Patent Publication Number: US-8542844-B2

Title: Sound modification system and method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a sound modification system for modifying engine and road noises in vehicles. More specifically, the invention relates to a sound modification system for reducing noise; enhancing engine, exhaust and other desirable performance sounds; or a combination thereof. 
     2. Brief Description of the Prior Art 
     Automobile manufacturers continuously strive to reduce sound or noise levels in the passenger compartment of vehicles. Active noise reduction (ANR) systems have been developed to enable the audio system in the vehicle to introduce sound waves into the passenger compartment of a vehicle to cancel other sound waves, and thus, quiet the passenger compartment. 
     Some systems have been made that are capable of producing sounds that emulate performance sounds; however, these systems generally are not configured for a particular engine or are expensive to include in vehicles. In addition, as vehicle manufacturers have reduced noise, vibration and harshness (NVH) through various techniques, many enthusiasts miss hearing performance sounds which have also been reduced. More specifically, the more efficient engines and advanced technology now found in vehicles, many performance sounds are more difficult for a driver in the passenger compartment of the vehicle to hear. As such, there is a desire for a vehicle that has reduced NVH while still providing thrilling audio feedback to enthusiasts. Even further, electric cars have engines that are nearly silent to the human ear, and therefore, do not provide any audible engine noise. One negative of reduced engine noise is that many undesirable NVH sounds are now audible. Engine sound enhancement (ESE) systems have been developed to amplify such engine noises or other noises in electric vehicles for the safety of pedestrians. There is a significant and continuing need for improved ANR and ESE systems for vehicles to provide the driver of a vehicle with a more pleasurable acoustical atmosphere in the passenger compartment of the vehicle under a range of driving conditions. 
     SUMMARY OF THE INVENTION 
     The invention relates to a sound modification system for modifying engine and road noises in vehicles. More specifically, the invention relates to a sound modification system for reducing noise; enhancing engine, exhaust and other desirable performance sounds; or a combination thereof. 
     The invention provides for a sound modification system for a vehicle having a passenger compartment and a method for managing sound in a vehicle. The system includes a vehicle speed sensor for generating a vehicle speed signal, a vehicle acceleration sensor for generating a vehicle acceleration signal, a throttle position sensor for generating a throttle position signal and/or a cruise control sensor for generating a cruise control signal. The system also includes an active noise reduction (ANR) controller for generating an opposing sound wave signal substantially one hundred and eighty degrees (180°) out of phase with respect to a sound wave to be reduced, e.g. engine noise. The system further includes an engine sound enhancement (ESE) controller for selectively generating an engine enhancement sound wave signal substantially in phase with respect to a noise to be amplified, e.g. engine noise. The ANR and ESE controllers may be stand alone modules, one combined module or integrated into an amplifier or radio head unit. A loudspeaker is in communication with the ANR and ESE controllers for receiving the opposing sound wave signal and the engine enhancement sound signal and for outputting sound waves. The loudspeaker may be incorporated into the vehicle&#39;s entertainment system. The system also includes a sound modification controller in communication with the at least one sensor for receiving the vehicle speed signal, the vehicle acceleration signal, the throttle position signal and/or the cruise control signal and in communication with the ANR and ESE controllers. The sound modification controller automatically activates the ANR controller and deactivates the ESE controller in response to the vehicle being in a steady state driving condition, e.g. when the vehicle is travelling at a near-constant speed. The sound modification controller automatically activates the ESE controller and deactivates the ANR controller in response to the vehicle being in a non-steady state driving condition, e.g. accelerating. Alternatively, both the ANR and ESE controllers could be activated at the same time, depending on the driver&#39;s preference or selected driving mode, e.g. sport, luxury, performance, etc. 
     The method of controlling the sound in a vehicle having a passenger compartment includes the steps of sensing a driving condition of the vehicle as being either a steady state driving condition with the vehicle travelling at a near-constant speed or a non-steady state driving condition and outputting a first sound wave in response to the driving condition of the vehicle changing from the non-steady state driving condition to the steady state driving condition. 
     The invention is advantageous because, in the steady state driving condition, such as using cruise control or maintaining a constant speed on a highway, the occupants of the vehicle generally want the passenger compartment to minimize NVH and other noises. Therefore, the sound modification controller activates the ANR controller and deactivates the ESE controller, which results in a quieter passenger compartment. In contrast, at times, the driver wants to hear performance related sounds, such as the engine and other exhaust notes from the vehicle. During the non-steady state driving condition, the sound modification controller activates the ESE controller and deactivates the ANR controller. This amplifies desired performance sounds for the driver, and the sound modification controller controls the ANR and ESE controllers to achieve an optimal passenger compartment experience for the driver during any driving condition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given here below, the appended claims, and the accompanying drawings in which: 
         FIG. 1  is a schematic drawing of the sound modification system in a vehicle; 
         FIG. 2  is a schematic drawing of an exemplary ANR controller; 
         FIG. 3  is a schematic drawing of an exemplary ESE controller; and 
         FIG. 4  is a flow chart of the exemplary method of managing the sound in a vehicle having a passenger compartment. 
