The occurrence of oscillating combustion and combustion instability has led to resurgence of interest in causes, mechanisms, suppression, and control of flame noise. Nonpremixed flame noise is low frequency and difficult to control using conventional acoustic liner and so significant noise reduction needs to be achieved by altering the source. Noise generated by enclosed flames is of greater practical interest but is more complicated than the noise generated by open flames, which itself is not clearly understood. Improved understanding of the noise generated by open flames is attempted by studying spectral content of the sound for flames for which detailed velocity, scalar property, and radiation measurements are available in the literature (International Turbulent Non-Premixed Workshop flames; http://www.ca.sandia.gov/TNF/abstract.html). Comparisons were made with the spectral content of sound generated by air jets at identical Reynolds numbers. The spectral sound pressure levels (SSPL) generated by the flames were higher than those generated by corresponding air jets at all frequencies. The differences between the SSPL were the highest in the relatively low-frequency range of 400-2000 Hz. The flames emanate a constant SSPL in this frequency range for locations near the axis. The width of this range decreases at larger radial locations. The effects of flow velocity are stronger at higher frequencies. The spectra show substantial reduction in highfrequency components away from the burner exit, especially in the axial direction. These observations can be used for designing combustors with lower noise and also in the evaluation of computational aeroacoustics codes.