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.