Let’s make one more circle on the central part of the picture, the same way it is shown next image:



Blending Options>Gradient Overlay:

 

 



Blending Options>Drop Shadow:

 



The loud speaker is finished. The only thing we have to make also is turning it tight with screws. Let’s start creating them. Create firstly a circle the way it is shown next image:



Blending Options>Gradient Overlay:

 

 



Blending Options>Stroke:

 



The Pen Tool (P) will be helpful in picturing an octagon: