Skip to content
AkerminMeasure. Monitor. Improve. Compare Products
Review

Extech 407750 Review: Sound Level Meter With PC Connectivity

The Extech 407750 is a sound level meter whose defining feature is a serial PC interface for recording noise over time. The Amazon listing for it carries only a title, so this review is written from Extech's documentation and explains what a PC-connected meter offers over a display-only meter like the SL510.

By the Akermin Editorial Team · 4 min read

As an Amazon Associate, Akermin earns from qualifying purchases. Product links on this page are affiliate links.

Extech 407750 Review: Sound Level Meter With PC Connectivity

Generic · 407750, Audio/Video Test Equipment Sound Level Meter, Digital W/ RS232 Interface

View on Amazon

Price and availability are shown on Amazon and can change at any time.

Verdict

The 407750 is a digital sound level meter with a serial interface for a PC, and that interface is the reason to buy it over a display-only meter. A meter that can stream readings to a computer turns a spot check into a record: the noise of a plant room across a shift, a classroom through a day, or a boundary during a night. The Amazon listing is thin, giving only the model number and a description, so this review relies on Extech’s documentation. From that, the 407750 measures in decibels with the A and C weightings and fast and slow response common to Extech’s 407-series, and shows the value on an LCD. Buyers who need a calibrator in the box should look at the 407732-KIT; buyers who only need a display should consider the SL510.

Who It Is For

  • Facilities and HVAC staff who want to log plant or duct noise over time.
  • Consultants and estates teams documenting noise for a report rather than a spot reading.
  • Anyone who already has a serial logging setup from other Extech meters.

Documented Specifications

Item Documentation
Measurement Sound pressure level in dB
Weighting and response A and C weighting; fast and slow response (Extech 407-series documentation)
Interface RS-232 to PC
Display Digital LCD
Amazon listing Title only, generic brand; no feature bullets

A Note on the Listing

The current Amazon listing for this model is unusually sparse: it names the model, describes it as a digital sound level meter with an RS-232 interface and gives no bullets, and the brand field is generic rather than Extech. That is not a reason to distrust the product, but it is a reason to confirm that the item shipped is the Extech 407750 and to download the datasheet from Extech before relying on any figure. Where we give specifications in this review, they come from Extech’s documentation for the 407-series, not from the listing.

What PC Logging Adds

A sound level meter’s display shows the level now. Many noise questions are about time: how loud is it on average over a shift, how often does it exceed a threshold, and what happens at night when nobody is there to watch. Streaming readings over RS-232 into logging software answers those. The practical requirements are a USB-to-serial adapter for a modern computer, software that reads the meter’s output format, and a stable position for the meter and microphone. For occasional spot checks the interface is unused and a simpler meter is better value.

Weighting and Response

A-weighting approximates the ear’s sensitivity and is used for almost all occupational and environmental noise limits. C-weighting is flatter and is used for peak measurements and for low-frequency noise from plant. Fast response follows fluctuating noise; slow response averages it for a steadier number. Which to use is set by the guidance you are measuring against, and our guide to choosing a sound level meter explains the combinations.

Calibration

A sound meter reading is only as good as its last check against a calibrator, a device that produces a known level at the microphone. The 407750 does not come with one in this listing. For any measurement that will be reported, a calibrator check before and after is standard practice, which is why the 407732-KIT bundles one. See how to read a calibration certificate for what a formal calibration adds.

Strengths

  • PC interface for logging noise over time.
  • Standard weightings and responses for general noise work.
  • Extech 407-series build and documentation.

Limitations

  • Amazon listing gives no specifications; verify with Extech.
  • RS-232 requires an adapter and software on a modern PC.
  • No calibrator included.

How It Compares

The Extech 407732-KIT pairs a Type 2 meter with a calibrator, the right choice when readings must be verified. The Extech SL510 is a compact Class 2 meter with a backlit display for spot checks. The Extech EN300 includes a basic sound function among five measurements. Choose the 407750 only if logging to a PC is the reason for the purchase.

How We Research

This review is based on Extech’s published documentation for the 407750 and the 407-series, the Amazon listing, which provides only a title, and owner reports for Extech sound meters. We did not run laboratory tests.

Extech 407732-KIT Sound Level Meter Kit, 35-130dB, with Calibrator

Extech 407732-KIT Sound Level Meter Kit, 35-130dB, with Calibrator

View on Amazon
Extech SL510 Sound Level Meter, 35-130 dB, Class 2

Extech SL510 Sound Level Meter, 35-130 dB, Class 2

View on Amazon
Extech EN300 5-in-1 Environmental Meter - Measures Air Velocity, Light, Humidity, Temperature & Sound Level - Compact Multi-Function Tester with Large LCD & Data Hold for Field and Indoor Monitoring

Extech EN300 5-in-1 Environmental Meter - Measures Air Velocity, Light,

View on Amazon

Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.

Frequently Asked Questions

What does the Amazon listing say about the 407750?

Very little. It is listed under a generic brand with the model number, a description as a digital sound level meter with an RS-232 interface, and no feature bullets. We used Extech documentation for the specifications.

What is the RS-232 interface for?

Sending readings to a PC for logging and graphing. A modern laptop needs a USB-to-serial adapter.

Is it a Type 2 meter?

Extech positions its 407-series sound meters as general-purpose meters in the Type 2 class. Check the datasheet for the standard it is stated to meet before using it for compliance work.

Does it include a calibrator?

Not in this listing. The 407732-KIT is the Extech package that includes a calibrator.

Affiliate disclosure: Akermin earns a commission from qualifying Amazon purchases made through links on this page. Our editorial picks are based on documented specifications and owner feedback, not commissions.