# Extech SL400 Personal Noise Dosimeter # Extech SL400 Personal Noise Dosimeter ## Key Features At A Glance - Measures frequency-weighted noise exposure with A, C, and Z weighting plus C and Z peak sound level - Datalogs up to 999,999 readings in sound level meter mode with sampling times from 1 second to 24 hours - Adjustable Criterion Level (30 to 140 dB), Threshold Level (30 to 140 dB), and Exchange Rate (3, 4, 5, or 6 dB) - Sound level mode displays SPL, min/max, time-averaged Leq, peak, and sound exposure level (SEL) - Compliant with IEC 61252-1993, IEC 67672-1-2003, ANSI S1.25-1992, ANSI S1.4-1983, and ANSI S1.43-1997 - Measurement range of 30 to 90 dB and 50 to 110 dB with C/Z peak coverage up to 143 dB; ±1.4 dB accuracy at 94 dB / 1 kHz - USB interface with Windows 7 and 8 compatible software for setup, stored event retrieval, and real-time analysis - Compact 4.2 x 2.6 x 1.3 inch form factor at 7 oz with belt clip, clip-on microphone with 32 inch cable, windscreen, and carrying case The Extech SL400 is a compact, lightweight personal noise dosimeter with a USB interface designed to test noise exposure and provide noise surveys for compliance with OSHA, MSHA, DOD, ACGIH, and ISO standards. It includes PC software to control setup and retrieve stored events or analyze real-time measurements, supporting the workflow of safety professionals who need to document worker sound exposure across an 8-hour shift. Listed applications include personal accumulated noise exposure measurement, workplace noise assessment, and OSHA and other regulatory agency compliance work. For employees exposed to loud noise, sound level monitoring is essential to determine what protective measures are required, and the SL400 supports both OSHA and IEC noise accumulation surveys to determine total sound exposure over an 8-hour period. ## Brand Heritage Extech Instruments is owned by FLIR Systems, which itself became part of Teledyne Technologies in 2021. The Extech brand continues to operate as a recognized name in handheld environmental and safety test instruments, with the FLIR Systems copyright still appearing on current product documentation. ## Compare Other Models in This Series The SL400 is positioned in the Extech catalog as a personal noise dosimeter — a body-worn instrument designed to accumulate a worker's total sound exposure across a shift rather than to take a single spot reading of a noise source. The clip-on 0.5 inch microphone on a 32 inch cable is the architectural signature of this category: the microphone sits at the worker's shoulder near the hearing zone while the instrument body clips to a belt. Within Extech's sound measurement line, dosimeters and sound level meters serve different jobs. A dosimeter like the SL400 answers the question of how much cumulative noise a specific worker received over a shift, while a handheld sound level meter answers the question of how loud a specific location or machine is at a specific moment. Both categories share underlying acoustic measurement technology but differ in form factor, datalogging behavior, and the regulatory frameworks they are typically used to satisfy. Each new SL400 listed in our catalog is its own dedicated product page with condition-matched pricing and availability. If you are comparing options across condition tiers, the individual product pages carry the specifics relevant to your purchasing process. The SL400 is specifically called out as available with optional Limited NIST traceability for A and C weighting, ordered with the -NISTL suffix to receive the product plus a calibration certificate. This is the relevant ordering detail for buyers whose internal procedures or external audits require documented traceability on the weightings used for occupational noise measurement. Comparison across condition tiers and ordering variants for the SL400 centers on two factors documented on the datasheet: whether the unit is ordered with the standard SL400 part number or with the -NISTL suffix for Limited NIST traceable calibration on A and C weighting, and whether the optional 94 dB calibrator is included to support the before and after calibration checks referenced in the specifications. Specifications themselves — measurement range, frequency weighting, response rates, memory depth, measurement modes, and the standards compliance list — are common to the SL400 platform as printed on this datasheet. The comparison table that follows highlights the configuration and documentation differences relevant to your selection. Model Measurement Range Frequency Weighting Bandwidth **SL400** 30 to 90 dB, 50 to 110 dB A, C, Z 20 Hz to 8 kHz SL400-NISTL 30 to 90 dB, 50 to 110 dB A, C, Z 20 Hz to 8 kHz Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below. ## Accessories Supplied - Belt clip - Clip-on 0.5" (12.7mm) microphone with 32" (81.3cm) cable - Windscreen - 9V battery - Software - USB cable - Carrying case ## Product Core & Specifications Specification Value Standards IEC61252-1993, IEC67672-1-2003, ANSI S1.25-1992, ANSI S1.4-1983, ANSI S1.43-1997 Ranges (Accuracy) 30 to 90 dB, 50 to 110 dB; C, Z Peak: 70 to 140 dB / C and Z Peak: 90 to 143 dB (Accuracy: ±1.4 dB @ 94 dB 1 kHz) Frequency Weighting A, C, Z Response Rate Fast, Slow, Impulse Bandwidth 20 Hz to 8 kHz Memory Dose: 10,000 points / SLM: 999,999 points Criterion Level 30 to 140 dB in 0.1 dB steps Threshold Level 30 to 140 dB in 0.1 dB steps Exchange Rate 3, 4, 5 or 6 dB Measurement Duration 5, 10, 15, or 30 minutes; 1, 2, 4, 8, 10, 12, or 24 hours Measurement Modes (Dose) %Dose, Lxmax, Lxyp, Lxmin, Lxeq, SEL (LAE), PeakMAX, LAVG, TWA, LEP, LN% Measurement Modes (SLM) SPL, Lxmax, Lxyp, Lxmin, Lxeq, SEL (LAE), PeakMAX Dimensions 4.2 x 2.6 x 1.3 in. (107 x 65 x 33 mm) - excludes connector on top Weight 7 oz. (198 g) including batteries and microphone cable Interface USB (Windows® 7 and 8 compatible software) Power 9V battery UPC Code 793950474006 **Important:** Optional 94 dB calibrator available to perform before and after calibration checks per ANSI standards.**Important:** An optional 94 dB calibrator is required to perform 'before' and 'after' calibration checks per ANSI standards; the calibrator is not included with the base unit and must be ordered separately.Recommended pairing: pair the SL400 with the optional 94 dB acoustic calibrator referenced in the datasheet to perform before and after calibration checks per ANSI standards on each survey. **Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.** ## Details - **Price:** 849.0 USD - **Vendor:** Extech - **Type:** Data Log - **Tags:** Extech, Manufacturers, Meters & DAQ, product_manual_group_2, Product_new, Sound ## Variants | Variant | Price | Available | |---------|-------|-----------| | Default Title | 849.00 USD | In stock | ## Images - SL400 Extech Sound Meter --- > Source: [ValueTronics](https://valuetronics.com/products/sl400-extech-sound-meter-new) > Updated: 2026-05-30