Boiling heat transfer (BHT) is a promising technology for cooling next-generation electronic devices because it can remove a high heat flux using latent heat. In comparison with single-phase forced convective cooling, BHT needs no powerful pump, resulting in eco-friendly cooling system because of reducing the pumping power. In particular, microbubble emission boiling (MEB) is a key for cooling a higher heat flux than the ordinary critical heat flux (CHF). MEB is observed in highly subcooled condition. In MEB, many small bubbles are emitted from the coalescence bubbles on a heat transfer surface. Although MEB can remove a heat flux of above 10 MW/m² at atmospheric pressure, the mechanism of the onset of MEB has not been revealed yet. Therefore, there is research to study the mechanism of MEB with measuring the boiling bubble behavior using a high-speed camera and analyzing the boiling sound through fast Fourier transform (FFT) technique. However, the previous MEB studies used a copper heat transfer surface. It is known that a copper surface is easy to oxidize in subcooled pool boiling at atmospheric condition because the oxygen existed in air dissolves in the subcooled water. As a result, the wettability of the copper heating surface was changed, which affects to the boiling bubble behavior. To experimentally investigate the behavior of boiling bubbles, in this study, the authors have conducted subcooled pool boiling using deionized water to exam the boiling sound using a hydrophone in nucleate boiling regime and MEB regime. To obtain a stable surface for subcooled boiling test, a black chromium coated copper surface is used for the heat transfer surface. Consequently, the experimental result found that the peak frequency of the boiling sound is varied by the liquid subcooling. In addition, the effect of the surface wettability on the boiling sound was investigated.