How to Measure Decibels

To measure decibels at home, fix the microphone position, select and record the weighting and response, check calibration and range, then measure the same operating condition for the same duration. Start with the NIOSH iOS app for occasional screening; our dedicated display pick is the REED R8050, while the R8080 adds timestamped logging. Write down the metric beside the number: a current reading, maximum and whole-session average answer different questions.

Quick picks: choose the record you need

Compare specifications and all conditions

NIOSH iOS app

Our pick for

Occasional screening and saved reports

Documented functions

A/C/Z weighting; LAeq, maximum and C-weighted peak

Important limit

Its Type 2 claim requires a calibrated external microphone

REED R8050

Our pick for

Reading a dedicated display yourself

Documented functions

30–130 dB; A/C; Fast/Slow; data hold and MAX

Important limit

No time-series logging or integrating LAeq documented

REED R8080

Our pick for

Keeping a timestamped history

Documented functions

30–130 dB; A/C; 64,000 stored datapoints; USB downloads

Important limit

Leq is described in PC software; standalone integrating LAeq is not established

Full comparison table ↔

Swipe to compare. Row labels stay visible.

Choice	Our pick for	Documented functions	Important limit
NIOSH iOS app	Occasional screening and saved reports	A/C/Z weighting; LAeq, maximum and C-weighted peak	Its Type 2 claim requires a calibrated external microphone
REED R8050	Reading a dedicated display yourself	30–130 dB; A/C; Fast/Slow; data hold and MAX	No time-series logging or integrating LAeq documented
REED R8080	Keeping a timestamped history	30–130 dB; A/C; 64,000 stored datapoints; USB downloads	Leq is described in PC software; standalone integrating LAeq is not established

Choice	Our pick for	Documented functions	Important limit
NIOSH iOS app	Occasional screening and saved reports	A/C/Z weighting; LAeq, maximum and C-weighted peak	Its Type 2 claim requires a calibrated external microphone
REED R8050	Reading a dedicated display yourself	30–130 dB; A/C; Fast/Slow; data hold and MAX	No time-series logging or integrating LAeq documented
REED R8080	Keeping a timestamped history	30–130 dB; A/C; 64,000 stored datapoints; USB downloads	Leq is described in PC software; standalone integrating LAeq is not established

Sources: NIOSH specifications, R8050 manual, R8080 specifications and software guide. Recommendations reflect those functions.

Set up a comparison you can repeat

Write the question first: “Does changing the fan speed change the level at this chair?” Choose the condition to change deliberately; keep everything else as consistent as possible. Record the appliance setting, door/window positions, other running equipment and any interruptions. This is a practical home comparison plan, not a standardized appliance sound-power test.

REED's manuals specify keeping the meter away from your body, pointing its microphone toward the source and using a tripod for longer monitoring. They warn that blowing air can introduce errors; use the windscreen and avoid putting the microphone in an appliance's air stream. Mark the stand location, measure its height and distance from a named point on the source, and photograph the setup. Positioning instructions

Use this sequence for each session:

1. 1

   Define the comparison

   Name the source setting, location and metric before starting.

2. 2

   Fix the microphone

   Mark position, height and orientation; keep the setup clear of your body and blowing air.

3. 3

   Check the instrument

   Follow its calibration procedure and choose a range without overload or under-range warnings.

4. 4

   Record and repeat

   Keep duration and settings matched; preserve results and note interruptions.

Choose weighting, response and metric

Weighting: REED recommends A for general noise. Report it as dBA; label C-weighted results dBC. OSHA explains that A attenuates very low frequencies much more than C, so do not compare an A reading with a C reading as if only the source changed. Weighting explanation

Response: Fast has a 125 ms time constant; Slow has a 1 second time constant. Slow produces a short, time-weighted average that makes a fluctuating display easier to read, but does not establish an average over your whole session. OSHA response explanation The R8050 manual's wording “average sound level” for Slow describes that response setting; it documents no integrating LAeq function. REED settings

Metric: choose a current level for a spot check, MAX for the highest time-weighted reading, or LAeq for an equivalent continuous A-weighted level over the run. NIOSH lists LAeq, maximum and C-weighted peak separately; MAX is not a true peak measurement. Preserve the actual label and duration rather than relabelling every result “average dB.” NIOSH metric definitions

Check calibration and range before recording

NIOSH recommends calibration before and after measurements. Use the instrument's documented procedure and an appropriate reference; a quiet room or a video played through a speaker is not a known calibration reference. Record the calibrator/reference, its setting, the before/after indications and any adjustment. If you have no reference, write “not checked” instead of “calibrated.” Calibration guidance

The R8080 manual says UNDER means the selected range starts too high and OVER means its upper limit was exceeded. Change range and repeat the affected run. Both REED meters' published coverage starts at 30 dB: a result below that floor is outside their stated coverage, not a measurement of silence or an exact quieter level. Range instructions

Choose the duration before starting. For a cycling source, include the operating phase you intend to compare and document it. Keep talking, handling and unrelated interruptions out of the run, or mark them and repeat. Save the result before resetting; NIOSH provides Start, Pause, Reset and saved measurement reports in its help guide.

