  In the last decade, soundscapes have become one of the most active topics in
Acoustics, providing a holistic approach to the acoustic environment, which
involves human perception and context. Soundscapes-elicited emotions are
central and substantially subtle and unnoticed (compared to speech or music).
Currently, soundscape emotion recognition is a very active topic in the
literature. We provide an exhaustive variable selection study (i.e., a
selection of the soundscapes indicators) to a well-known dataset
(emo-soundscapes). We consider linear soundscape emotion models for two
soundscapes descriptors: arousal and valence.
  Several ranking schemes and procedures for selecting the number of variables
are applied. We have also performed an alternating optimization scheme for
obtaining the best sequences keeping fixed a certain number of features.
Furthermore, we have designed a novel technique based on Gibbs sampling, which
provides a more complete and clear view of the relevance of each variable.
Finally, we have also compared our results with the analysis obtained by the
classical methods based on p-values. As a result of our study, we suggest two
simple and parsimonious linear models of only 7 and 16 variables (within the
122 possible features) for the two outputs (arousal and valence), respectively.
The suggested linear models provide very good and competitive performance, with
$R^2>0.86$ and $R^2>0.63$ (values obtained after a cross-validation procedure),
respectively.
