Time weighting (fast/slow response time). Sound level measurements using any grade of SLM can be fast (125 milliseconds time constant) and slow (one second time constant). These weightings date back to the time when SLMs had analogue meters and defined the speed at which the meters moved. As these time constants were set in standards, these have continued in digital meters, now being calculated or simulated before being displayed, stored or used to calculate other acoustic parameters that need time weighting.
Following terms are used to express sound level, clearly indicating time weighting as well as frequency weighting: LAS (slow, A weighted sound level), LAF (fast, A weighted sound level), LCS (slow, C weighted sound level) and LCF (fast, C weighted sound level).
Slow response is most often used for listening to conservations/OSHA programmes and is an averaging of sound level over time.
Fast response is most commonly used for product noise-reduction efforts and can detect quick noise bursts such as fireworks.
Sound level data logger. Tango and EXTECH HD600 data-logging SLMs measure, display and store sound-level measurement data. Up to 20,000 readings can be stored in the meter, each with date and time stamp. Readings can be recalled on the meter’s display or can be downloaded to a PC.
Included software permits users to view, graph, print and export data to a spreadsheet. This capability can be applied to many applications such as airport-noise analysis, construction-zone monitoring, traffic intersections, concert venues, environmental impact studies and others.
Noise dosimeter. These are ideal for industries where shifts are involved, such as construction (building sites), entertainment (orchestras) and emergency services (police forces). Rather than having a health and safety officer follow or stay with workers throughout assessment, each employee can be left to his or her own device, while the noise dosimeter takes accurate and detailed measurements throughout the day. This type of device is particularly useful for measuring daily noise exposure of workers who move about a lot during their shifts and for those who work at night.
“Our SLM is built on internal standard 94dB/1kHz square-wave generator for calibrating certain internal amplifier circuits. An electric condenser microphone is used for high accuracy and long-term stability,” says Vijay Nagori, CEO of Instruments & Machinery Sales Corp.
Optimus, the latest generation of SLMs, combines the latest digital technology with ease of use, guarantees high performance with class 1 and class 2 SLMs, measures everything you need simultaneously to save time, is designed for basic, occupational and environmental noise measurements, meets standards from around the world (including the UK, EU, OSHA, MSHA and ACGIH), type approved from PTB, LNE & Applus+ to IEC 61672-1:2002, is easy to upgrade at any time and carries a 15-year warranty.