Follow below mentioned steps to make sound on scratch.
Firstly, click on my stuff.
Then, you click on + New Project.
Next, you choose a sprite. To do this you have to hover on the choose a new sprite, and you can either draw, upload, or choose a sprite given.
After you have your sprite, you have to drag the when sprite clicked bar, which is in the Control section.
After that, you have to go to the sound section and get the start sound. On this image, it will say meow as I chose the normal sprite. If you want to play a sound until something is done, you drag the play sound…. until done. If you want to stop a sound you have to get the stop all sounds bar. You can also stop the sound after a limited amount of time, you have to get to the Control section and get the wait 1 secs bar. If you want to put it for a specific amount of time, you click on the 1 and put any number you want.