## 1 Introduction  
Generation of the human voice is a highly complex biophysical process, where the viscoelastic multi-layered tissues of the vocal folds interact with the airflow expired from the lungs, start to self-oscillate and close the channel periodically. The vocal fold oscillation and glottal closure modulate the mass flux, create complex turbulent structures and pressure disturbances, which form the voice source. This source signal is modulated by the vocal tract, radiated from the mouth, and is perceived as a human voice. The physiological principles are well described in the monograph by [PERSON] [1]. The acoustic resonances of the subglottal spaces (trachea, bronchi, and bronchioles) and supraglottal part (the vocal tract) can enhance the driving pressures of the vocal folds and the glottal flow, thereby modifying the energy level of sound sources. The voice generation is governed by a three-way interaction between the structure, airflow and acoustics. The dominant aeroacoustic sound sources are located within the glottis and the supraglottal region. Three characteristics of flow-induced sound are defined in terms of free-field radiation--first, vocal fold oscillation induces a monopole radiation pattern. Second, the interaction of the vocal folds and the air jet creates surface pressure fluctuations that radiate like a dipole. Third, the turbulent structures located downstream of the glottal constriction have a quadrupolar radiation pattern [2; 3]. The sound due to turbulence has a significant influence on the broadband noise at higher frequencies. The principles of voice generation may be studied by in vivo, excised larynx or synthetic vocal fold measurements [4; 5], or by numerical modelling. During recent decades, numerical simulation of human phonation has advanced considerably towards a state where full-scale aeroacoustic simulations on realistic computed tomography (CT)- or magnetic resonance imaging (MRI)-based geometries are possible. It can be anticipated that soon these simulations could be used for subject-specific pre-surgical predictions of vocal fold oscillations and resulting voice quality for people suffering from various vocal fold dysfunctions [6; 7] or for the development of vocal fold prostheses. However, though powerful numerical simulation tools are available, the numerical methods still face challenges due to the nonlinear phenomena both in solid and fluid mechanics. This study focuses on the impact of the numerical approach to turbulence modeling on the aeroacoustic simulation of voice generation. Turbulence is an inherent property of medium and high Reynolds number flows, where the energy of the large flow structures is transferred in a cascade of scales towards the smallest vortices, where the turbulent kinetic energy dissipates into heat. Measurements on excised canine larynges suggest that the airflow in trachea, subglottal and intraglottal space is typically laminar, but encounters transition to turbulence shortly downstream of the glottis [8; 9; 10]. The vortex dynamics in the supraglottal spaces and vocal tract are governed by turbulent momentum transfer. Turbulence also induces a broadband sound source, which is important especially in the case of breathy phonation, but is also significant in the case of modal voice [11]. In the computational fluid dynamics (CFD) of turbulent flows, three approaches are used. First, the Direct Numerical Simulations (DNS), that is, straightforward discretization of the Navier-Stokes equations on a sufficiently fine computational mesh, where all turbulent scales up to the smallest dissipating vortices are resolved. Even for moderate Reynolds numbers encountered in laryngeal airflow, this type of simulation is prohibitively expensive in terms of computational requirements. Sometimes, the term \"laminar simulation\" is, somewhat incorrectly, used for a DNS of flow using a coarse mesh. This is correct for purely laminar flow with no turbulence.