Comparison

Sound Level & Spectrogram vs KFEI CSViewer

Price, ratings, monetisation and update history for both apps, side by side โ€” with what reviewers say about each.

Head to head
About

Sound Level & Spectrogram

Measure sound levels in decibels and visualize sound frequencies with a real-time spectrogram. Understand your environment's noise and protect your health. Offers advanced settings for accurate acoustic analysis.

Highlights
  • Sound level measurement (dB)
  • Real-time spectrogram analysis
  • Frequency weighting correction (A, C, Z)
  • Time weighting characteristics (Fast, Slow)
  • Time course graph
  • Environmental noise measurement
Read full description

"Sound Level & Spectrogram" is a sound level meter app for iPhone to easily measure the sound level of noise and music in your living environment. Simply tap the start button to measure sound levels in decibels (dB) and view the real-time variation of the sound level. You can also use the spectrogram feature to visually check the frequency characteristics of the sound source. Furthermore, you can select between frequency weighting correction characteristics and time weighting characteristics, which are essential for standard sound level meters, enabling appropriate sound measurement. Exposure to noise can impact health, potentially causing tinnitus, sleep disorders, stress, cognitive decline and heart disease. These risks have also been highlighted by the World Health Organization (WHO). Understanding noise levels is the first step towards improving your quality of life. Use this app to protect your health and create a comfortable living environment. Features: - Sound level measurement (dB): Leq (equivalent sound level), Min (minimum value), Max (maximum value), Avg (time-averaged equivalent sound level) - Frequency weighting correction characteristics: A (general sound level measurement with auditory correction), C (sound level measurement with almost flatter correction than A correction, e.g. peak evaluation at high volume), Z (flat characteristics without auditory correction, physical sound level measurement) - Time weighting characteristics: Fast=0.125sec, Slow=1.0sec - Time course graph - Spectrogram: 1/3 octave band analysis - Measurement time: 20 sec Applications: - Environmental noise measurement - Architectural acoustics - Live sound check - Installation of audio equipment - Tuning of sound equipment - Device management Example of the noise level situation: - 130 dB: Engine sound of Airplane - 110 dB: Horn of Car - 100 dB: Noise of passing train - 90 dB: In loud factory - 80 dB: In the train, Vacuum cleaner - 70 dB: Noisy office, Noisy Street - 60 dB: Quiet Car, Normal conversation - 50 dB: Quiet office - 40 dB: In the library, Quiet residential area - 30 dB: Outskirts of midnight, Whisper - 20 dB: Sounds of rubbing leaves Note: - Spectrogram is a tool to analyze the frequency spectrum of sound, with time on the horizontal axis, frequency on the vertical axis, and the strength of the signal represented by colors, and is used for acoustic analysis, voiceprint identification, etc. - This app is adjusted the reference value for iPhone. However, the built-in microphone of your iPhone is likely to have a non-uniform gain. Therefore, exact measurements are not guaranteed. - The standard noise measurement range is 30-130 dBA, and the measured value (Leq) is about 30 dBA in a quiet room of the household. Due to the presence of background noise, noise levels are never measured at 0dBA even in very quiet environments. In a typical anechoic room, the noise level is around 5-15 dBA. - At the initial startup after installing the app, the iOS system asks for permission to access the built-in microphone. In this case, you need to enable access to the microphone. If you have not enabled this setting, this app cannot work by privacy restrictions of the iOS system. Please enable the access permission on the iOS setting, "Settings > Privacy & Security > Microphone". Please visit our iOS app support page for more information on this app.

About

KFEI CSViewer

Read full description

This application displays the results of Channel Sounding, which measures the distance between two Bluetooth devices. It also allows you to configure an offset for the displayed results.

Screenshots

Sound Level & Spectrogram4 screens
KFEI CSViewer2 screens

Verdict

The call

The clearest difference is ads: KFEI CSViewer at none against Sound Level & Spectrogram's shown. KFEI CSViewer also leads on update cadence (every 5 days vs every 5 months). On price, in-app purchases, device support and iOS requirement there is nothing between them.

Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Sound Level & Spectrogram ships an update every 5 months, KFEI CSViewer every 5 days. The most recent releases landed on October 6, 2026 and October 17, 2026 respectively.

Scorecard2 real differences ยท 6 level
Sound Level & Spectrogram versus KFEI CSViewer: the parameters behind the verdict, then further details
ParameterSound Level & SpectrogramKFEI CSViewer
PriceFreeFree
Positive reviews100.0% of reviewsโ€”
Update frequencyEvery 5 monthsEvery 5 days โ€” better
AdsYesNo โ€” better
In-app purchasesNoNo
MonetizationAd-supportedโ€”
DevicesiPhoneiPhone, iPad โ€” better
Requires iOS18.717.6 โ€” better
Further details โ€” not scored
Size4 MB3 MB
Age rating4+4+
DeveloperTOON,LLCKAGA FEI Co., Ltd.

In-app purchases

None

Sound Level & Spectrogram

No in-app purchases

None

KFEI CSViewer

No in-app purchases

Questions

Is Sound Level & Spectrogram free?
Sound Level & Spectrogram is free to download, with no in-app purchases.
Is KFEI CSViewer free?
KFEI CSViewer is free to download, with no in-app purchases.
Do Sound Level & Spectrogram or KFEI CSViewer have ads?
Sound Level & Spectrogram shows ads; KFEI CSViewer does not.
Which is updated more often, Sound Level & Spectrogram or KFEI CSViewer?
Sound Level & Spectrogram ships an update every 5 months, and KFEI CSViewer every 5 days. Most recently, Sound Level & Spectrogram was updated on October 6, 2026 and KFEI CSViewer on October 17, 2026.

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