| Abstract [eng] |
There are developed many different means and methods helping the blind to orientate in the environment and to avoid obstacles on the road. Still, the most popular is a white cane. Its popularity is influenced by low cost and simplicity, but it provides very limited amount of information – obstacles are detected maximum at 1.5 m distance. Besides tactile sense, the blind often relies on spatial sounds. One of the ways helping the blind to orientate in the surroundings is to make sounds with the tongue, fingers or hit the floor with the cane, thus echo is generated, which allows for the experienced blind to estimate approximately how far and in which side the barrier is. This method requires long training and practice. Knowing that hearing of blind people is more acute compared to healthy ones, it is possible to use spatial sound when designing electronic orientation and obstacle detection systems for the blind. Today the market does not offer systems that would make the most of the blind acute hearing. The aim of this work is to investigate the human ability to detect the direction of the sound source in horizontal and vertical planes and to estimate the distance to it, also to overview possible errors and to evaluate the possibility of using the spatial sound for obstacle identification. In order to simulate the spatial sound, that would give the most accurate information, it is necessary to collect data on the changes that occur in the audio signal, as it travels from the sound source to the ear canal. These changes are the result of human head and ear shapes and are called head related transfer functions (HRTF). Head related transfer functions are recorded during the research performed in an acoustic room. When HRTF functions are obtained, there are performed tests with the experiment participants, on distinguishing the spatial sound location. |
