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This paper analyses the performance of Differential Head-Related Transfer Function (DHRTF), an alternative transfer function for headphone-based virtual sound source positioning within a horizontal plane. This experimental one-channel function is used to reduce processing and avoid timbre affection while preserving signal features important for sound localisation. The use of positioning algorithm employing the DHRTF is compared to two other common positioning methods: amplitude panning and HRTF processing. Results of theoretical comparison and quality assessment of the methods by subjective listening tests are presented. The tests focus on distinctive aspects of the positioning methods: spatial impression, timbre affection, and loudness fluctuations. The results show that the DHRTF positioning method is applicable with very promising performance; it avoids perceptible channel coloration that occurs within the HRTF method, and it delivers spatial impression more successfully than the simple amplitude panning method.

This paper focuses on aspects of implementation of moving virtual sound source in virtual auditory environment. Rendering of dynamic source based on use of Head-Related Transfer Function is achieved by application of filtering with varying impulse response of the filter. This algorithm may be in its essence implemented by several methods, where each approach provides slightly different output signal resulting in variance of perception of spatial fidelity. The main difference results from different output of linear and circular convolution usually implemeted in such processing. Particular variants are described, discussed and compared by subjective listening test of the positioned signals. Other aspects of implementation as artifact occurrence are also discussed.

ResumenEste artículo describe las opciones de crear un Espacio Acústico Virtual para propósitos de navegación de personas invidentes en un ambiente desconocido. La idea de navegación acústica está basada en el uso de sonidos posicionados virtualmente a través de audífonos, los cuales son presentados al cliente a través de un operador de cámara. Esta propuesta requiere una mirada cercana al efecto de movimiento de la cabeza y habilidad del operador de cámara para guiar al cliente con los estímulos sonoros para evitar los obstáculos existentes. El presente artículo continúa con la anterior investigación, extiende los primeros resultados y sugerencias y descubre nuevos aspectos para ser analizados. Posicionamiento de fuente sonora virtual en navegación para personas invidentes Virtual Sound Source Positioning for Navigation of Visually Impaired Investigación 7Posicionamiento de fuente sonora virtual en navegación para personas invidentes • pp. 6-14 Palabras claveEspacio acústico virtual, navegación, invidentes, HRTF, sonorización, seguimiento de cabeza. AbstractThis paper deals with the options of creating Virtual Acoustic Space for the purposes of navigation of visually impaired people in unknown environment. The idea of acoustic navigation is based on using virtually positioned sounds presented through the headphones, which are performed to the client by camera operator. This proposal requires a closer aim on head motion effect and ability of the camera operator to lead the client by the sounds stimuli avoiding present obstacles. The presented article follows our previous research, extends first results and suggestions, and discovers new aspects necessary to be examined.