Amprobe SM-20-A Sound Meter

The Amprobe SM-20 type 2 sound meter measures and records sound pressure levels (spl) in environmental quality control and acoustic analysis applications, such as when checking compliance with noise pollution regulations and health and safety codes. The meter can record measurements for future reference, and it comes with a data cable for connecting the meter to a computer to transfer recorded data for viewing and analysis on a computer using the included software. It has two measurement settings. The “A” weighting is for taking measurements where there is low to moderate ambient noise, such as in an office. The “C” weighting is for taking measurements where there is loud low-frequency background noise, such as in machine shops. The meter offers a choice of two response speeds. The fast 125-millisecond response setting measures the average sound level in environments with steady ambient sound, and the slow 1-second response setting measures peak noise levels in environments with fluctuating ambient sound. The 1/2-inch condenser microphone comes with a windscreen to shield the microphone in outdoor conditions with wind speeds over 10 m/sec (22.3 mph). The maximum or minimum reading mode displays the highest or lowest reading in a session to track sudden increases or decreases in measurements. The data hold function keeps a reading on the display even after the meter is disconnected or the measurement changes. The meter's backlit liquid crystal display (LCD) is readable in low light and shows measurements in 0.1 dB increments up to 4 digits. The auto-power off function turns off the unit after 5 minutes of non-use to conserve battery life. The included software can be installed on computers that run the Windows 95, 98, NT, ME, 2000, XP, or 7 operating system.

Specifications

H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.

Sound meters measure sound pressure levels both to check acoustic fidelity and to verify compliance with noise pollution regulations in health and safety codes. The meters are used in a range of environments, including homes, schools, airports, automotive and machine shops, concert halls, recording studios, and hospitals. There are two classes of sound level meters. Type 1 sound meters have a wider frequency response and a tighter tolerance than type 2 sound level meters, and they are commonly used in applications that require precise measurements, such as research and law enforcement. Type 2 sound meters are less precise than type 1 meters and are used for taking general measurements, such as measuring noise levels in a machine shop. Sound level meters are weighted for frequency response according to their intended use. The most commonly used weightings are A, C, and Z. The A weighting imitates the response of the human ear to soft or moderate noise levels and can be used in most environmental noise measurement applications. The C weighting imitates the response of the human ear to loud noises and can be used in noisy environments. The Z weighting measures flat frequency response between 10Hz and 20kHz and is often used for reference measurements.

Amprobe manufactures electrical testing equipment for commercial, industrial, and home use. The company was founded in 1948 and is headquartered in Everett, WA

What’s in the Box?

• SM-20 sound level meter
• (1) 9V battery (installed)
• Windscreen
• Software CD
• RS232 to mini-stereo cable
• Carrying case
• Instructions