News Column

Patent Application Titled "Method and Device for Synthetic Generation of an Acoustic Signal" Published Online

July 3, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventor Klier, Markus (Kueps, DE), filed on December 10, 2013, was made available online on June 19, 2014.

The assignee for this patent application is Lear Corporation.

Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to a method and a device for synthetic generation of an acoustic signal, e.g. in a vehicle. A control signal for controlling a motor or a detection signal, which detects the engine speed for example, is fed as input signal to a device for generating the acoustic signal, wherein at least one electromechanical transducer generates the acoustic signal by means of an electrical transducer excitation signal. To this end, an electromechanical transducer can be a loudspeaker or an exciter which generates sound waves at components of a vehicle.

"The present invention relates to a method and a device for synthetic generation of an acoustic signal, e.g. in a vehicle. A control signal for controlling a motor or a detection signal, which detects the engine speed for example, is fed as input signal to a device for generating the acoustic signal, wherein at least one electromechanical transducer generates the acoustic signal by means of an electrical transducer excitation signal. To this end, an electromechanical transducer can be a loudspeaker or an exciter which generates sound waves at components of a vehicle.

"It is already well known to artificially generate engine sounds of an internal combustion engine or engine in general in a motor vehicle or to amplify the engine sounds of an internal combustion engine through various devices and methods and to change their tone in a particular manner. This is often accomplished using a particular structural design of the components of the engine or exhaust gas system, wherein it is moreover also possible to integrate electromechanical transducers (exciters or loudspeakers) in the exhaust gas system of a motor vehicle having an internal combustion engine for example in order to adapt the sound waves naturally generated by the internal combustion engine to a desired sound through sound waves generated by the exciter or loudspeaker.

"It is furthermore well known to equip electric vehicles or hybrid vehicles that can often be operated only by means of an electric motor or also in electric mode with a sound that resembles that of an internal combustion engine. On the one hand, this should increase the purchase and acceptance of these types of vehicles by customers and also increase safety for other road users, such as pedestrians or bicyclists, who are accustomed to motor vehicles having a typical engine sound which thereby also warns them about this motor vehicle (e.g. when crossing a street).

"However, the difficulty lies in generating an engine sound that sounds as natural as possible and corresponds to the engine sound of a conventional motor vehicle having an internal combustion engine without sounding monotone. Devices known in the art for generating artificial engine sounds often sound synthetic.

"A method for synthetic generation of engine sounds, especially of an internal combustion engine, in which a sequence of successively generated signal sequence sections of particular sequence time intervals form a transducer excitation signal is known from DE 10 2007 055 477 A1. To this end, the engine sounds are formed from the transducer excitation signal. A sequence of successively generated signal sequence sections having particular sequence time intervals form the transducer excitation signal, wherein each signal sequence section consists of successive signal segments as signal oscillations of particular sequence time intervals, and wherein the sum of the sequence time intervals of the signal segments contained in a signal sequence section determines the sequence time interval of the assigned signal sequence section and at least two signal segments in a signal sequence section are unequal in regard to their segment time intervals and/or segment amplitudes. In the method described in DE 10 2007 055 477 A1, the transducer excitation signal is nevertheless calculated as a function of the number of cylinders of an internal combustion engine to be imitated.

"DE 10 2005 012 463 B3 describes a method for generating an engine sound of a motor vehicle having an additional sound generated by an actuator and a device for carrying out the method, wherein in a data memory of a control unit for the generation, there is stored an engine characteristic map in which level values evaluated through boundary conditions are stored at engine speed nodes, these level values being stored as multiples of half the engine speed for defined engine speeds and their assigned oscillations and orders. The stored level values corresponding to the current speed signal and therefore to the current engine speed and its higher orders are then read from the data memory and transmitted to an arithmetic unit of the control unit, wherein an actuator excitation signal as a continuous time signal in the manner of a harmonic series is calculated from the level values and the actuator excitation signal is formed therefrom. The actuator excitation signal is then outputted via a power amplifier to the actuator as an electric actuator signal, wherein the actuator converts the electric actuator signal into a vibratory force in the manner of an electrodynamic vibrator.

