It has previously been established that different people attach a different meaning to the concept of "tranquil public space". A majority of persons associate tranquility with social interaction, but others associate tranquility with hearing sounds from nature or even with pure silence. Having these different beliefs and views in mind, hypotheses could be formulated on their effect on the perception and appraisal of soundscapes in urban parks. Firstly, persons associating tranquility with sounds from nature may focus more on hearing these sounds while visiting a park, and might notice them more often as a consequence. Secondly, the meaning given to tranquility also influences one's frame of reference and expectations. Thus, persons associating silence or sounds from nature to tranquility might state more easily that they hear less natural sounds and more mechanical sounds when visiting a park. These hypotheses were tested on survey and measurement data from 8 parks in Antwerp and on computational models of auditory perception. Results show that attention focusing is dominated by the change in frame of reference or expectation. In addition, a weak relationship was found between the park where persons were encountered and their view on the concept of tranquility.