     
    
    
     DETAILED DESCRIPTION OF THE ENABLING EMBODIMENTS 
     Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a sound modification system  20  for controlling audible noise in the passenger compartment of a vehicle  22  having an engine  24  is generally shown in  FIG. 1 . The system may be used in any type of vehicle  22 , but is particularly applicable to automobiles, such as trucks, cars, sport utility vehicles, crossover vehicles and vans. The engine  24  of the vehicle  22  could be an internal combustion engine, an electric motor or any other type of engine. 
     The system of the exemplary embodiment includes an active noise reduction (ANR) controller  26  for reducing sound waves to quiet the passenger compartment of the vehicle  22 ; an engine sound enhancement (ESE) controller  28  for amplifying sounds; and a sound modification controller  30  for controlling the ANR and ESE controllers  26 ,  28 . It should be appreciated that the ANR, ESE and sound modification controllers  26 ,  28 ,  30  could be separate units, or they could be contained within one unitary unit, e.g. a computer, amplifier module, radio head unit, etc. 
     The vehicle  22  of the exemplary embodiment includes a vehicle mode selector  32  for allowing the driver of the vehicle  22  to choose between a first mode, a second mode and a third mode. In the exemplary embodiment, the first mode is a sport mode, the second mode is a luxury mode and the third mode is an automatic mode. Of course, the types of selections may vary based on the type of vehicle or the desired operating modes. The vehicle mode selector  32  could be any type of input for allowing the driver to choose between the operating modes. For example, the vehicle mode selector  32  could be a switch or a knob in the passenger compartment of the vehicle  22 . It should be appreciated that the vehicle mode selector  32  could have any number of different settings other than those of the exemplary embodiment and could be tied into the traction control system of the vehicle  22 . For example, when a driver deactivates the traction control system of the vehicle  22 , it could be akin to selecting the sport mode. The vehicle mode selector  32  generates a vehicle mode signal corresponding to the vehicle mode selected by the driver, the use of which will be described in further detail below. 
     The sound modification controller  30  is in communication with the vehicle mode selector  32  for receiving the vehicle mode signal. When the vehicle  22  is in the luxury mode, the sound modification controller  30  of the exemplary embodiment continuously operates the ANR controller  26  and deactivates the ESE controller  28 . In other words, when the driver chooses the luxury mode, the ANR controller  26  reduces sound waves, and thus quiets, the passenger compartment of the vehicle  22 . 
     When the vehicle  22  is in the sport mode, the sound modification controller  30  of the exemplary embodiment continuously operates the ESE controller  28  and deactivates the ANR controller  26 . In other words, when the driver chooses the sport mode, the ESE controller  28  operates to continuously amplify engine sounds, or other sounds, in the passenger compartment. 
     The sound modification controller  30  of the exemplary embodiment is also configured to switch between operating the ANR and ESE controllers  26 ,  28  when the vehicle  22  is in the automatic mode. In the exemplary embodiment, the sound modification controller  30  alternates between the ANR and ESE controllers  26 ,  28  depending on the driving condition of the vehicle  22 . Specifically, when the vehicle  22  is in a steady state driving condition, the sound modification controller  30  only activates the ANR controller  26  to quiet the passenger compartment of the vehicle  22 . In contrast, when the vehicle  22  is in a non-steady state driving condition, then the sound modification controller  30  only activates the ESE controller  28  to amplify sounds in the passenger compartment of the vehicle  22 . The steady state driving condition in this specification refers to a situation, such as cruise control, when the vehicle  22  is in a “steady state” of motion. For example, the steady state driving condition may be defined as when the vehicle speed remains at 55 mph, or when the vehicle  22  is travelling within a predetermined range of speed, e.g. ±5 mph. Alternatively, the steady state driving condition may be defined as when the magnitude of the vehicle acceleration remains less than one meter per second squared (1 m/s 2 ). 
     The sound modification controller  30  is configured to switch between the ANR and ESE controllers  26 ,  28  at a rate that is slow enough to not be noticeable to a human. In other words, the switching between the ANR and ESE controllers  26 ,  28  happens smoothly, and the driver or any other passengers in the passenger compartment of the vehicle  22  should not be able to tell when the sound modification controller  30  switches between the ANR and ESE controllers  26 ,  28 . In the exemplary embodiment, the sound modification controller  30  fades in and out the ANR and ESE controllers  26 ,  28  at a rate of less than 3 decibels per second. 
