소음측정기 - 사운드 레벨 메터

브뤼엘앤드케아의 소음 측정 & 분석기는 클래스1의 정확도를 보유하고 있으며, 쉽고 간편하게 이용할 수 있도록 설계되었습니다. 4차 산업을 준비하는 소음 측정기는 스마트폰을 통해 직접 관리할 수 있고, 원하는 응용 프로그램을 추가하여 어떠한 상황에서도 소음을 측정할 수 있게 고객 맞춤형으로 디자인되고 있습니다. 브뤼엘앤드케아가 세계 최초의 휴대용 소음 측정기를 발명한지 60년이 넘었습니다. 여전히 브뤼엘앤드케아는 소음 측정 분야를 이끌고 있는 글로벌 기업입니다

B&K 2245 소음 측정기 - 노이즈 파트너

B&K 2245 소음 측정기는 완벽한 소음을 측정하기 위해 설계된 사용하기 편리한 솔루션입니다. 이 장비에는 특정한 작업을 위해 고안된 기능을 제공하도록 다양한 앱을 탑재하고 있습ㄴ다.

자세히 보기

B&K 2250과 2270 소음 측정기 및 분석기

B&K 2250과 2270는 엔지니어, 컨설턴트, 관련 소음 측정 담당자를 광범위하게 연구한 후 개발되었으며, 해외 디자인 기관에서 디자인 대상을 수상하였습니다. 이러한 제품 설계를 바탕으로 가장 까다로운 측정도 완벽하게 처리할 수 있습니다.

2250 단일 채널 소음 측정기이지만, 2270 소음과 진동을 동시에 측정하는 채널입니다

소음 측정기란 

소음 측정기는 사람의 귀와 거의 같은 방식으로 소리에 반응할 수 있게 설계된 기기입니다. 소음 측정기의 목적은 음압 레벨의 객관적이고, 재현가능한 측정을 제공하는 것입니다.

소음 측정기 혹은 사운드(노이즈) 레벨 메터는 동일한 의미로 사용됩니다. 소음 측정기에 대해 이야기할 때 가장 큰 차이점은 국제 표준에 정의된 정확도입니다. 브뤼엘앤드케아의 모든 소음 측정기는 세계 최고의 국제 표준을 준수하고 있습니다.

소리 용어에 대한 정보는 Sound and Vibration Glossary에서 확인해주시기 바랍니다.

소음 측정기 사용법

소음측정기는 다음과 같은 사업 분야에서 사용됩니다:

브뤼엘앤드케아는 오랫동안 소음과 진동 측정에 대한 대부분의 주제를 다루는 풍부한 정보를 보유하고 있습니다. 이와 관련된 모든 자료는 지식 공유를 위해 사용자분들에게 무료로 공개하고 있습니다.

웹사이트의 지식 센터를 방문하시고 로그인하신 후 자료를 다운받으시기 바랍니다.

Time weighting specifies how the SLM reacts to changes in sound pressure. It is an exponential averaging of the fluctuating signal, providing an easy-to-read value.

The analyzer applies Fast, Slow and Impulse (or ‘F’, ‘S’ and ‘I’) time weightings, which are the required weightings according to most international and national standards and guidelines. Environmental assessment standards usually specify which time weighting to use.


Time Weighting
The signal is processed through the weighting filters, and the resulting sound pressure level is displayed in decibels (dB) referenced to 20 μPa on the analyzer’s screen. The sound pressure level values are updated at least once per second.

Assessing a fluctuating noise level means getting a value for a level that is, in simple terms, the average level. The ‘equivalent continuous sound level’, Leq, is known around the world as the essential averaged parameter.

Leq is the level that, had it been a steady level during the measurement period, would represent the amount of energy present in the measured, fluctuating sound pressure level. It is a measure of the averaged energy in a varying sound level. It is not a direct measure of annoyance, though extensive research has shown that Leq correlates well with annoyance.

Leq can be measured directly with most professional sound level meters, and is sometimes called an integrating sound level meter. If an A-weighting filter is used, it is expressed as LAeq, the measurement of the equivalent continuous sound level using the A-weighted filter network
Frequency weighting adjusts how the sound level meter responds to different sound frequencies. This is necessary because the human ear’s sensitivity to sound varies according to the sound’s frequency.

