There are many ways to isolate vocals from a song. The results vary and can rather depend on your source material. For example if you have an instrumental of the same track you can “invert” that against the original. Mathmatically speaking, it’s the original (with vocals) minus the instrumental (without vocals) equals the vocals. And this effects can be done easily on open source (free) software such as Audacity
If that fills you with dread then don’t be put off – there is a much simpler way. Whilst the result won’t be perfect, this method will certainly allow you a rough separation of vocal and instrument without the need for the instrumental track and as easy as clicking a button. The algorhythms (yes deliberate misspelt pun) on Fadr.com are pretty impressive. Not only can it split vocals from drums, guitar and keyboards into 4 different stems, it also tells you the key of the chord being played and attempts (far from perfect mind) to convert them into midi tracks to help you get started on your DAW (Digital Audio Workstation)
If you’re a budding amateur muso like myself, you will be fascinated to listen to the accompaniment of many tracks without the distraction or noise of the singer. Also perfect for remixes. Free to sign up. Have a play and try not to get addicted.Fadr
I love a good instrumental as one of my Spotify playlists demonstrates.