     To determine whether the vehicle  22  is in the steady state driving condition, the sound modification controller  30  is in communication with a plurality of sensors  34 ,  36 ,  38 ,  40 ,  42 , including for example, an engine speed sensor  34 , a vehicle speed sensor  36 , a vehicle acceleration sensor  38 , a throttle position sensor  40  and a cruise control sensor  42 . The vehicle speed sensor  36  senses the speed of the vehicle  22  and generates a vehicle speed signal. The vehicle acceleration sensor  38  senses the acceleration of the vehicle  22  and generates a vehicle acceleration signal. The throttle position sensor  40  senses the position of a throttle pedal  48  in the vehicle  22  and generates a throttle position signal. The cruise control sensor  42  senses whether the cruise control system in the vehicle  22  is operating or deactivated and generates a cruise control signal. The sound modification controller  30  of the exemplary embodiment can use these sensors  34 ,  36 ,  38 ,  40 ,  42  and their respective outputs to calculate the driving condition of the vehicle  22  according to a predetermined algorithm, as will be discussed in further detail below. The sound modification controller  30  of the exemplary embodiment is also in communication with an engine control unit  44  (ECU) through a controller area network  46  (CAN) bus to provide an additional input to the algorithm. It should be appreciated that the sound modification controller  30  could be in communication with a number of different sensors in addition to or in place of those shown in the exemplary embodiment for determining if the vehicle  22  is in the steady state driving condition. 
     The engine speed sensor  34  is operatively coupled to the engine  24  of the vehicle  22  and generates an engine speed signal. Typically, the engine speed sensor  34  measures the speed of the engine in revolutions per minute (RPM). A variety of other sensors could also be coupled to the engine  24  for monitoring other conditions. For example, the various sensors could measure the torque being produced by the engine  24 , the power being produced by the engine  24 , the temperature of the engine  24 , etc. These sensors could also be in communication with the sound modification controller  30  and used in the algorithm to determine the driving condition of the vehicle  22 . 
     The sound modification controller  30  uses an algorithm that automatically determines that the vehicle  22  is in a steady state driving condition whenever the cruise control system is activated. Thus, when the vehicle  22  is in the automatic mode and the cruise control system is activated to keep the vehicle  22  at a near-constant speed, the ANR controller  26  remains activated and the ESE controller  28  remains deactivated. 
     The algorithm of the sound modification controller  30  can also determine if the vehicle  22  is in a steady state driving condition when the cruise control system is not activated. In the exemplary embodiment, the sound modification controller  30  determines that the vehicle  22  is in a steady state driving condition when the vehicle  22  remains within a five mile per hour range (±5 mph) for greater than five minutes. Alternatively, the algorithm could use the outputs of other sensors  34 ,  36 ,  38 ,  40 ,  42  to determine the driving condition of the vehicle. For example, if the throttle pedal  48  remains at a position for a predetermined period of time, the sound modification controller  30  would determine that the vehicle  22  is in the steady state driving condition. Similarly, if the engine  34  remains within a predetermined non-idle speed range for a predetermined time, then the sound modification controller  30  would determine that the vehicle  22  is in the steady state driving condition. 
     The ANR controller  26  of the exemplary embodiment is in communication with the engine speed sensor  34  of the engine for receiving the engine speed signal and to at least one microphone  50  disposed either in the passenger compartment, the engine compartment or exterior of the vehicle  22 . As shown in  FIG. 2 , the ANR controller  26  of the exemplary embodiment includes an ANR memory  52  for storing a noise profile of the engine and an ANR processor  54  for generating an opposing sound wave signal. The ANR processor  54  generates the opposing sound wave signal as a function of the engine speed signal and the sound received by the microphone  50 . The opposing sound wave signal is substantially one hundred and eighty degrees (180°) out of phase with the sound waves being reduced. The noise profile of the engine is preferably a pre-set profile of the sounds produced by the engine  24  at various engine speeds. Thus, with the engine profile, the ANR controller  26  can generate an opposing sound wave signal to reduce the noise produced by the engine  24  solely as a function of engine speed. Preferably, when the sound modification controller  30  phases in the ANR controller  26 , the ANR controller  26  progressively increases the amplitude of the opposing sound wave signal until the opposing sound wave signal has an amplitude substantially equal to the amplitude of the sound waves produced by the engine  24  at a rate that is not noticeable to a human, e.g. less than 3 decibels per second. Alternatively, the ANR controller  26  could be configured to only reduce, and not entirely cancel sound waves by increasing the amplitude of the opposing sound to a level that is less than the amplitude of the sound wave being quieted. This is useful, for example, to allow the occupants of the passenger compartment to hear a subtle rumble of the engine  24 . Likewise, when the ANR controller  26  is phased out, or deactivated, the ANR controller  26  progressively decreases the amplitude of the opposing sound wave signal. 
