## 4 Conclusions  
The aeroacoustic sources of human voice production are investigated based on a validated voice model. Including the convective part of the source term yields the most accurate results. The error is reduced by 0.6% compared to the validated model [18]. Neglecting convective source effects yields in lower accuracy, but overall the convective term can be neglected for human phonation providing a potential of a reduction of computational effort and resources. Firstly, the Fourier transformed sources let us conclude where we find dominant sources for a specific frequency. Regarding the local pressure time derivative at the base frequency and the lower frequency harmonics, the acoustic sources are found in the supraglottal area. At higher harmonics and non-harmonic frequencies, the dominant sources are located mainly in the area of high fluid velocity, being inside the glottal jet and in areas of turbulent structures. Secondly, the temporal evolution is connected to the source field concerning characteristic time steps that are connected to the VF movement. In the case of opening vocal folds, the flow is accelerated and turbulent structures are blown out of the region between the false VFs. A new glottal jet is formed when opening the VFs. This process continues until the VFs are fully open. In the case of fully opened VFs, a well-developed glottal jet is present. From this time instance on, the VFs are closing and restrict the glottal gap. This constriction diffuses the velocity jet and the structures start to fade out. Strong fluctuations are caused by the decelerating fluid. In the case of fully closed VFs, the vortices are decaying and are localized in a resting fluid. Because the flow is cut off, the driving energy of the flow is zero and the flow starts curling. Since most voice disorders are a combination of mechanisms that prevent the VFs from closing the glottal gap, the occurring effects on the voice can be partly explained by the discussed time instances. From these findings, we can learn how vocal fold disorders transform into specific characteristics of the aeroacoustic sources. From these findings, we can learn how pathological effects on the vocal folds transform into specific characteristics of the aeroacoustic sources. Since most voice disorders are a  
Figure 19: Sound pressure level of simulations using \(\partial p^{ic}/\partial t\), the convective part, and the full PCWE source term as acoustic source in comparison with experimental measurement data at a microphone positioned 1m from the end of the vocal tract (see [18]). combination of mechanisms that prevent the VFs from closing the glottis, the occurring effects on the voice can be partly explained by the discussed time instances. We learned that if the gap is narrow, the pressure gradient term is large and dominates the visualization but is not contributing to the sound spectra to a large extend (0.6% accuracy increase). If the glottal gap is widened, the peak of the convective term is reduced significantly. For a fully open glottis gap, the convective part and the time derivative part have a similar magnitude. Finally, we have to note again that the convective effect dominates the source visualization of the PCWE source term (simply by the magnitude between the VFs), which misleads in a possible conclusion for voice disorders. As it was reported previously, we see that the convective term is decreases with increasing insufficiency. Although this convective source term is larger in areas of the glottis gap and dominates the source visualization, its overall contribution in the acoustic spectrum is negligible. Conceptualization, S.S. and P.M.; methodology, S.S.; software, S.S.; validation, P.M., S.S., A.H. and A.W. ; formal analysis, S.S.; investigation, A.W. and S.S.; resources, M.K. ; data curation, A.H. and S.F. ; writing--original draft preparation, S.S., P.M. and A.W. ; writing--review and editing, S.S., S.K., S.F., M.D., M.K. and A.W. ; visualization, A.W.