Do I need to ask for permissions to use a sound even when it says You are free:
To sample, mash-up, or otherwise creatively transform this work for commercial or noncommercial purposes.
To perform, display, and distribute copies of this whole work for noncommercial purposes (e.g., file-sharing or noncommercial webcasting).
It does not say I need to ask for permissions in the first place.
I am talking about London Underground and British Rail sounds.
Do I need to ask for permissions to use a sound
No but it does say
Under the following conditions:
You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
You may not use this work to advertise for or promote anything but the work you create from it.
You have obviously read the Legal page so go ahead. Contributors do appreciate knowing what their sounds end up in though, so it is only polite to let them know.
Hope this helps.