IEC 61672-1 (international standard) defines frequency weightings A, C and Z, but other frequency weightings are occasionally used in specialized applications.
Frequency Rating
 
A-weighting – dBA/dB(A)
A-weighting adjusts a signal in a way that resembles the human ear’s response at medium-range levels. It is based on the 40 dB equal loudness curve. The symbols for the noise parameters often include the letter ‘A’ (for example, LAeq) to indicate that frequency weighting has been included in the measurement.
 
A-weighting is required for nearly all environmental and workplace noise measurements and is specified in international and national standards and guidelines. A-weighting filters cover the full audio range, 10 Hz to 20 kHz.
 
C-weighting – dBC/dB(C)
The response of the human ear varies with the sound level. C frequency weighting corresponds to the 100 dB equal loudness curve, that is to say, the human ear’s response at fairly high sound levels.

C-weighting is mainly used when assessing peak values of high sound pressure levels. It can also be used, for example, for entertainment noise measurements, where the transmission of bass noise can be a problem.
 
Z-weighting – dBZ/dB(Z)
‘Zero’ frequency weighting is a flat frequency response between 10 Hz and 20 kHz ±1.5 dB excluding microphone response.
 
Today, the A-weighting network is the most widely used frequency weighting. C-weighting does not correlate well with subjective tests because the equal loudness contours were based on experiments which used pure tones — and most common sounds are not pure tones, but very complex signals made up of many different tones.
When more detailed information about a complex sound is required, the frequency range from can be divided up into sections or bands. This is done with electronic or digital filters, which reject all sound with frequencies outside the selected band. These bands usually have a bandwidth of either one octave or a third of an octave.

An octave is a frequency band where the highest frequency is twice the lowest frequency. For example, an octave filter with a centre frequency of 1 kHz admits frequencies between 707 and 1414 Hz but rejects all others. (The name octave stems from the fact that an octave covers eight notes of the diatonic musical scale). A third octave covers a range where the highest frequency is 1.26 times the lowest frequency.
Frequency analysis
The process of thus dividing a complex sound is termed frequency analysis and the results are presented on a chart called a spectrogram.

After the signal has been weighted and/or divided into frequency bands, the resultant signal is amplified, and the Root Mean Square (RMS) value determined in an RMS detector. The RMS is a special kind of mathematical average value. It is of importance in sound measurements because the RMS value is directly related to the amount of energy in the sound being measured.
International standards are important either because they are used directly or because they provide inspiration or reference for national standards. There are two main international bodies concerned with standardization.
 
The International Organization for Standardization (ISO) primarily deals with a methodology to ensure that procedures are defined to enable comparison of results. The International Electrotechnical Commission (IEC) ensures that instruments are compatible and can be interchanged without major loss of accuracy or data.

IEC 61672 - INTERNATIONAL STANDARD
“IEC 61672 – Electroacoustics – Sound level meters” is the current international standard that sound level meters should meet to satisfy most modern regulations. It specifies “three kinds of sound measuring instruments” - the “conventional” sound level meter, the integrating-averaging sound level meter, and the integrating sound level meter.

The standard is published in three parts:
  • Part 1: Specifications: Requirements for sound level meter performance and functionality for class 1 and class 2 sound level meters
  • Part 2: Pattern evaluation tests: Details of the tests necessary to verify conformance to all mandatory specifications given in IEC 61672-1. Used by test laboratories to ensure that instruments meet manufacturers claims.
  • Part 3: Periodic tests: Procedures for periodic testing of sound level meters conforming to the class 1 or class 2 requirements of IEC 61672-1:2002
It defines the basic terminology including the central Rating Level parameter and describes best practices for assessing environmental noise.

ISO 1996: ASSESSMENT OF ENVIRONMENTAL NOISE

ISO 1996 is a central standard within environmental noise assessment, acting as a reference work on the subject and commonly referred to by regional standards and regulations.

The standard is in two parts:
  • Part 1 (2016): Basic quantities and assessment procedures
  • Part 2 (2017): Determination of sound pressure levels
Calibration is an adjustment of your sound measuring instrument to measure and display correct values. The sensitivity of the transducer, as well as the response of the electronic circuitry, can vary slightly over time or could be affected by environmental conditions such as temperature and humidity. 

While you are unlikely to ever experience a large drift or change in sensitivity, it is nevertheless, good practice to regularly check the calibration of your measuring instrument before and after each set of measurements. This is best done by placing a portable acoustic calibrator directly over the microphone, providing a precisely defined sound pressure level to which the sound level meter can be adjusted.

In addition to checking calibration before and after measurements, many regulations and standards governing sound level measurements often also require that your sound level meter is calibrated in a laboratory once every 12 or 24 months.