"DE 10 2010 043 973 A1 discloses the generation of a sound for a motor vehicle driven by an electric motor, wherein a control signal for an electric motor or for the electric motor's power electronics is generated, the control signal having a modulation for sound generation and the control signal controlling the electric motor, wherein the modulation in the electric motor generates vibrations which produce the sound.

"Furthermore known from the state of the art are methods and devices in which, proceeding from a vehicle-specific parameter (rotary frequency, speed, engaged gear, etc.), a sound assigned to this operating state is read from a memory and outputted through a loudspeaker or exciter.

"A disadvantage of the methods and devices known from the state of the art, however, is that they cannot approximately generate the natural sound of an internal combustion engine, above all because they generate strictly periodic signals and sounds or generate signals and sounds that have repeating components. This also applies to DE 10 2007 055 477 A1, which indeed makes use of different segment time intervals and/or segment amplitudes for two signal segments within one signal sequence section, but severely limits the number of signal sequence sections and number of signal segments in the signal sequence sections, thereby again producing very artificially sounding sounds.

"It is therefore the objective of the present invention to present a method and a device in which an acoustic signal is synthetically generated, wherein the generated acoustic signal is to sound very natural and no complex calculations need to be made.

"The objective is accomplished by a method having the characteristics stated in Claim 1 and by a device having the characteristics stated in Claim 16.

"Advantageous modifications are disclosed in detail in the dependent claims."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventor's summary information for this patent application: "The method for synthetic generation of an acoustic signal in a vehicle, proceeding from a control signal for controlling a motor or proceeding from a detection signal, wherein the control signal or the detection signal is fed as input signal to a device for generating the acoustic signal and at least one electromechanical transducer generates the acoustic signal by means of an electrical transducer excitation signal, features the following steps: transformation of the control signal or the detection signal into a corresponding digital input signal by a mapping function. calculating an address and an address increment from the digital input signal with the aid of at least one vehicle-specific parameter, wherein the at least one vehicle-specific parameter is used for frequency and/or phase modulation. readout of data corresponding to the calculated address from a memory by a modulo operation in which for each of a multiplicity of addresses there is stored a multiplicity of acoustic signals having small frequency and/or amplitude differences, wherein the acoustic signals assigned to one address are selected randomly and as a function of the at least one vehicle-specific parameter and are integrated into one digital output signal, wherein the acoustic signals are divided into groups and/or have a specific weighting and the acoustic signals are selected from particular groups or from acoustic signals having a particular specific weighting when defined values formed from at least one vehicle-specific parameter are exceeded or undershot, and the selected acoustic signals compose a particular portion of the digital output signal formed by the acoustic signals. conversion of the integrated digital output signal into an analog output signal and feeding of the analog output signal as a transducer excitation signal to at least one electromechanical transducer.

"The method is characterized in that in that in one operating sate of a vehicle, random acoustic signals are read from a memory and integrated into one digital output signal instead of reading and repeatedly outputting one acoustic signal (e.g. a 'sound' or a 'sound file') from a memory in a particular operating state of a vehicle as long as this operating state is maintained. In addition, the selection is carried out encompassing acoustic signals as a function of vehicle-specific parameters or one vehicle-specific parameter on the basis of the weighting of individual acoustic signals or on the basis of the weighting of individual groups. This occurs in that a particular operating state of a vehicle arises during acceleration of the vehicle, for example, and a particular address is therefore assigned to the digital input signal, wherein this operating state can also appear during braking of a vehicle, but because of the position of the accelerator or brake pedal (or on account of other vehicle-specific values or parameters) the acoustic signals will be increasingly read and played back from this one address or played back more frequently than the other acoustic signals assigned to this address. A digital output signal, which consists of acoustic signals and sounds substantially more natural, is thereby generated. Thus in one case, all of the acoustic signals assigned to one address can be randomly selected with the same probability, but wherein the randomness can also relate only to individual groups or categories of stored, weighted acoustic signals, wherein particular acoustic signals can then be selected more often than others. Moreover, a multiplicity of these types of acoustic signals assigned to one address can be stored in a memory, thereby making it relatively improbable that one acoustic signal will be selected twice during the selection of one address on the basis of one operating state. But particular rules which further define the selection of the individual acoustic signals can also be applied in the method (e.g. an acoustic signal can be called upon to form the digital output signal a second time only if at least two other different acoustic signals have been selected after the first selection).

