It’s only fair to say that this is fairly narrow in terms of its range of interest, and that it does intersect with my interests on two counts, firstly around field recordings and found sounds, and secondly because I visited Porto a couple of years ago and really liked it there.
Anyway, here are the details of the app, it’s free on the app store so you might want to take a look.
“PORTOphone is a music application that enables the use of of Porto sounds in a musical way, making a combination of illustrations of our iconic locations with sounds recorded on site. In addition to the ambient sounds, the PORTOphone also allows you to hear a set of peculiar and typical expressions recorded in the oldest areas of the city. With this tool we can create our own soundscape from the sounds of the city of Porto.”
PORTOphone app on the app store (free):