NIOSH Sound Level Meter vs Bolo Finder
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
NIOSH Sound Level Meter
This free app measures sound levels and noise exposure using your smartphone. Developed by acoustics experts, it provides professional-grade metrics and guidance on hearing protection and noise prevention.
- Sound level measurement
- Noise dosimetry
- Hearing hazard information
- Hearing protector guidelines
- Data reporting and sharing
- Microphone calibration
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This award-winning app combines the best features of professional sound level meters and noise dosimeters into a simple, easy-to-use package. - Developed by experienced acoustics engineers and hearing loss experts. - Completely FREE – No ads, no limited features, and no in-app purchases. - Tested and validated (accuracy ± 2 dBA) according to standards in a reverberant chamber at NIOSH acoustics lab – the only proper method to validate accuracy. - Trusted source and world-class expertise in noise and hearing research. - Meets Type 2 requirements of IEC 61672:3 SLM standard when used w/ external microphone.* - Provides the most relevant metrics found in professional sound instruments today. Averages such as LAeq and TWA, Max and Peak Levels, Noise Dose and Projected Dose according to NIOSH and OSHA standards, and all three major weighting networks (A, C, and Z). - Capability to calibrate either internal or external microphone. Reporting and Sharing data. - Up-to-date informational screens on what noises are considered hazardous, how to conduct a noise measurement, how to properly select a hearing protector, and guidelines for preventing hearing loss, all at the palm of your hand. - Excellent and timely support from NIOSH hearing experts. - Support for Apple's Health (Hearing) app. * Celestina M, Hrovat J, Kardous CA [2018]. Smartphone-based sound level measurement apps: Evaluation of compliance with international sound level meter standards. Applied Acoustics, 139:119-128. https://doi.org/10.1016/j.apacoust.2018.04.011 More resources (including instructional videos and a user manual), a science blog, FAQ, and information about how to interpret results can be found on the NIOSH SLM website https://www.cdc.gov/niosh/topics/noise/app.html
Bolo Finder
This app automatically monitors popular online marketplaces for specific collectible items. It instantly alerts you when your desired item is listed, saving you the effort of manual searches across multiple platforms. View all your alerts in one consolidated feed.
- Monitors eBay, Etsy, Facebook Marketplace, Craigslist
- Instant listing alerts
- Aggregated view of alerts
- Manual search elimination
- Collectible tracking
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With our unique monitoring algorithms, we will monitor and instantly alert you when your collectible is listed on Ebay, Etsy, Facebook Marketplace, and Craigslist.You no longer need to search all these sites manually, we will continuously search them for you and send you a notification so you can open your Bolo Finder app and see an aggregated view of your alerts and what site we found it on.
Screenshots
Verdict
The clearest difference is review sentiment: NIOSH Sound Level Meter at 64% against Bolo Finder's 0%. NIOSH Sound Level Meter also leads on rating (4.7 vs 3.5) and ratings volume (17K vs 2). Bolo Finder's advantage is update cadence (fortnightly vs every 4 months) and iOS requirement (13.0 vs 15.0). On price, ads, in-app purchases and monetization model there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
NIOSH Sound Level Meter holds the better App Store score, 4.7 against 3.5. That said, the two scores are not equally well evidenced: NIOSH Sound Level Meter has 17K ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 64% of NIOSH Sound Level Meter's written reviews are positive against 0% of Bolo Finder's.
NIOSH Sound Level Meter ships an update every 4 months, Bolo Finder fortnightly. The most recent releases landed on September 24, 2026 and September 19, 2026 respectively.
| Parameter | NIOSH Sound Level Meter | Bolo Finder |
|---|---|---|
| Price | Free | Free |
| Rating | 4.7 (17K ratings) — better | 3.5 (2 ratings) |
| Positive reviews | 64.5% of reviews — better | 0.0% of reviews |
| Number of ratings | 17K — better | 2 |
| Update frequency | Every 4 months | Fortnightly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPod | iPhone, iPod |
| Requires iOS | 15.0 | 13.0 — better |
| Further details — not scored | ||
| Size | 6 MB | 18 MB |
| Age rating | 4+ | 4+ |
| Developer | EA LAB | CSC Beyond LLC |
Customer experience
NIOSH Sound Level Meter
Bolo Finder
Bugs and requests
NIOSH Sound Level Meter
Reported bugs
3 issues- Inconsistent or inaccurate readings in some cases
- Inability to properly connect and use external microphones
- Freezing or crashing when minimizing the app
Requested features
4 requests- Ability to save and export measurement sessions
- Option to run the app in the background while the screen is locked
- Integration with Apple Health for long-term noise exposure tracking
- Frequency-specific noise measurements (e.g., A-weighted, C-weighted)
Bolo Finder
Not enough reviews yet to summarise bugs or requests.
In-app purchases
NIOSH Sound Level Meter
No in-app purchases
Bolo Finder
No in-app purchases
Questions
Is NIOSH Sound Level Meter free?
Is Bolo Finder free?
Which has better reviews, NIOSH Sound Level Meter or Bolo Finder?
Do NIOSH Sound Level Meter or Bolo Finder have ads?
Which is updated more often, NIOSH Sound Level Meter or Bolo Finder?
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