,24) .

12. Electronic system (S) according to any one of claims 1 to 11, wherein said processing means (11) are configured for receiving an input parameter through said interface means (14) for setting at least one subgroup across predetermined passenger positions to activate and / or deactivate at least one of said microphones (31,32,33,34) and / or at least one of said loudspeakers (21,22,23,24) .

13. A vehicle equipped with one of said electronic systems (S) according to one of the claims 1 to 12.

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