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Say you want to watch TV with friends or family. Adjust the TV volume to a level comfortable for everyone, then launch Petralex and create a new profile for that room. Point the phone's microphone toward the TV — now you can enjoy the show at your own volume without disturbing anyone.

Yes! Create a dedicated profile for that venue. Switch the microphone to "Microphone in phone/tablet" mode, hold the device in your hand or set it on a surface pointing toward the sound source, and activate the profile when you arrive.

Petralex works with Bluetooth headsets, but the quality may differ from wired headsets due to factors specific to each device: supported Bluetooth profiles, transmission delay, and microphone access depending on your phone model and Android OS version.

Tip: before buying a Bluetooth headset, check your smartphone's compatibility list and the manufacturer's delay specifications.

Petralex can significantly improve speech intelligibility in different acoustic environments. It was tested successfully on users with first and second-degree sensorineural hearing loss. However, the app is not a certified medical hearing aid. If you try it (it's free!), please share your experience in the reviews.

Each acoustic environment is different. Create a separate profile for the café — run the hearing test there and save it. Petralex lets you switch between profiles quickly, so you can always have the right one active for the right place.

No. Petralex uses non-linear amplification — quiet sounds and speech are amplified according to your personal profile, while loud sounds stay at the same level. It's smart compression, not just a volume boost.

This usually happens when the phone volume is at maximum and Acoustic Feedback Suppression is on — which causes white noise to be amplified. Try turning the volume down slightly and reducing the microphone sensitivity in Settings.

This is related to how your hearing perceives sound. Try these fixes:

• Switch between the four amplification formulas: NAL, Berger, POGO, Petralex
• Adjust high and low frequency amplification levels manually in Settings

These are different amplification prescriptions used in audiology. NAL, Berger and POGO are the most widely used international standards. Petralex is a proprietary formula developed specifically for this app. Try each one to find what sounds best for you.

That's acoustic feedback — it happens when the microphone and headphones are too close together. Enable Acoustic Feedback Suppression in Settings. If you're not using that feature, keep some distance between the headphone speaker and the microphone.

For distant sound sources (more than 3 metres away), use the phone's built-in microphone and point the bottom of the device toward the speaker. This gives Petralex a cleaner audio signal to amplify. You can also fine-tune volume using the in-app slider or your phone's volume buttons.

No. Petralex is a Personal Sound Amplification Product (PSAP) — not an OTC hearing aid. In the United States, a 2022 FDA ruling created an over-the-counter hearing aid category that allows adults with mild-to-moderate hearing loss to buy FDA-classified hearing aids without a prescription. Petralex does not belong to that category. It is designed to amplify environmental sounds in everyday situations and is not intended to compensate for hearing impairment. If you suspect hearing loss, consult an audiologist.

Petralex runs on any device with iOS 13 or higher — iPhone, iPad, and iPod touch.

Yes — enable iCloud sync in the app settings on both devices and your profiles will transfer automatically.

Note: transferred profiles should only be used with the same headset you used during the original hearing test.

Yes, Petralex fully supports AirPods and other Bluetooth wireless headphones. Note that Bluetooth introduces a small audio delay compared to wired headsets — this is normal. For best latency results, wired earphones are recommended.

Petralex works on all Android devices running Android 5 or higher.

Audio delay depends on your device's hardware. Some Android models introduce more latency than others. For minimal delay, use a wired headset rather than Bluetooth. If you're seeing a large delay with wired headphones, your device's audio chip may have higher processing overhead — this is a hardware limitation.

If Petralex doesn't appear for your device, it means we haven't yet verified full compatibility with your model. Please contact us at [email protected] with your device model and Android version — we'll investigate and work on making it available.

1. Go to Settings → [your name] → iTunes & App Store
2. Tap your Apple ID at the top → View Apple ID
3. Tap Subscriptions
4. Tap Petralex → choose a new plan or tap Cancel Subscription

Your subscription stays active until the end of the current billing period. Apple support article ↗

1. Open the Google Play Store on your Android phone
2. Tap Menu → Subscriptions
3. Find Petralex and tap it
4. Tap Cancel subscription and follow the prompts

Important: uninstalling the app does NOT cancel your subscription. You must cancel it manually to stop being charged. Google Play support article ↗