Reis, TiagoCarriço, LuísDuarte, CarlosMealha, Óscar and Madeira, Joaquim and Tércio, Daniel and Sousa Santos, Beatriz2021-06-182021-06-182021978-3-03868-153-3https://doi.org/10.2312/pt.20101161https://diglib.eg.org:443/handle/10.2312/pt20101161The automatic adjustment of mobile user interfaces to the contexts in which they are used presents a possible solution for the interaction difficulties introduced by the constantly mutating characteristics of such contexts. Here we present a prototype of a portable media player. This player automatically adjusts its volume according to the users' preferences and the noise of the surrounding environment. We focus on the details of the volume adjustment algorithm and its – laboratorial and contextual - user centered evaluations. We detail the problems found on each phase of the evaluation procedure, and present a set of Wizard of Oz experiments exploring possible solutions for those problems.Mobile HCIAutomatic Volume AdjustmentsContext AwarenessUser Centered DesignContextual Evaluation10.2312/pt.2010116159-62