Common questions

Let’s say, you want to watch TV with your friends or relatives. Adjust your TV set to the comfortable volume, then launch the application, add a new profile and conduct the test in the room with TV on. We recommend to direct the microphone of the device to the source of sound (TV) when using Petralex. Now when you turn this profile on you can watch TV with your friends with the volume that is comfortable for everyone!

Yes, you can use it while visiting cinema, theatre or opera. We recommend you to create a corresponding profile and switch it on when watching. You should also switch the used microphone into the mode "Microphone in the phone (tablet)" and hold the device in your hand or put it on some surface in the direction of the sound source.

"The developer does not guarantee the quality of work with Bluetooth headsets will be as good as when using a wired headset. This is due to such specific features of your smartphone and Bluetooth device as: supported and not supported Bluetooth profiles in your smartphone and Bluetooth device: delay in sound transmission and playback due to specific features of connection in your smartphone/ Bluetooth device and specifics of Bluetooth profile. possible/impossible sound capture by the microphone of a smartphone depends on the model/Android OS version of your phone. Recommended: when selecting a Bluetooth headset, study the list of suitable Bluetooth devices for your smartphone and check out technical information on delays in sound transmission published by manufacturers and independent experts. "

You can use the application to improve the intelligibility of speech for different conditions of acoustic environment, but the application itself is not a hearing aid. The application was tested for patients suffering from sensorineural hearing loss with hearing disorder of first and second degrees. The results were successful, but this version of the application is not certified to be called a medical hearing aid. If you decide to try this application (it is free), please leave your review in the corresponding section and describe your experience and propositions.

Add a profile for corresponding sound environment so that Petralex can process the sound properly and make the speech more intelligible. You can quickly switch between all your profiles.

Petralex uses complex algorithms of sound processing with non-linear amplification. This means that you will hear quiet sounds and speech better while loud sounds remain on the same level. The sound in the device is equalized in such a way that quiet sounds are amplified in accordance with set parameters while loud ones remain on the same level.

You can use other products of our company to listen to music or radio. Our application PETRALEX MUSIC can be used as an audio player while PETRALEX RADIO will help you to listen to the radio.

Unfortunately, this function is not available yet. Since mobile phone manufacturers do not provide access to the required modules to external developers, Petralex cannot process the sound during phone calls. However, soon we are going to add an option of voice communication between Petralex users and telephone network subscribers.

When the volume of the phone is set at maximum and the function of Acoustic feedback suppression is on, the white noise is amplified too much. We recommend you to turn the volume down a bit and lower the sensitivity of your microphone.

This is related to psychological and physiological specifics of your sound perception. We recommend you: -To change the amplification formula being used (there are four of them in the application) - Nal, Berger, Pogo, Petralex; -Use the regulators of amplification level for high and low frequencies in Settings section.

NAL, Berger, Pogo and Petralex activate different amplification formulas. NAL, Berger, Pogo are the most wide-spread amplification formulas in the world, Petralex is a unique formula created for our application.

This is a typical manifestation of ghost effect of Acoustic feedback. It appears when microphone and headphones are too close to each other and often shows if the application is working with the headset mircophone. Recommended: the application supports the suppression of Acoustic feedback, you can activate it in the Settings section. If you are not using the function of Acoustic feedback suppression, maintain a gap between headphones and microphone.

To listen to sounds from a distant (more than 3 meters) source we recommend you to use the microphone in the phone and direct the lower part of the device (with the microphone) to the sound source. This way the application will capture, process and amplify the sound better. You can also adjust the sound volume by using a regulator in the application or by phone buttons.

No, the audiogram in the application is only used to define the suitable parameters of sound processing in a certain noise environment and cannot be used for diagnostics.

Choose the ear on which your Bluetooth headset is on now (left or right) before the test. Test your hearing for the chosen ear, save the profile, and the profile icon will show Bluetooth logo with the chosen ear (L for the left, R for the right). Select this profile when using your Bluetooth device on the corresponding ear.

Infortunadamente, el protocolo Bluetooth que se utiliza para el funcionamiento de auriculares inalámbricos en el modo de funcionamiento simultáneo con el micrófono, permite transmitir solamente el sonido mono. Complete el procedimiento de prueba en el régimen Bluetooth común (para ambos oídos, como para auriculares comunes) y utilice el perfil obtenido. En este caso en ambos auriculares se dará sonido mono. Los auriculares estéreo Bluetooth se pueden utilizar con nuestras otras aplicaciones - PETRALEX MUSIC y PETRALEX RADIO.

iOS App

The application functions on the devices with operation system iOS 9 and higher.

You can synchronize the hearing profiles on different devices. To transfer hearing profiles from one device to another activate “iCloud” in the settings of both devices.

Note: Use the transferred profiles only with the same headset/headphones that you used before.

Android App

The application works on all Android devices with operation system version 5 and higher.

The delay which shows as an echo depends on technical specifications of a phone. Further you can find information on different models of Android devices. You can find the required device in the list and find out whether it supports the Petralex application. The list of devices is regularly updated.

If the application cannot be installed on your devide, it means we do not guarantee its functioning on your phone. Please tell us what your phone model and OS version is, we will test the application and try to make it work on your device.

Manage your subscriptions

Follow the steps to view, change, or cancel your subscriptions from your iPhone, iPad, or iPod touch

  1. Go to Settings > [your name] > iTunes & App Store
  2. Tap your Apple ID at the top of the screen
  3. Tap View Apple ID. You might need to authenticate your Apple ID
  4. Tap Subscriptions
  5. Tap the subscription that you want to manage
  6. Use the options to manage your subscription. You can choose a different subscription offering, or tap Cancel Subscription to cancel your subscription. If you cancel, your subscription will stop at the end of the current billing cycle


Subscriptions on Google Play renew automatically unless you unsubscribe. If you don't want your subscription to renew, you can cancel it on Google Play. You can also change the payment method. Sometimes, you can change the subscription frequency. Cancel a subscription

  1. On your Android phone or tablet, open the Google Play Store.
  2. Tap Menu and then Subscriptions.
  3. Tap the subscription you want to cancel.
  4. Tap Cancel subscription.
  5. Follow the onscreen instructions.

Important: Uninstalling an app will not automatically stop your subscription. You must cancel your subscription to end your subscription. If you uninstall the app without canceling your subscription, you will still be charged. If an app you've purchased a subscription for is removed from Google Play, your future subscription will be automatically canceled but past subscriptions will not be refunded.