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Development of common HRTF and evaluation of virtual elevation effect
For multi-channel surround sound system, elevated sound contents (usually perceived from upwards such as helicopter noise, birdsong, airplane noise, etc.) can recently be generated by actually elevated sound channels. Various speaker configurations such as Dolby 9.1 channel surround sound, Samsung 10.2 channel vertical surround sound, and NHK 22.2 channel surround sound adopted ¡°height channels¡± to generate such elevated sound contents and have provided more realistic, vertical sound impression to listeners. Those multichannel surround sound layouts might be speaker configurations of multi-channel surround sound system in near future. Until now, however, increasing the number of additional speaker channels and installing height speakers on the ceiling are desired to avoid in a practical point of view. If one can virtually generate a sound impression induced from height channel by utilizing widely used ear-level loud speakers such as conventional 5.1 channel surround sound configuration, abovementioned impracticality might be solved through a simple signal processing technique.

In this project, a novel method for generating virtually elevated sound via 5.1 channel surround sound configuration had been researched.

Fig 1. Generating virtually elevated sound via 5 speakers located at the listener¡¯s ear level.
The effect of virtually generated elevation impression was tested by comparing
real impression generated from actually elevated height speakers