Hard to think when hearing audible speech I don't know what is the exact cause of this but when there is some song playing around me or someone is talking near me its harder for me to concentrate my thoughts or imagine something. However pure instrumental music is fine

I am a frequent video game player where you need to keep listening to enemy movements and to keep track of their positions. 

Playing games like that has led me to be able to operate without concentrating all of my senses on one thing. Like I can do do something carefully by my hands looking at it and at the sane time hear what people are talking about around me, often involuntarily.

But this means when someone talks or a song plays with recognisable speech in it then my concentration involuntarily shift to the audio and it's harder to concentrate on my thoughts. I have to put effort to ignore the sound and keep at my thoughts. 

What is this phenomenon called?
There are many things at work here. A lot of your sensitivity to human voice can be attributed to the tonotopic organization of the basilar membrane. Check out this image of the cochlea and notice how its sensitivity to different frequencies does not decrease linearly over space https://media1.britannica.com/eb-media/98/14298-004-99934987.jpg , this entails that we are most sensitive to frequencies in the 2-4kHZ range, which significantly overlaps with the frequency range of human speech https://users.cs.cf.ac.uk/Dave.Marshall/Multimedia/node271.html .

There is also evidence for using a network of domain specific mental processes to do complex tasks like navigating a room. Specifically, it seems that linguistic processes make spacial navigation tasks easier(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3572715/ ; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2745626/) --if this is true we could predict that overloading someone's linguistic capabilities by, say, speaking to them, would make spatial navigation tasks harder, which could explain how some stimuli can be "less distracting" than others within different contexts.