Nonlinear acoustics offers a new range of acoustic applications that are currently being
exploited. The parametric nonlinear effect—the occurrence of low frequencies with modulated
high-frequency emission—is of particular interest. This work provides a systematic exposition of the
theoretical framework on which the so-called parametric nonlinear effect is based. In relation to this
behavior is an analytical discussion of how to solve the problem for two cases: (i) nonlinear behavior
with modulation, and (ii) parametric emission of two monochromatic waves (bi-frequency). Subsequently,
parametric emission experiments were carried out in air and water using the same transducer
to compare the results with those obtained theoretically. In this sense, directivity and attenuation measurements
are obtained. Conclusively, this research offers a proof of concept for underwater acoustic
communications. It is characterized by the transmission of a binary sequence through Frequency
Shift Keying (FSK) modulation, and the subsequent decoding of each received bit (either 1 or 0)
utilizing advanced signal processing with the cross-correlation technique. This paper accentuates the
significant potential of employing the parametric effect for specialized communication applications.