     In addition to the engine speed sensor  34  and the microphone  50 , the ANR controller  26  may also use other inputs to generate the opposing sound wave signal. For example, the ANR controller  26  could use the engine ECU  44 , the vehicle speed sensor  36 , the vehicle acceleration sensor  38  or the throttle position sensor  40  as additional inputs for generating the opposing sound wave signal. With these inputs, the opposing sound wave signal could reduce more noises than just the engine noise. For example, the ANR controller  26  could be configured to also reduce transmission noises, differential noises, road noises, wind noises or any other noises coming from outside of the passenger compartment of the vehicle  22 . 
     The ANR controller  26  could be configured to reduce noises over a predetermined frequency range, a plurality of frequency ranges or for the complete audible noise spectrum. The ANR controller  26  could also be configured to only reduce noises above a predetermined noise level. The determination of what noise level to review may depend on a variety of vehicle status signals. For example, when the vehicle  22  is traveling above a set speed and the windows are open, the ANR controller  26  may only look for a narrow range of noise levels as all other noise levels the ANR controller  26  would typically look for may be irrelevant due to the noise from the windows. These parameters of when to look for particular noise levels and when not to look for particular noise levels may be set by the vehicle manufacturer. 
     The ESE controller  28  is in communication with the engine speed sensor  34  of the engine for receiving the engine speed signal and to a microphone  50  disposed either in the passenger compartment, the engine compartment or exterior of the vehicle  22 . As shown in  FIG. 3 , the ESE controller  28  of the exemplary embodiment includes an ESE memory  56  for storing a noise profile of the engine and an ESE processor  58  for generating an engine enhancement sound wave signal. The engine enhancement sound wave signal is substantially in phase with the noise being produced by the engine  24 , or any other noise to be amplified. The noise profile of the engine  24  is a pre-set profile of the sounds produced by the engine at various engine speeds. Thus, with the engine profile, the ESE controller  28  can generate an engine enhancement sound wave signal for amplifying engine noise solely as a function of engine speed. The engine enhancement sound wave signal can have any amplitude depending on the desired level of amplification. Preferably, when the sound modification controller  30  phases in the ESE controller  28 , the ESE controller  28  progressively increases the amplitude of the engine enhancement wave signal until the opposing sound wave signal to the desired level of amplification at a rate that is not noticeable to a human, e.g. less than 3 decibels per second. Likewise, when the ESE controller  28  is phased out, or deactivated, the ESE controller  28  progressively decreases the amplitude of the opposing sound wave signal at a rate that is not noticeable to a human. 
     In addition to the engine speed sensor  34  and the microphone  50 , the ESE controller  28  may also use other inputs to generate the engine enhancement sound wave signal. For example, the ESE controller  28  could use the engine ECU  44 , the vehicle speed sensor  36 , the vehicle acceleration sensor  38  or the throttle position sensor  40  as additional inputs for generating the engine enhancement sound wave signal. With these inputs, the engine ESE controller  28  could amplify more noises than just the engine noise. For example, the ESE controller  28  could be configured to amplify tire squeal noises, the whine of a turbo/supercharger or any other noises. 
     The ANR and ESE controllers  26 ,  28  are in communication with at least one loudspeaker  60  in the passenger compartment. The loudspeaker  60  in the passenger compartment receives the opposing sound wave signal and the engine enhancement sound wave signal and outputs sound waves into the passenger compartment. The loudspeaker  60  could be disposed anywhere within the passenger compartment of the vehicle  22 , including on the headrests of the seats in the vehicle  22 . The ESE controller  28  may also be in communication with at least one loudspeaker  60  on the exterior of the vehicle  22  for projecting sound waves outside of the vehicle  22 . It should be appreciated that the loudspeaker  60  in the interior of the vehicle  22  could be a part of the vehicle&#39;s entertainment system and does not have to be separately dedicated to noise cancellation and/or enhancement. 
     The invention further provides a method of controlling the sound in the passenger compartment of a vehicle  22 . The method of the exemplary embodiment starts with the step  100  of providing an ANR controller  26  and an ESE controller  28 . The method continues with the step  102  of sensing an engine speed of the engine  24 . As explained above, in the exemplary embodiment, the engine speed of the vehicle  22  is determined with an engine speed sensor  34 . 
