FIELD: medicine.SUBSTANCE: group of inventions refers to medicine. Implementing a method for noise frequency ranging and a method for diagnosing cardiac diseases involves recording phone cardiograms from the first group of healthy subjects and the second group of the second group of patients suffering the above cardiac diseases. A normal frequency sample and a maximum threshold frequency are determined to derive a finite collection of the sampled frequencies. Spectral energies at all the sampled frequencies and spectral energies at all the frequency ranges are calculated. The above spectral energies of all the frequency ranges are compared. A frequency range enabling a maximum difference of the spectral energies of the phone cardiograms from the first and second groups of phone cardiograms is determined. The above energy of the specified frequency range of the phone cardiograms of a patient is compared to the energy of the related frequency range of the first and second groups of the phone cardiograms to state if the patient suffers a cardiac disease. A device for implementing the method comprises a phone cardiogram recorder, a phone cardiogram data collector, an output medium, a processor and a set of instructions for implementing the method. A machine-readable medium of a programmable device comprises the set of instructions for implementing the method.EFFECT: group of inventions enables providing the automated diagnosing of cardiac failure in children ensured by studying the heartbeat energy.14 cl, 9 dwg, 3 tblГруппа изобретений относится к медицине. При осуществлении способа определения диапазона частот и способа выявления заболеваний сердца осуществляют регистрацию фонокардиограмм первой группы от первой группы здоровых пациентов и второй группы от второй группы пациентов, страдающих указанным заболеванием сердца. Определяют норму частотной выборки и максимальную пороговую частоту, получая конечную совокупность отобранных частот. Вычисляют спектральные энергии
