Technology

Hearing aids are traditionally produced as specialized devices with sole function of compensating hearing impairs. Complexity and limited functionality leads to camparatively high price and requires qualified personnel for device configuring and further maintenance. Various sound processing algorithms used in regular hearing aids have defined limited range of settings. These settings are picked up according to patient`s individual needs.

Recording an audiogram needs insulated study room, trained professional participation and special tone generating and amplifying equipment. Petralex applications with hearing aid functions or used for tasks related to hearing are aimed at comfortable and easy use without involvement of specialists and costly procedures.

No special qualification or equipment is needed for app configuring and fine tuning, all the settings are easy to set up with intuitive user interface. What is really important is that because of the same conditions during testing and using audiometry profiles (same sound environment, the types of headsets used, etc.) all the sound processing can be performed directly without any usually used alterations and modifications with all the individual user`s sound perception fulfilled.

Petralex applications use a broadband (without subband decomposition) hearing correction scheme. This scheme uses the wideband method of changing spectrum envelope with a finite impulse response filter. Frequency response of the filter is calculated on the basis of user’s audiogram so as to amplify frequencies at which sensitivity reduction is observed. In particular, in order to control the volume Petralex hearing aid features two functional controls: the microphone gain control and the output level control. Both the controls are external and can be used by the user depending on the acoustic environment. The gain is modified so as to provide a compression of signal in accordance with a predetermined level of hearing loss.

As all the devices, considered as app platform use stereo headsets with two speakers, binaural hearing compensation scheme with separate left/right ear sound processing was implemented.

Rechargeable power batteries and built-in microphones used in basic devices allowed applying higher than ordinary hearing aids use sampling rate of 44,1 kHz. Higher sampling rate makes pass- band wider up to 16-20 kHz, than common 10 kHz range for ordinary digital hearing aids. That gives broader sound range audibility to users compared to regular hearing aids that cannot process wide pass-band due to sampling rate limits.

Regular hearing aids technology is based on processing sound with specially designed CPUs at frequencies equal or proportional to sampling rate frequency. Increasing processing frequency leads to higher power consumption, what is shortening battery life. That`s why all hearing aid engineers and developers always have to choose higher pass-band or longer battery lasting for their devices. In common terms broad pass-band means expanding range of audible tones beyond ordinary hearing aids capabilities. Now Petralex users can hear slightest sounds, such as nature ambient soundings and much more.

Technological advantages of PETRALEX® applications on mobile platforms

large, visible and easy to use interface buttons and controls suitable to any user; fast pre-saved profile selection and new profile creating features for any sound environment now are directly accessible in application interface;
the user can choose different models of headsets and headphones, including various sizes of the speakers which, together with rechargeable batteries, can achieve the maximum sound pressure level, comfort of use and sound quality; the user of Petralex applications on the basis of mobile devices (smartphone, tablet) does not experience any psychological inconvenience, because this type of devices is not associated with any hearing pathologies; long operating time without batteries charging.
the implementation of Petralex applications on the basis of mobile devices allows its users to choose the gain and compression settings fully matching the user- defined variants of sound environment and personal feelings of listening comfort, which is advantageous in comparison with the universality and permanence of hearing loss compensation parameters of specialized hearing aids;
unification of operating systems and the mobile device characteristics has also allowed to implement the possibility of quick migration not only between different devices with the same type of operating system - iOS or Android using the cloud storage services iCloud and Dropbox, but between Petralex applications as well as.
When using the service, the saved user audio profiles automatically become available to all devices and Petralex applications connected to a personal data storage by the user;
All kinds of modern headsets wired or wireless, located directly in the ear and using the functional advantages and the natural acoustics of the outer ear or the overhead headphones are relatively inexpensive, so the risk of damage from earwax and moisture is not as critical as for the specialized hearing aids.