Copy this blank session record

Use a separate sheet for each condition. Leave unavailable metrics blank; do not manufacture them from a display reading.

This worksheet combines REED's setup controls with NIOSH's report fields and calibration guidance; the extra context is our recommendation for making a comparison reviewable.

Worked example: compare matching records

Invented teaching example, not thisMETER readings or a prediction of fan performance. Our chosen plan is a steady fan at low versus high speed, unchanged room and stand, 60 seconds per run. The R8050 microphone is 1 m from the fan's front grille and 1 m above the floor, pointed toward it but outside the air stream. These distances and duration are example choices, not prescribed survey settings.

The illustrative maxima differ by 10 dB. That comparison describes these matching MAX records; it does not supply LAeq, isolate the fan from background sound, or establish an accurately calibrated absolute level. Repeat the conditions, complete the calibration checks and investigate inconsistent repeats before relying on a small change. REED specifies ±1.4 dB accuracy, which is a manufacturer claim, not a complete uncertainty budget for this setup. R8050 specifications

• Yes: Compare the same metric with matching weighting, response, placement and duration.
• No: Do not substitute an under-range indication for a valid quieter reading.
• No: Do not compare dBA with dBC or MAX with LAeq as equivalent results.
• Partly: Stored samples describe a history; the averaging method still needs checking.

Decibels are logarithmic. OSHA specifically warns against calculating an average by adding the displayed levels and dividing by the sample count. Likewise, do not subtract a source-off dB reading from a source-on reading and call the difference the source's isolated level. Decibel arithmetic

Decibel level chart: examples, not household limits

NIDCD publishes these familiar-sound examples as average decibel ratings:

Source: NIDCD sound examples. The ranges overlap; a label such as “movie theater” does not specify your microphone location or measurement duration. Use the chart to understand the scale, not to replace a reading at your chosen position.

Best screening starting point: NIOSH iOS app

The NIOSH app offers saved/shared reports and LAeq. Its published ±2 dBA accuracy comes from laboratory evaluation. The Type 2, IEC 61672 Part 3 claim requires a calibrated external microphone; the help guide describes evaluation of the complete phone/microphone system and continuing work on Parts 1 and 2.

The built-in-microphone setup and a calibrated external-microphone setup are different configurations. Record which you used. NIOSH currently cannot verify Android-app accuracy across that hardware range; do not transfer its results to a different app.

Best dedicated display: REED R8050

Choose the R8050 for manual spot checks and MAX records. REED specifies A/C weighting, Fast/Slow response and IEC 61672-1 Class 2; its documented functions do not include time-series logging or integrating LAeq.

Range conflict: the specification table gives high range 60–130 dB, while the operating instructions say 65–130 dB. Both give low range 30–100 dB. Confirm the transition with REED if it matters to your plan.

Package variant: the standard meter lists a windscreen, battery and case. REED's datasheet identifies R8050-KIT as the meter with an R8090 calibrator and R8888 hard case. That accessory bundle does not add logging. The manual describes requesting a calibration certificate separately, while the datasheet also lists R8050-NIST and R8050-KIT-NIST variants with NIST certification; check the documentation supplied with the exact package.

Best for stored history: REED R8080

The R8080 stores timestamped readings at intervals from 1 to 60 seconds. Set its clock and interval before recording. The interval is separate from Fast/Slow response: a stored point does not document everything between points.

REED describes CAL Leq in PC software; its software guide describes LEQ over a specified period and Excel export. The instrument manual does not establish onboard integrating LAeq. Preserve the original file and identify the software, interval and selected period behind any calculated result; request method details if a formal brief requires them.

The download support page lists Windows 11, while the software guide stops at Windows 10. Confirm installation compatibility before buying for exports; no macOS/Linux package is listed there.

Buying guide: when to change tools

Keep the display meter for a manual record; choose logging when you need timestamps and a history to inspect. For speaker/room tuning, REW's documentation describes a microphone/software setup that measures frequency and impulse responses. That is a different job from reporting an overall dB level. Use our home-theater SPL tools guide for that setup, or the sound level meter buying guide for broader tool selection.

How we choose

This is research from current official REED product pages, linked manuals and software documents, NIOSH guidance, NIDCD examples and REW documentation, checked November 2, 2026. Instrument specifications remain manufacturer claims; no physical product testing underlies these recommendations. The worksheet and hypothetical comparison are editorial teaching tools. See How we measure for our reporting policy.

Verdict

Start with a repeatable record: fixed placement, documented settings, matched duration and an accurately named metric. Use NIOSH on iOS for screening, the R8050 for dedicated display checks, or the R8080 for timestamped history. Keep microphone configuration, range warnings and calibration status attached to every comparison.