Sound Level Meter - Noise Meter
Sound level meter instruments and analyzers by Brüel & Kjær are designed for class 1 measurement accuracy, ease-of-use and unprecedented flexibility. In fact, our latest generation of sound level meters can be directly managed via smartphones, and with the addition of our feature-expanding apps, you can tailor your sound level meter to any measurement task. It's been over 60 years since Brüel & Kjær invented the world's first portable sound level meter. And we still lead the industry today.
B&K 2245 SOUND LEVEL METER
With NOISE PARTNER
B&K 2245 sound level meter is an easy-to-use solution for dedicated noise measurement tasks. The instrument comes with a range of apps, each tailored to provide functionality for your specific job-to-do.
B&K Type 2250 and Type 2270
Sound Level Meter / Analyzer
Providing an award‐winning design based on extensive research among technicians, engineers and consultants, B&K Type 2250 and Type 2270, are both equipped to handle the most demanding measurement tasks.
THINGS TO CONSIDER BEFORE CHOOSING YOUR MEASURING
WHAT IS A SOUND LEVEL METER
A sound level meter (SLM) is an instrument (commonly hand-held) that is designed to measure sound levels in a standardized way. It responds to sound in approximately the same way as the human
ear and gives objective, reproducible measurements of sound pressure levels.
WHAT IS A SOUND LEVEL METER USED FOR?
Sound level meters are used to measure and manage noise from a variety of sources, including industrial plants, road and rail traffic and construction work.
With the addition of typical urban situations, such as sports events, outdoor concerts, leisure parks and residential and commercial neighbours, you have many different sources of sound, each with different characteristics that pose specific problems for the professionals who assess them.
HOW DOES A SOUND LEVEL METER WORK?
The microphone converts the sound signal to an equivalent electrical signal. The most suitable type of microphone for sound level meters is the condenser microphone, which combines precision with stability and reliability.
The electrical signal produced by the microphone is at a very low level, so it is made stronger by a preamplifier before it is processed by the main processor. Signal processing includes applying frequency and time weightings to the signal as specified by international standards such as IEC 61672 – 1, to which sound level meters conform.
The display shows the sound level in decibels, typically with a descriptor showing the selected combination of time and frequency-weighting (eg; LAeq or LCpeak). The signal may also be available at output sockets, in either AC or DC form, for connection to external instruments such as a data acquisition system, to provide a record and/or for further processing.
HOW TO USE A SOUND LEVEL METER
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.
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.
IEC 61672-1 (international standard) defines frequency weightings A, C and Z, but other frequency weightings are occasionally used in specialized applications.
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.
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.
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.
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
ISO 1996: ASSESSMENT OF ENVIRONMENTAL NOISE
The standard is in two parts:
- Part 1 (2016): Basic quantities and assessment procedures
- Part 2 (2017): Determination of sound pressure levels