"Moreover, the selection and the playback or integration into one digital output signal is affected based on the vehicle-specific parameters. This occurs on the basis of the groups which have particular acoustic signals or on the basis of individual acoustic signals, wherein their weighting decreases or increases. To this end the vehicle-specific parameters determine the selection of an address on one hand and then also determine the frequency at which individual acoustic signals assigned to one address are selected on the other hand. This produces a composition of a digital output signal which is/sounds very similar to natural sounds.

"Thus acoustic signals which correspond to an engine sound with different ignition behaviors can also be assigned to one address for example. These different ignition behaviors, which may also differ only slightly, will then be taken into consideration in the random playback.

"The integrated digital output signal and/or the analog output signal can also be amplified, in another method step.

"Moreover the acoustic signals can also be band-limited, wherein the band limiting can also occur for the digital output signal generated or integrated from the acoustic signals. Band limiting can be determined on the basis of the following formula, which is required to observe the Nyquist criterion:

"f.sub.Signalp2.ltoreq.f.sub.S

"f.sub.Signal: frequency of the input signal

"p: factor that indicates the frequency change

"f.sub.S: sampling frequency

"where f.sub.signal is the frequency of the input signal, p is a factor which indicates the frequency change and f.sub.S is the sampling rate frequency or sampling frequency or sampling rate.

"Processing of the digital input signal can also be carried out in a plurality of parallel processing paths, wherein the integrated digital output signals or the analog output signals are subsequently mixed and integrated.

"To this end, the digital input signal, which is generated from a transformation of the frequency of the control signal or the detection signal, is processed in parallel processing steps, wherein a there occurs a parallel calculation of an address and an address increment, a parallel readout of data corresponding to the calculated address and an integration of the acoustic signals.

"The processed output signals which lie below an audible threshold due to amplitude modulation cannot be calculated in the method, wherein they are set to '0'. This can occur for example if the acoustic output is inaudibly faint or very faint due to the digital output signal or analog output signal. This enables the computation effort for the processing to be further reduced.

"After the readout of the address from the memory and the integration of the digital output signal, it is possible to carry out another processing step in which the integrated digital output signal is filtered (by IIR and FIR filters for example) as a function of the digital input signal and subjected to an amplitude, frequency and/or phase modulation as a function of the vehicle-specific parameters. This allows sounds that are more natural to be generated, since the acoustic signals outputted by the electromechanical transducer or the sounds outputted by the electromechanical transducer do not contain any repeating signal forms or acoustic signal parts.

"Synthetically generated sounds or sound components can be mixed with the signals during signal processing, wherein the synthetically generated sounds or sound components can be generated from another arrangement for the signal generation. To this end, synthetically generated sounds or sound components can continue to be stored in the memory and, after the generation of a digital output signal, be mixed with the digital output signal. It is thus possible to store sounds which are mixed with the integrated digital output signals during full braking or when the accelerator is completely actuated.

"Event-specific sounds, which are assigned to a vehicle-specific event, can also be mixed with the analog output signal and/or with the digital output signal if a corresponding vehicle-specific event occurs. For example, vehicle-specific events can be engaging a gear, actuating or activating or deactivating devices in a vehicle, etc.

"The vehicle-specific parameters can comprise the rotary frequency and/or the load of an electric motor, of an internal combustion engine, of a transmission and/or of other components of a vehicle and/or the speed of a vehicle. Moreover, the vehicle-specific parameters can also be the number of cylinders of an internal combustion engine, temperatures in a vehicle or the outdoor temperature as well as other parameters and influences that act upon the vehicle.

"It is furthermore possible to carry out an interpolation for the acoustic signals stored in the memory as a function of parts of the address index. Processing and/or access can therefore be simplified and accelerated.

"The conversion of the control signal or detection signal into the digital input signal can be carried out using a transformation table.

"For an analog control or detection signal, a transformation of the frequency of the analog control signal or detection signal can also occur.

