The aim of the work is to establish the effect of tensile stresses in fiberglass on the spectra of acoustic emission signals recorded by a piezoelectric and fiber-optic acoustic emission sensor. For this purpose, fiberglass samples were made by molding using the vacuum infusion method. The samples were cut out for testing on a tensile testing machine. A fiber-optic sensor operating in conjunction with an adaptive laser holographic interferometer was glued to the surface of the working part of the samples. The piezoelectric transducer was installed on the non-working part of the sample. Acoustic emission signals were recorded by both sensors under stepwise loading with a tensile load. The result of the work is the analysis of changes in the spectra of acoustic emission signals caused by tensile stresses in the fiberglass material. It is noted that a shift in the spectrum to the high-frequency region with increasing stress is observed at low-frequency harmonics. At high frequencies that are informative for acoustic emission, the influence of tensile stresses becomes nonlinear.