Meeting Topic: Front back binaural confusion experiment with acoustic divergence
Moderator Name: Leandro E. Rodríguez
Speaker Name: Federico Lorenzo Martin, Ignacio Speranza, Christian Tritz
Other business or activities at the meeting: Planning the experiment with acoustic convergence (October 25)
Meeting Location: Buenos Aires
We reunited in Studio 1 in order to make sequences of experiment trials focusing on the perception of binaural signals with front or back directivity. The stimulus were recorded previously in the ECOS semi-acoustic chamber (human speech, snare drum, pink noise burst, homemade wind chimes with keys) and were convolved with the BRIR's obtained from an octophonic setup in our Studio 2.
Doing the trials in other studio gives us the chance to make a study of the effects of the acoustic divergence on the subject responses (front, back, omni, inside the head). The section members who were part of the Binaural group were the subjects, with exception of the faculty advisor who commanded the trials. Additionally, a not sighted student from our school, María Paz Boffi, acted as a subject too. Her participation gives us and additional item in order to discard the visual clues (room size and characteristics, subject location, distance from lure source —a Genelec 1031A monitor-) in at least one trial. Thanks María Paz! She will be soon part of us becoming an AES Member...
The trials were composed by convolutions of their own HRTF's and of the others, in other to make comparisons. Each subject has four files: subject name front, subject name back, subject name front with filter, subject name back with filter. The stimuli with filters were composed of the ones proposed by Yao, S. N. & Chen, L. J. (2013). HRTF adjustments with audio quality assessments. Archives of Acoustics, 38(1), 55-62. We used closed headphones (AKG K44) and an additional and unique pseudo-omni stimulus (the front and the back together), with the HRTF of the Faculty Advisor.
We also have the privilege of having the presence of an almost anthropology graduated from the UBA (Universidad de Buenos Aires - Buenos Aires University), Dante Malaspina. Dante is using our experiences to help him to finish his career, and with his particular view from his discipline and "from the outside" gives us a lot to think in certain aspects of our work in progress. Thank you Dante!
Written By: Leandro E. Rodríguez