This paper faces two problems: (1) the comparison of two different technologies for the characterization of acoustic propagation patterns and the positioning of acoustic sources in tangible acoustic interfaces (TAI) and (2) the usability evaluation of two different prototypes of TAI. In the framework of the EU-IST project TAI-CHI (Tangible Acoustic Interfaces for Computer-Human Interaction), two different prototypes of tangible acoustic interfaces have been designed, based on the TDOA (Time Delay Of Arrival) and the TR (Time Reversal ) approaches. The developed TAI prototypes have been presented and evaluated during a public event held in Genova from the 25th to the 29th of july 2005, the first S2S2 EU Summer School, organized by the EU IST Coordinated Action S2S2 – Sound to sense, sense to sound (www.s2s2.org). In this context, a group of participants had to compile a questionnaire, provided by GERG, Department of Psychology, University of Genève). GERG carried out a statistical analysis of the collected data and provided the results and the interpretation presented in this paper, in terms of comparison of the two TAI prototypes and of which usability dimensions are of most importance for the users.