Abnormal Sound Detection Using EQ-Based Frequency Emphasis
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Solution Overview
Problem
Existing abnormal sound detection systems struggle to detect slight abnormal sounds generated by target apparatuses due to their low magnitude, making it difficult to identify the occurrence of such sounds accurately.
Innovation Solution
The abnormal sound detection device emphasizes the intensity of sound pressure signals at frequencies related to abnormal sounds using an EQ unit, transforming and analyzing the signals to determine the presence of abnormal sounds through comparison with pre-defined templates, facilitating detection even when the sounds are faint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If abnormal sound detection is performed by analyzing sound pressure data directly, then the detection system remains simple, but slight abnormal sounds cannot be detected due to their low magnitude
Solution Approach 1:
The patent applies parameter changes by transforming the sound pressure signal from the time domain to the frequency domain using FFT, and then emphasizing specific frequency components related to abnormal sounds. This changes the representation parameters of the signal to make slight abnormal sounds detectable through frequency-based differentiation rather than direct amplitude comparison.
Solution Approach 2:
The patent introduces an EQ unit as an intermediary component that processes the frequency-transformed signal by emphasizing abnormal sound frequencies before detection. This intermediary processing stage enhances the detectability of slight abnormal sounds without requiring direct modification of the core detection mechanism.
2Reliability
If the magnitude of abnormal sound is small, then the target apparatus operates nearly normally, but the abnormal sound becomes difficult to detect from the operation sound
Solution Approach 1:
The patent transforms the detection parameter from time-domain amplitude to frequency-domain intensity, allowing slight abnormal sounds to be distinguished by their characteristic frequency signatures rather than overall amplitude. This parameter transformation enables reliable detection even when abnormal sounds are masked within normal operation sound levels.
Solution Approach 2:
The patent applies local quality by selectively emphasizing specific frequency components associated with abnormal sounds while maintaining other frequency components at their original levels. This localized enhancement in the frequency spectrum allows detection of slight abnormal sounds without being overwhelmed by the overall operation sound.
3Measurement precision
If frequency-based emphasis is applied to abnormal sound frequencies, then detection precision for slight abnormal sounds improves, but processing complexity increases
Solution Approach 1:
The EQ unit serves as an intermediary that performs frequency-based emphasis processing in a modular fashion. This separates the complex frequency analysis and emphasis operations from the core detection logic, making the system more manageable and maintainable while achieving high detection precision through frequency-selective enhancement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively detects slight abnormal sounds by enhancing the intensity of relevant frequencies, improving detection precision and accuracy by comparing emphasized signals with pre-determined templates, enabling timely identification of operational anomalies.
Implementation Method 1
an EQ unit (20), which emphasizes an intensity of a sound pressure signal at a frequency included in abnormal sound of the target apparatus (P) in sound pressure signals at frequencies which are equal to or higher than a first frequency and are lower than a second frequency in a frequency characteristic (Fs1) of the operation sound
Data Source
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AI summary
An abnormal sound detection device is configured to detect abnormal sound in operation sound of a target apparatus that is a target object for inspection. The device includes: a sound acquisition unit (10) that is configured to obtain the operation sound of the target apparatus as a sound pressure time signal that is a time signal indicative of a time variation in intensity of sound pressure signals; a signal transform unit (22) that is configured to transform the sound pressure time signal to a frequency characteristic indicative of intensity of the sound pressure signals at respective frequencies; an abnormal sound emphasis unit (23) that is configured to obtain, based on the frequency characteristic, an abnormal sound emphasized signal obtained by emphasizing intensity of a sound pressure signal at a frequency in association with the abnormal sound of the target apparatus among the sound pressure signals at the respective frequencies in the frequency characteristic; and an abnormal sound determination unit (25) that is configured to determine whether the abnormal sound is included in the operation sound of the target apparatus based on the abnormal sound emphasized signal.