Active acoustic attenuation and spectral shaping system

• US 5,396,561 A
• Filed: 07/27/1992
• Issued: 03/07/1995
• Est. Priority Date: 11/14/1990
• Status: Expired due to Term

• Current Assignee: Cummins Filtration Incorporated (Cummins Incorporated)
• Original Assignee: Nelson Industries Incorporated (Cummins Incorporated)
• Inventors: Allie, Mark C., Popovich, Steven R.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): LEE, PING
• Application Number:
  US07/920,259
• Time in Patent Office: 953 Days
• Field of Search: 381/71, 381/94, 381/56
• US Class Current: 381/71.11
• CPC Class Codes: G10K 11/17817 between the output signals and the error signals, i.e. secondary path
• CPC Class Codes: G10K 11/17819 between the output signals and the reference signals, e.g. to prevent howling
• CPC Class Codes: G10K 11/1785 Methods, e.g. algorithms; Devices G10K11/1781, G10K11/1783 take precedence
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/112 Ducts vehicle exhausts G10K2210/12822
• CPC Class Codes: G10K 2210/3012 Algorithms
• CPC Class Codes: G10K 2210/3017 Copy, i.e. whereby an estimated transfer function in one functional block is copied to another block
• CPC Class Codes: G10K 2210/3044 Phase shift, e.g. complex envelope processing
• CPC Class Codes: G10K 2210/3045 Multiple acoustic inputs, single acoustic output
• CPC Class Codes: G10K 2210/3049 Random noise used, e.g. in model identification
• CPC Class Codes: G10K 2210/51 Improving tonal quality, e.g. mimicking sports cars

Abstract

An active acoustic system provides attenuation and spectral shaping of an acoustic wave. A phase lock loop (304) phase locks to the input acoustic wave (6) and generates (306) a desired signal or tone (308) in given phase relation therewith. An error signal (44) from an error transducer or microphone (16) is summed (302) with the desired signal (308) and the resultant sum is supplied to the error input (202) of an adaptive filter model (40) which outputs a correction signal (46) to an output transducer or speaker (14) to introduce the canceling and shaping acoustic wave. In other embodiments, various combinations sum the desired signal (308) with the error signal (44), the model output correction signal (46), and the model input signal (42). Speaker and error path compensation (146, 318, 320) and feedback compensation (340) is provided.

Claims

1. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a phase lock loop phase locked to said input acoustic wave and generating a desired signal in given phase relation with said input acoustic wave, a summer summing the error signal from said error transducer and the desired signal from said phase lock loop and supplying the resultant sum to said error input of said model such that said model outputs said correction signal to said output transducer to introduce the canceling and shaping acoustic wave, wherein said model outputs said correction signal to said output transducer such that said desired signal is present in said output acoustic wave and in the error signal from said error transducer to said summer such that the desired signal from said error transducer is canceled at said summer by the desired signal from said phase lock loop and such that said desired signal is absent from said error input to said model, and wherein said desired signal is present in said correction signal.

2. The system according to claim 1 wherein said phase lock loop has an input from said error signal, and phase locks to said input acoustic wave by phase locking to said output acoustic wave by phase locking to said error signal to generate said desired signal in given phase relation with said input signal.

9. The system according to claim 1 wherein said model outputs said correction signal to said output transducer such that said desired signal is present in said output acoustic wave and in the error signal from said error transducer to said summer such that the desired signal from said error transducer is canceled at said summer by the desired signal from said phase lock loop and such that said desired signal is absent from said error input to said model.

10. The system according to claim 9 wherein said desired signal is absent from said correction signal.

3. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a phase lock loop phase locked to said input acoustic wave and generating a desired signal in given phase relation With said input acoustic wave, a first summer summing the error signal from said error transducer and the desired signal from said phase lock loop and supplying the resultant sum to said error input of said model such that said model outputs said correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a second summer summing said desired signal from said phase lock loop with said correction signal from said model and outputting the resultant sum to said output transducer such that said desired signal is present in said output acoustic wave and in the error signal from said error transducer to said first summer and such that said desired signal from said error transducer is canceled at said first summer by said desired signal from said phase lock loop and such that said desired signal is absent from said error input to said model from said first summer.

4. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a phase lock loop phase locked to said input acoustic wave and generating a desired signal in given phase relation with said input acoustic wave, a summer summing the error signal from said error transducer and the desired signal from said phase lock loop and supplying the resultant sum to said error input of said model such that said model outputs said correction signal to said output transducer to introduce the canceling and shaping acoustic wave, an auxiliary noise source introducing auxiliary noise such that said error transducer also senses the auxiliary noise from said auxiliary noise source, a second adaptive filter model having a model input from said auxiliary noise source and modeling said output transducer and the error path between said output transducer and said error transducer, and a copy of said second adaptive filter model having an input from said phase lock loop and having an output to said summer, such that the desired signal is supplied through said copy to the summer.

