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Directivity of speech and singing is determined primarily by the morphology of a person, i.e., head size, torso dimensions, posture, and vocal tract. Previous works have suggested from measurements that voice directivity in singing is controlled unintentionally by spectral emphasis in the range of 2–4 kHz. The attempt is made to try to identify to what extent voice directivity is affected by the mouth configuration and the torso. Therefore, simulations, together with measurements that investigate voice directivity in more detail, are presented. Simulations are presented for a piston in an infinite baffle, a radiating spherical cap, and an extended spherical cap model, taking into account transverse propagation modes. Measurements of a classical singer, an amateur singer, and a head and torso simulator are undertaken simultaneously in the horizontal and vertical planes. In order to assess differences of voice directivity common metrics, e.g., horizontal and vertical directivity indexes, are discussed and compared to improved alternatives. The measurements and simulations reveal that voice directivity in singing is affected if the mouth opening is changed significantly. The measurements show that the torso generates side lobes due to diffraction and reflections at frequencies related to the torso's dimensions.

Head related transfer functions (HRTFs) describe the physical path from an acoustical source to the ears. It can be gained within the relation of two measurements. The first will give the reference sound pressure in the virtual middle of the head the second has to be done in both ears. In literature exhaustive investigations concerning the idealized location of the second position can be found. Beyond that measurements with various artificial heads and human-beings considering various source directions (azimuth and elevation) with different angular resolutions have been undertaken. The obtained HRTFs exhibit, with subject to the examined source position, frequency dependent magnitude and phase. These complex transfer functions are caused by various reflections, diffractions, pressure superelevation, and shadowing, respectively. Reflections are caused form pinna, head and torso, too. Heretofore during determination of the transfer functions the influence of various head-torso arrangements have not be considered. Within this paper the differences which will be caused due to different head-torso angles will be highlighted. Beyond that a numerical model based on interpolation using spherical harmonics will be presented. By the aid of that model the integration within an existing binaural resynthesis model can be realized and perceptual differences within a dynamic system can be investigated.

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This article presents a new database of speech produced under cognitive load for the purpose of non-invasive psychological stress monitoring. The voices and the heart rates of eight airline pilots were recorded while completing an advanced flight simulation programme in a level D full flight simulator. Focusing on real-world applicability, the experiments were designed to yield the maximum degree of realism possible. Evaluation of physiological reference measures in pilots demonstrates that several heart rate variability parameters correlate with speech features derived from the recorded data. The article discusses the evolution of speech monitoring in aviation and proposes that applicationorientated research methods can be useful in designing a system for real-world monitoring.