"The control signal or detection signal can be present both as digital and as analog. The control signal can thus be formed from an engine sound of an internal combustion engine. In further developments, the control signal or the detection signal can also be data which are obtained via the CAN bus (digital) or for example from a Hall-effect sensor of a flywheel or from an engine speed sensor (analog). The transformation of the frequency of an analog control signal into a corresponding digital control signal can be accomplished for example in that a signal for an electric motor having a rotary frequency of zero is transformed into a frequency which corresponds to the idle speed frequency of an internal combustion engine.

"It is moreover possible to calculate a 'virtual transmission' from the vehicle-specific parameters rotary frequency (e.g. of the wheels or drive shaft of an electric vehicle), load (such as the load of an electric motor) and speed of the electric vehicle, wherein the engine speed of an internal combustion engine (hybrid/electric vehicle) which is inactive or not present in the vehicle can be calculated on the basis of the above vehicle-specific parameters. Furthermore, if transformation ratios are stored in a memory, it is then possible to calculate other engine speeds of an inactive or non-present internal combustion engine. It is thus possible to calculate engine speeds of an internal combustion engine and use them for the synthetic generation of an acoustic signal, wherein the vehicle does not have an internal combustion engine or the internal combustion engine is inactive (e.g. serial hybrid vehicle in which the internal combustion engine essentially has the same engine speed).

"Moreover when the defined values are exceeded or undershot, the acoustic signals from particular groups and/or the acoustic signals having a particular specific weighting can increasingly be selected over acoustic signals from other groups or acoustic signals having another weighting and be integrated into the digital output signal. In this connection, 'increasingly' means that a division can occur in which a particular portion is preferably selected on the basis of the vehicle-specific parameters and the remaining part of the acoustic signals is randomly put together from the other acoustic signals stored in the address.

"The invention furthermore relates to a device for synthetic generation of an acoustic signal, proceeding from a control signal for controlling a motor or proceeding from a detection signal, wherein the control signal or the detection signal is fed as input signal to the device for generating the acoustic signal and wherein at least one electromechanical transducer generates the acoustic signal by means of an electromechanical transducer excitation signal.

"A device of this type demonstrates a first transformation unit in which the control signal or the detection signal is converted into a digital input signal. Moreover, the device demonstrates a calculation unit in which an address and an address increment are calculated from the digital input signal with the aid of at least one vehicle-specific parameter, wherein the at least one vehicle-specific parameter is used for frequency and/or phase modulation. The device furthermore comprises a memory unit within which for a multiplicity of addresses there are stored a multiplicity of data which comprise the acoustic signals having small frequency and/or amplitude differences, and a selection unit which randomly and as a function of the at least one vehicle-specific parameter selects and integrates into one digital output signal the acoustic signals assigned to one address. To this end, the acoustic signals are divided into groups within the memory unit and/or have a specific weighting and the acoustic signals from particular groups or acoustic signals having a particular specific weighting are selected when defined values which are formed from at least one vehicle-specific parameter are exceeded or undershot. These then form a larger portion of the digital output signal formed by the acoustic signals. The device finally comprises a second transformation unit in which integrated digital output signals are converted into an analog output signal, wherein the device is designed to carry out one of the methods described above.

"A device can yet demonstrate at least one amplifier, a signal combiner and/or at least one processing unit in which the vehicle-specific parameters, the digital input signal and/or synthetic sounds can be mixed and integrated with the output signal or digital output signal.

"To this end, a transformation of the frequency of an analog control signal or of an analog detection signal into a digital input signal can take place in the first transformation unit.

"To this end, electromechanical transducers of the device can be a loudspeaker or an exciter which introduces sound waves into components of the vehicle for generation of sounds.

"The acoustic signals assigned to one address can differ according to the driving situation and can be stored into a memory accordingly.

"Further advantages and characteristics as well as embodiments of the invention arise from the figure which is illustrated in the drawing and depicts one embodiment of the invention for sake of example. To this end, the illustrated embodiment is not to be understood as limiting and serves merely to describe the invention.

"Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is diagram for illustrating the method."

For more information, see this patent application: Klier, Markus. Method and Device for Synthetic Generation of an Acoustic Signal. Filed December 10, 2013 and posted June 19, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3975&p=80&f=G&l=50&d=PG01&S1=20140612.PD.&OS=PD/20140612&RS=PD/20140612

Keywords for this news article include: Lear Corporation.

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Source: Politics & Government Week


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