OTenkeyCalc vs Sound Amplifier +
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
OTenkeyCalc
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Numeric ten keypad calculator that also displays the current temperature and weather at your current location * Weather information source: Apple Weather Service https://developer.apple.com/weatherkit/data-source-attribution/ https://support.apple.com/ja-jp/105038
Sound Amplifier +
Enhance your hearing in everyday situations. This tool uses your phone's microphone to amplify nearby sounds and deliver them to your earphones in real time. Adjust sound with an equalizer, reduce background noise, and protect your hearing with a volume limiter.
- Live audio amplification
- 3-band equalizer with presets
- Speech boost and noise reduction
- Left/right balance control
- Safe-volume limiter
- Offline functionality
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Sound Amplifier picks up the voices and sounds around you with your phone's microphone and plays them into your earphones in real time — so a soft-spoken friend, the TV across the room or a lecture from the back row comes through more clearly. Missed what someone just said? Tap Replay last 10s to hear the last 10 seconds again. Want the sound shaped for your own ears? Take the short Hearing Test and a personal EQ is built from your answers. Please note: Sound Amplifier is an everyday assistive listening tool. It is not a medical hearing aid and it does not diagnose hearing loss. LISTEN • Live amplification from 0 to +40 dB, with a live level meter • Replay the last 10 seconds — kept in memory only and cleared when you stop • Voice leveller that evens out loud and soft voices automatically • Noise reduction that cuts low rumble from air conditioning, traffic and wind TUNE • 3-band equalizer: bass, mid and treble, each ±12 dB • Presets for Speech, Music, Outdoor and Flat • A Personal preset created from your Hearing Test • Left/right balance for when one ear needs more HEARING TEST • Soft tones at 250, 500, 1,000, 2,000, 4,000 and 6,000 Hz, one ear at a time • Turn the result into a personal EQ with one tap • Hearing over time: compare later tests with your first one (changes under 10 dB are shown as no change) • Earphones or headphones are required, because each ear is tested separately MY SETUPS • Save up to 8 named setups — TV, restaurant, lecture — and bring one back with a tap SAFETY • A safety limiter caps loud peaks at a level you choose (-18 to 0 dBFS) • The app will not amplify through the phone's own speaker, where the microphone would pick the sound up again and howl • If your earphones disconnect, amplifying stops and a card explains why; reconnect them and tap Resume GOOD FOR • TV dialogue without turning the room volume up for everyone • Conversations in cafés, restaurants and family dinners • Lectures, sermons, meetings and guided tours • Birdsong and quiet sounds on a walk Tips: start with low amplification and raise it slowly. Wired earphones have the shortest delay; Bluetooth earphones work too but add a little lag. If you are worried about your hearing, please talk to a hearing professional.
Screenshots
Verdict
The clearest difference is update cadence: Sound Amplifier + at every 4 days against OTenkeyCalc's every 2 weeks. On price, ads, in-app purchases and device support 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.
OTenkeyCalc ships an update every 2 weeks, Sound Amplifier + every 4 days. The most recent releases landed on October 17, 2026 and October 24, 2026 respectively.
| Parameter | OTenkeyCalc | Sound Amplifier + |
|---|---|---|
| Price | Free | Free |
| Rating | — | 3.8 (15 ratings) — better |
| Positive reviews | — | 0.0% of reviews |
| Number of ratings | — | 15 — better |
| Update frequency | Every 2 weeks | Every 4 days — better |
| Ads | Yes | Yes |
| In-app purchases | No | No |
| Monetization | — | Ad-supported |
| Devices | iPhone, iPad — better | iPhone |
| Requires iOS | 16.7.10 | 16.4 — better |
| Further details — not scored | ||
| Size | 37 MB | 61 MB |
| Age rating | 4+ | 17+ |
| Developer | Hideaki Uchikoshi | heekyung moon |
In-app purchases
OTenkeyCalc
No in-app purchases
Sound Amplifier +
No in-app purchases
Questions
Is OTenkeyCalc free?
Is Sound Amplifier + free?
Do OTenkeyCalc or Sound Amplifier + have ads?
Which is updated more often, OTenkeyCalc or Sound Amplifier +?
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