Extech 407736 Sound Level Meter.

Type 2 Sound Level Meter with Calibration Check
Sound Level Meter measures in 2 ranges from 35 to 130 dB with ±1.5 dB accuracy that meets ANSI and IEC Type 2 standards.

Additional Features
This Extech sound meter incorporates a built-in 94 dB calibration check, fast/slow response time, A/C Weighting, Max Hold, and analog AC/DC output for connection to an analyzer or recorder.

What is a Sound Level Meter?
Sound level meters are instruments designed to respond to noise much like the human ear. The measurements taken by sound level meters are compared to known standards to determine if the noise level could have a detrimental effect on human hearing.

Types of Sound Level Meters

• Type 3 — Low cost models for basic sound checks.
• Type 2 — Models that meet OSHA and other ordinance testing requirements.
• Type 1 — Precision for lab testing (Extech doesn't have one).
• Dosimeters — Measure work noise exposure according to OSHA.
• Analyzer — analyzes noise in narrow bands