# Sound Level & Spectrogram vs KFEI CSViewer

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.

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

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.

## The numbers

| Metric | Sound Level & Spectrogram | KFEI CSViewer |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | Every 5 months | **Every 5 days** |
| Monetization | Ad-supported | — |
| Size | 4 MB | 3 MB |
| Requires iOS | 18.7 | **17.6** |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [TOON,LLC](https://appshunter.io/developer/633948723) | [KAGA FEI Co., Ltd.](https://appshunter.io/developer/1635192113) |

## What reviewers say

### Sound Level & Spectrogram

[App page](https://appshunter.io/ios/app/sound-level-and-spectrogram/id6503722682)

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

**In-app purchases:** none


### KFEI CSViewer

[App page](https://appshunter.io/ios/app/kfei-csviewer/id6771185904)

**In-app purchases:** none


## Frequently asked 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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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*