5. The system according to claim 4 comprising a second copy of said second adaptive filter model having an input from said correction signal and having an output, a second summer having a first input from the error signal from said error transducer and a second input from the output of said second copy of said second adaptive filter model, said second summer having an output to said phase lock loop.

6. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a phase lock loop phase locked to said input acoustic wave and generating a desired signal in given phase relation with said input acoustic wave, a first summer summing the error signal from said error transducer and the desired signal from said phase lock loop add supplying the resultant sum to said error input of said model such that said model outputs said correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a second summer summing said desired signal from said phase lock loop with said correction signal from said model and outputting the resultant sum to said output transducer such that said desired signal is present in said output acoustic wave and in the error signal from said error transducer to said first summer and such that said desired signal from said error transducer is canceled at said first summer by said desired signal from said phase lock loop and such that said desired signal is absent from said error input to said model from said first mentioned summer, an auxiliary noise source introducing auxiliary noise such that said error transducer also senses the auxiliary noise from said auxiliary noise source, a second adaptive filter model having a model input from said auxiliary noise source and modeling said output transducer and the error path between said output transducer and said error transducer, and a copy of said second adaptive filter model having an input from said phase lock loop and having an output to said first summer, such that the desired signal is supplied through said copy to the first summer, a second copy of said second adaptive filter model having an input from said correction signal and having an output, a third summer having a first input from the error signal from said error transducer and a second input from the output of said second copy of said second adaptive filter model, said third summer having an output to said phase lock loop.

7. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a phase lock loop phase locked to said input acoustic wave and generating a desired signal in given phase relation with said input acoustic wave, a summer summing the error signal from said error transducer and the desired signal from said phase lock loop and supplying the resultant sum to said error input of said model such that said model outputs said correction signal to said output transducer to introduce the canceling and shaping acoustic wave, an auxiliary noise source introducing auxiliary noise such that said error transducer also senses the auxiliary noise from said auxiliary noise source, a second adaptive filter model having a model input from said auxiliary noise source and modeling said output transducer and the error path between said output transducer and said error transducer, a first copy of said second adaptive filter model having an input from said phase lock loop and having an output adding with the error signal at the summer, such that the desired signal is supplied through said first copy to the summer, a second copy of said second adaptive filter model having an input from said correction signal and having an output, a second summer summing said correction signal and the desired signal from said phase lock loop and supplying the resultant sum to said output transducer, a third summer summing the error signal from said error transducer and the output of said second copy of said second adaptive filter model and supplying the resultant sum to said phase lock loop for generating said desired signal.

8. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a phase lock loop phase locked to said input acoustic wave and generating a desired signal in given phase relation with said input acoustic wave, a summer summing the error signal from said error transducer and the desired signal from said phase lock loop and supplying the resultant sum to said error input of said model such that Said model outputs said correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a signal generator having an input from said phase lock loop and an output providing said desired signal.

11. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal, a first summer summing the error signal from said error transducer and a desired signal and supplying the resultant sum to said error input of said model, a second summer summing said correction signal from said model and said desired signal and outputting the resultant sum to said output transducer.

12. The system according to claim 11 comprising a second model modeling said output transducer and the error path between said output transducer and said error transducer, and a first copy of said second model having an input from said desired signal and an output to said first summer such that said desired signal is supplied through said firs copy to said first summer.

13. The system according to claim 12 comprising a second copy of said second model having an input from said correction signal and having an output, a third summer summing the error signal from said error transducer and said output of said second copy of said second model and supplying the resultant sum to said first copy of said second model as the desired signal.

14. The system according to claim 13 wherein said resultant sum from said third summer is supplied through a signal generator to said first copy of said second model.

15. The system according to claim 11 comprising a second model modeling said output transducer and the error path between said output transducer and said error transducer, and an inverse copy of said second model having an input from said desired signal and an output to said second summer.

16. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, a first adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a second model modeling said output transducer and the error path between said output transducer and said error transducer, a copy of said second model having an input from said correction signal and having an output, a first summer summing the error signal from said error transducer and said output of said copy of said second model, a second summer summing the error signal from said error transducer and the output of said first summer and supplying the resultant sum to said error input of said first model.

17. The system according to claim 16 wherein said output of said first summer is supplied through a signal generator to said second summer.

18. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, a first adaptive filter model modeling said acoustic system and having a model input receiving an input signal, an error input, and a model output outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a first summer, a second summer summing said correction signal from said first model and a desired signal and outputting the resultant sum to said output transducer, an auxiliary noise source introducing auxiliary noise such that said error transducer also senses the auxiliary noise from said auxiliary noise source, a second adaptive filter model having a model input from said auxiliary noise source and modeling said output transducer and the error path between said output transducer and said error transducer, a copy of said second adaptive filter model having an input from said desired signal, said first summer summing the output of said copy of said second model and the error signal from said error transducer and supplying the resultant sum to said error input of said first model, a third adaptive filter model having a model input from said auxiliary noise source and a model output summed at a third summer with said input signal, the result of the third summer is supplied to the model input.

19. The system according to claim 18 comprising a copy of said third adaptive filter model having an input from the output of said second summer and having an output, and a fourth summer summing said output of said copy of said third adaptive filter model and said output of said third summer and supplying the resultant sum to said model input of said first adaptive filter model.

20. The system according to claim 19 comprising a fifth summer having a first input from said output of said second summer and having a second input from said auxiliary noise source and supplying the resultant sum to said output transducer.

21. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model modeling said acoustic system and having a model input receiving an input signal, an error input, and a model output outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a first summer summing the error signal from said error transducer and a desired signal and supplying the resultant sum to said error input of said model, a second summer summing said desired signal and said input signal and supplying the resultant sum to said model input.

22. The system according to claim 21 comprising an auxiliary noise source introducing auxiliary noise such that said error transducer also senses the auxiliary noise from said auxiliary noise source, a second adaptive filter model having a model input from said auxiliary noise source and a model output summed at a third summer with said input signal, a copy of said second adaptive filter model having an input from said correction signal and having an output summed with said input signal at a fourth summer having an output resultant sum supplied to said second summer for summing with said desired signal.

23. An active acoustic attenuation and spectral shaping system for attenuating and spectrally shaping an input acoustic wave comprising an output transducer introducing a canceling and shaping acoustic wave to attenuate and shape said input acoustic wave and yield an attenuated and spectrally shaped output acoustic wave, an error transducer sensing said output acoustic wave and providing an error signal, a first adaptive filter model modeling said acoustic system and having an error input and outputting a correction signal to said output transducer to introduce the canceling and shaping acoustic wave, a signal generator generating a desired signal, a first summer summing the error signal from said error transducer and said desired signal and supplying the resultant sum to said error input of said model, a second model modeling said output transducer and the error path between said output transducer and said error transducer, a copy of said second model having an input from said correction signal and having an output, a second summer summing the error signal from said error transducer and said output of said copy and outputting the resultant sum to said signal generator.

24. An active acoustic system for modifying an input acoustic wave to yield an output acoustic wave, comprising an error transducer sensing said output acoustic wave and providing an error signal, a first adaptive filter model having an error input responsive to said error signal and providing a correction signal, an output transducer responsive to said correction signal and introducing a modifying acoustic wave to combine with said input acoustic wave to generate said output acoustic wave, a second adaptive filter model modeling at least one of said output transducer and the error path between said output transducer and said error transducer, a signal generator responsive to said second adaptive filter model and to said error signal and generating a desired signal and combining said desired signal with said error signal provided to said error input of said first adaptive filter model.

25. An active acoustic system for modifying an input acoustic wave to yield an output acoustic wave, comprising an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model having a model input responsive to an input signal and an error input responsive to said error signal and providing a correction signal, an output transducer responsive to said correction signal and introducing a modifying acoustic wave to combine with said input acoustic wave to generate said output acoustic wave, a signal generator generating a desired signal and combining said desired signal with said error signal at a first combiner and combining said desired signal with said correction signal at a second combiner, the result from the first combiner is supplied to the error input and the result from the second combiner is supplied to the output transducer, such that said desired signal is present in said output acoustic wave but absent from said error input to said adaptive filter model due to said combining of said desired signal and said error signal.

26. An active acoustic system for modifying an input acoustic wave to yield an output acoustic wave, comprising an error transducer sensing said output acoustic wave and providing an error signal, an adaptive filter model having a model input responsive to an input signal and an error input responsive to said error signal and providing a correction signal, an output transducer responsive to said correction signal and introducing a modifying acoustic wave to combine with said input acoustic wave to generate said output acoustic wave, a signal generator generating a desired signal and combining said desired signal with said error signal at a first combiner and combining said desired signal with said input signal at a second combiner, the result from the first combiner is supplied to the error input and the result from the second combiner is supplied to the model input, such that said desired signal is present in said output acoustic wave but absent from said error input to said adaptive filter model due to said combining of said desired signal and said error signal.