     The method then continues with the step  104  of sensing a vehicle  22  operating mode. In the exemplary embodiment, the operating modes are a sport mode, a luxury mode and an automatic mode. If the vehicle  22  is in the luxury mode, then the method proceeds with the step  106  of generating with the ANR controller  26  a continuous opposing sound wave having an amplitude substantially equal to the amplitude of a sound wave to be reduced and substantially one hundred and eighty degrees (180°) out of phase with the sound waves to be reduced. As described above, alternately, the ANR controller  26  could quiet, rather than cancel, noise. If the ANR controller  26  is reducing noise, then the opposing sound wave will have an amplitude smaller than the amplitude of the sound wave to be quieted. If the sound wave to be reduced is noise from the engine of the vehicle  22 , then the ANR controller  26  could generate the opposing sound wave as a function of the sensed engine speed. It should be appreciated that the sound wave to be reduced could be from other sources than the engine  24 , e.g. road noise or wind noise. 
     If the vehicle  22  is in the sport mode, then the method proceeds with the step  108  of sensing a sound wave to be amplified and generating with the ESE controller  28  a continuous engine enhancement sound wave substantially in phase with a sound wave to be amplified. If the sound wave to be amplified is noise coming from the engine  24  of the vehicle  22 , then the ESE controller  28  could generate the engine enhancement sound wave as a function of the sensed engine speed. However, it should be appreciated that the sound wave to be amplified could come from sources other than the engine  24 , e.g. the tires. 
     If the vehicle  22  is in the automatic mode, then the method continues with the step  110  of sensing a cruise control state of the vehicle  22  as one of activated or deactivated. In other words, the method determines whether the driver is using a cruise control system in the vehicle  22  to maintain a near-constant speed. If the cruise control system of the vehicle  22  is activated, then the method continues with the step  112  of determining that the vehicle  22  is in a steady state driving condition. 
     If the vehicle  22  is in the automatic mode and the cruise control system is deactivated, then the method continues with the step  114  of sensing a vehicle speed of the vehicle  22 . The method then continues with the step  112  of determining that the vehicle  22  is in a steady state driving condition in response to the vehicle  22  speed remaining within a predetermined range for a predetermined period of time. In other words, the vehicle  22  is in a steady state driving condition if it remains at a near-constant speed. For example, the steady state driving condition could be when the vehicle  22  stays within a five mile per hour range (±5 mph) for greater than five minutes. 
     If the vehicle  22  is in the automatic mode and the steady state driving condition, then the method continues with the step  116  of sensing a sound wave to be reduced and generating with the ANR controller  26  an opposing sound wave having an amplitude substantially equal or less than the sound wave to be reduced and substantially one hundred and eighty degrees (180°) out of phase with respect to the sound wave to be reduced. 
     If the vehicle  22  is in the automatic mode and is not in the steady state driving condition, then the method continues with the step  118  of determining that the vehicle is in a non-steady state driving condition. The method then continues with the step  120  of sending a sound wave to be amplified and generating with the ESE controller  28  an engine enhancement sound wave substantially in phase with a sound wave to be amplified. 
     Steps  110  and  114  are performed continuously or periodically while the vehicle  22  is in the automatic mode. Therefore, any change in the driving condition of the vehicle  22  will be detected. If the vehicle  22  leaves the steady state driving condition, then the method continues with the step  122  of progressively decreasing the amplitude of the opposing sound wave and generating with the engine sound controller and progressively increasing the amplitude of an engine enhancement sound wave substantially in phase with a sound wave to be amplified. In other words, the engine enhancement sound wave is phased in simultaneously to the opposing sound wave being phased out when the vehicle  22  transitions from the steady state driving condition to the non-steady state driving condition. Also in the exemplary embodiment, the phasing out of the opposing sound wave and the phasing in of the engine enhancement sound wave take place at a rate that is not noticeable to a human. Specifically, in the exemplary embodiment, the opposing and engine enhancement sound waves are phased in/out at a rate of less than 3 decibels per second. 
     If the vehicle  22  transitions from the non-steady state driving condition to the steady state driving condition, then the method continues with the step  124  of progressively decreasing the amplitude of the engine enhancement sound wave and generating with the ANR controller  26  and progressively increasing the amplitude of the opposing sound wave. In the exemplary embodiment, the phasing out of the engine enhancement sound wave and the phasing in of the opposing sound wave take place at a rate that is not noticeable to a human, e.g. less than 3 decibels per second. 
     The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and do come within the scope of the invention. Accordingly, the scope of legal protection afforded this invention can only be determined by studying the following claims.