I'd recommend train sounds since they have a interesting rhythm and there's no music. With regard to Music, it is haram as pointed out by the other brothers. you can try this app tho:
https://play.google.com/store/apps/details?id=com.peakpocketstudios.atmosphere
it has nature sounds like train, rain, birds etc
I would recommend reading:
An Authenticated Summary of the Prophet’s (Peace and Blessings of Allaah be upon him) Prayer by Haafidh Zubayr 'Ali Za'i.
in addition to studying the Quran and what the brother said.. basically worshipping Allah boosts your iman.. especially in ramadhan.. make a pact that you will pray (5 fardh obviously) all the sunan al rawatib (authentic sunnah prayers) and as much qiyam (taraweeh, tahajjud) as you can.. even if only 2 rakaat.. do alot of azkaar, especially morning evening (you will find all authentic ones in hisnul muslim give lots of charity..
and along with all that.. read this small booklet called Weakness of Faith