JPH0367131A - Analysis of noise - Google Patents

Abstract

PURPOSE:To easily analyze a noise only by processing data by subtracting the value of a certain frequency band width after measuring the noise before operating an object to be measured from the value of the same frequency band width after measuring the noise at the time of operating the object to be measured. CONSTITUTION:In a noise measuring chamber, the object to be measured 1 is stopped and the noise at such a time is measured through a microphone 2 and inducted to a data processing part 4 through a by-path filter 3. The amplitude in a certain frequency band of the inducted background noise is measured by the processing part 4 and stored in a 1st storage part in a memory 12. Next, the object to be measured 1 is operated, and the amplitude in a certain frequency band of the noise at the time of operating the object 1 is obtained, which is stored in a 2nd storage part in the memory 12. The processing part 4 performs the analysis of the noise by subtracting the data of the 1st storage part from the data of the 2nd storage part every corresponding frequency among the data stored in the respective storage parts.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a noise analysis method for analyzing squealing noise from brakes, etc.

B. J of invention! ! Summary The present invention provides a g-sound analysis method that uses a certain frequency after measuring noise during operation of an object to be measured. Noise analysis is made possible by a simple method by subtracting the value in the same frequency band after the noise measurement before operation of the object to be measured from the f-range median value.

C0 Conventional technology As a means to measure noise and analyze its type (frequency, etc.), conventional methods first include setting up an anechoic back chamber, and then determining the noise frequency during measurement within this anechoic chamber. The sound measured with a microphone is passed through a 1/3 octave filter and a frequency band filter (low-pass filter, bypass filter, band-pass filter) and measured with a sound level meter.
The measured data is processed and analyzed.

D0 RM to be solved by the present invention In the case of a method using a combination of the above ■ to ■.

Although the measurement accuracy is improved, the cost of methods ① and ③ is particularly high, making it difficult to perform noise analysis easily.

80 Means and Method for Solving the Problems The present invention is a device for measuring noise values, in which the noise frequency of background noise measured while the object to be measured and the amplitude value of its band are stored as a first memory. Store it in the section. Next, the object to be measured is operated, and the noise frequency and the amplitude value of the band measured during operation are stored in the second storage section. Noise analysis is performed by subtracting the data in the first storage section from the data in the second storage section for each corresponding frequency among the data stored in each storage section.

F. Embodiment The figure shows an example of a measurement system for carrying out the present invention, in which 1 is an object to be measured and 2 is a microphone to detect the noise of the object to be measured 1. 3 is a bypass filter, 4 is a data processing section, and this data processing section 4 is connected to interface 1.
1. Memory 12 having first and second storage sections, cp
u (central processing unit) 13, printer interface 1
4. A CRT interface 15 and a digital input/output section 16 are connected to a bus.

Next, its effect will be explained.

In the noise measurement room, the object to be measured 1 is stopped, the noise at that time is determined at 1g using the microphone 2, and is introduced into the data processing section 4 through the bypass filter 3.In the data processing section 4, the introduced background noise is The amplitude of a certain frequency band is measured and stored in the first storage section in the memory 12.

Σ Ai 5in (it + θ1)−−・−−
--・(1)0 Next, operate the object to be measured 1, and measure the noise during operation (2)
The amplitude in a certain frequency band is determined as shown in the formula and stored in the second storage section within the memory 12.

Σ Bi 5in(it +θ'i) ・−・
−・−・(2)0 The noise during operation is! l! If there are multiple rotation patterns, each pattern is measured.

The data processing unit 4 performs Fourier forward transform and inverse transform to measure the base noise level. Measure.

nl Σ C45in (it ten θ”j) Maifil Here, the bandpass relationship is n1≦j≦n2 and nl is n1
The cut value below the next (for example 200H2) frequency, nl is the cut value above the n2nd (for example 20000 HZ) frequency.

Effects of the G8 Invention As described above, the present invention grasps background noise through frequency analysis, and processes this data and data obtained by frequency analysis of overall noise in the same manner for each frequency band. From the conventional filter processing function,
This is easily possible because it eliminates the need for an anechoic backroom and allows noise analysis to be performed using only data processing.

[Brief explanation of drawings]

The figure is a block diagram showing an embodiment of the present invention. Reference numeral 61 indicates an object to be measured, 2 a microphone, 3 a bypass filter, and 4 a data processing section. Patent applicant Tokihisa Meiden Shainoan Co., Ltd.

Claims (1)

[Claims] In an apparatus for measuring a noise value of a measured object, the first storage section stores the noise frequency and its band amplitude value after the noise measurement while the measured object is stopped; a second storage section that stores the noise frequency and its band amplitude value after the noise measurement; Noise analysis method characterized by subtraction for each band