Electrical audio signal processing systems and devices – Directive circuits for microphones
Reexamination Certificate
1997-10-14
2001-11-27
Chang, Vivian (Department: 2644)
Electrical audio signal processing systems and devices
Directive circuits for microphones
C381S071100, C367S119000
Reexamination Certificate
active
06324290
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a method for and an apparatus for diagnosing a sound source and a vibration source, and more particularly to a method for and an apparatus for diagnosing a sound source and a vibration source which, in a transmitting system in which one or a plurality of sound sources or vibration sources constitute causes of sounds or vibrations at an evaluation point, make it possible to visually and quantitatively diagnose the sound sources or vibration sources contributing largely to the evaluation point, and can be used in making effective improvements.
2. Description of Related Art
Conventionally, as a method of analyzing the contribution of sound sources or vibration sources to an evaluation point, a method has been proposed in which, in a frequency domain, correlational components are determined from a transfer function between the respective sound sources or vibration sources and the evaluation point, and the rates of contribution of the sound sources or vibration sources to the evaluation point are determined from these correlational components.
Further, in recent years, a technique has been proposed for diagnosing the contribution of sound sources or vibration sources by using adaptive digital filters in a time domain (Japanese Patent Application Laid-Open No. 526722).
However, with the above-described conventional method of analyzing contribution in the frequency domain, only amplitude information is used, and phase information is not considered. Therefore, if there are strong correlations among inputs, analysis becomes difficult. In addition, it takes time in analysis, so that it is impossible to obtain results instantly, and steady data for a long time is required.
On the other hand, with the above-described conventional method of analyzing contribution in the time domain, analysis in operating conditions, i.e., in real time, becomes possible. In consequence, however, only the time waveform is obtained, and since the rates of contribution are evaluated from the magnitude of the amplitude of the time waveform, it is possible to determine only qualitative and approximate rates of contribution although they are determined in real time. Thus, there is a problem in that it is impossible to evaluate the degrees of instantaneous, quantitative contribution (contribution rates).
SUMMARY OF THE INVENTION
The present invention has been devised in view of the above-described circumstances, and its object is to provide a method for and an apparatus for diagnosing a sound source and a vibration source, which have higher practical values by making it possible to evaluate a rate of quantitative contribution in real time.
To attain the above object, in accordance with a first aspect of the present invention, there is provided a method of diagnosing a rate of contribution of a sound source or a vibration source, comprising the steps of: detecting sounds at a sound source or vibrations at a vibration source in the form of an analog value and then converting the analog value into a digital value, or detecting sounds at the sound source or vibrations at the vibration source in the form of a digital value; performing digital filtering by using the digital value and a filter factor which is changed such that a result of digital filtering approaches a targeted value; and computing the rate of contribution of the sound source or the vibration source to an evaluation point on the basis of the result of digital filtering, and displaying the same.
In accordance with a second aspect of the present invention, there is provided an apparatus for diagnosing a rate of contribution of a sound source or a vibration source, comprising: means including a sensor for detecting sounds or vibrations at a predetermined position in the form of an analog value and an analog-digital converting circuit for converting the analog value into a digital value, or including a sensor for detecting sounds or vibrations at a predetermined position in the form of a digital value; a plurality of filters each adapted to perform digital filtering by using a filter factor and one of a plurality of digital values generated by delaying the digital value a plurality of times; changing means for changing at least one of the filter factors such that a difference between a total sum of results of digital filtering and a targeted value becomes minimum; and a contribution-rate computing circuit for computing the rate of contribution to an evaluation point by using outputs of the plurality of filters within a predetermined time when the difference becomes minimum.
In accordance with a third aspect of the present invention, there is provided an apparatus for diagnosing a rate of contribution of a sound source or a vibration source, comprising: means including a plurality of sensors each detecting sounds or vibrations at a predetermined position in the form of an analog value and a plurality of analog-digital converting circuits each converting the analog value into a digital value, or including a plurality of sensors each detecting sounds or vibrations at a predetermined position in the form of a digital value; a plurality of filters each adapted to perform digital filtering by using the digital value and a filter factor; changing means for changing at least one of the filter factors such that a difference between a total sum of outputs of the plurality of filters and a targeted value becomes minimum; and a contribution-rate computing circuit for computing the rate of contribution to an evaluation point by using the outputs of the plurality of filters within a predetermined time when the difference becomes minimum.
In accordance with the first aspect of the present invention, sounds at a sound source or vibrations at a vibration source are detected in the form of an analog value, and the analog value is converted into a digital value, or sounds at a sound source or vibrations at a vibration source are detected directly in the form of a digital value. Digital filtering is performed by using the digital value and a filter factor which is changed such that the result of digital filtering approaches a targeted value. The rate of contribution of the sound source or the vibration source to an evaluation point is diagnosed on the basis of the result of digital filtering. As a result, it is possible to diagnose the contribution of the sound source or the vibration source to the evaluation point when the result of digital filtering, i.e., in the case of a multiplicity of inputs, the total sum of digital filtering of the multiplicity of inputs, and, in the case of a single input, the total sum of digital filtering of a plurality of inputs generated in the past by delaying the single input, converges to the targeted value. In addition, in the present invention, the rate of contribution of the sound source or the vibration source to the evaluation point is computed and displayed. For this reason, the degree of contribution can be evaluated at a glance.
In the second aspect of the present invention, the analog value of sounds or vibration at a predetermined position detected by an analog sensor is converted into a digital value by the analog-digital converting circuit for converting the analog value into a digital value, or sounds or vibration at a predetermined position are detected directly in the form of a digital value by a digital sensor. Each of the filters performs digital filtering by using a filter factor and one of the plurality of digital values generated in the past by delaying the digital value. The changing means changes at least one of the filter factors such that the difference between the filter output and the targeted value becomes minimum, and the contribution-rate computing circuit computes the rate of contribution to the evaluation point by using outputs of the plurality of filters within a predetermined time when the difference becomes minimum. This rate of contribution is displayed on a display unit.
Thus, in the second aspect of the present invention, sinc
Kudoh Hirokazu
Mizuno Keiichiro
Murakami Kazutomo
Bridgestone Corporation
Chang Vivian
Oliff & Berridge PLC.
Pendleton Brian T.
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