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O-Solution 変動音解析機能 OS-0526

Although the volume of sound is not particularly loud, there are many "bothersome sounds" in the world. For example, sounds emitted by interior parts of a car that can be heard occasionally while driving, such as "clattering" and "buzzing," or the unusual sound of a small motor's rotation, like a "humming" noise. There are several reasons for what makes a sound "bothersome," but sounds with significant temporal variation often feel unpleasant even if their volume (level) is not very high. Fluctuation sound analysis is a method that can extract only the large components of temporal variation that are not influenced by level. This allows for the quantification of various temporal variation characteristics that were difficult to detect with traditional FFT, basic roughness, and fluctuation intensity. Additionally, it enables a deeper analysis of various sound designs (seasoning) by evaluating sound timbre (pitch) and temporal variation cycles along two axes, surpassing the capabilities of conventional techniques.

  • Transmission gear grinding noise (clattering)

    Transmission gear grinding noise (clattering)

  • Abnormal buzzing sound from a small motor.

    Abnormal buzzing sound from a small motor.

  • Engine intake and exhaust sound (rumbling)

    Engine intake and exhaust sound (rumbling)

  • Refrigerator compressor operating sound (beep)

    Refrigerator compressor operating sound (beep)

  • O-Solution Variable Sound Analysis Function OS-0526

How to view examples of fluctuating sound analysis: a sound that fluctuates slowly at a high pitch.

Please be careful with the volume. Sound will be played.

  • How to view examples of fluctuating sound analysis: a sound that fluctuates slowly at a high pitch.

Case Study of Fluctuating Sound Analysis ② Low Sounds with Rapid Fluctuations

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  • Case Study of Fluctuating Sound Analysis ② Low Sounds with Rapid Fluctuations

Variable Sound Simulator Function

Before the simulation

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after the simulation

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The fluctuation sound simulator allows users to adjust and evaluate sound by removing unwanted fluctuation components or emphasizing those that are easier to hear, while checking the results of fluctuation sound analysis. Unlike traditional methods that use band-reject filters for removing fluctuation components, which can also attenuate other components in that frequency range, the fluctuation sound simulator can remove, emphasize, or extract fluctuation sounds while keeping the frequency characteristics almost intact.

  • Variable Sound Simulator Function

Here, we will compare the frequency characteristics when removing fluctuating components using a fluctuating sound simulator and the conventional method of a band-reject filter. In both cases, the rattling sound was no longer audible. However, when using the fluctuating sound simulator, the frequency characteristics showed little change from the original signal, whereas in the case of the band-reject filter, the frequency characteristics changed significantly because it attenuated and removed the components in the relevant frequency band.

  • Frequency characteristics when removal is performed using a variable sound simulator.
    Frequency characteristics when removal is performed using a variable sound simulator.
  • Frequency characteristics when removal is performed using a band reject filter.
    Frequency characteristics when removal is performed using a band reject filter.

Case Study of Fluctuating Sound Analysis: Abnormal Noise of a Small Motor

Abnormal buzzing sound from a small motor.
Abnormal buzzing sound from a small motor.

A person was listening to the operating sound of a small motor to make a pass/fail judgment. Frequency analysis was conducted to enable numerical judgment, but it was not successful. By executing fluctuation sound analysis, which focused on variable sounds, the differences between good and defective products were clarified.

Model name Product Name quantity
OS-5100 platform 1
OS-0522 FFT Analysis Function 1
OS-0526 Fluctuation Sound Analysis Function 1

*Equipment for recording sound (high-performance sound level meter, FFT analyzer, etc.) is required. Please consult with us.



Good quality, clear sound (no abnormal noise).

Defective product 1: Abnormal sound present (somewhat muffled sound mixed in)

Defective product 2: Abnormal sound present (a muffled sound is mixed in)

  • Case Study of Fluctuating Sound Analysis: Abnormal Noise of a Small Motor

Fluctuating Sound Analysis Case Study: T/M Gear Tooth Noise (Ratting Noise)

Please be careful with the volume. Sound will be played.

img-o-solution-os0526-01
Transmission gear grinding noise (clattering)

The tonal quality of gear tooth noise contains components in the 800 Hz range, but in FFT analysis, the sound is buried in the background noise level, making it impossible to identify features. In 'fluctuation sound analysis', the values in the grid increase in the 800 Hz range (vertical axis) and the 20 Hz range (horizontal axis). This allows for representation of features even for sounds from which such characteristics cannot be extracted based solely on sound volume.

Model name Product Name quantity
OS-5100 platform 1
OS-0522 FFT Analysis Function 1
OS-0526 Fluctuation Sound Analysis Function 1

*Equipment for recording sound (high-performance sound level meter, FFT analyzer, etc.) is required. Please contact us for more information.

  • Fluctuating Sound Analysis Case Study: T/M Gear Tooth Noise (Ratting Noise)