Let out and String out

Let out verb - Express audibly; utter sounds (not necessarily words).

String out and let out are semantically related in extend topic. In some cases you can use "String out" instead a verb "Let out", when it comes to topics like lengthen, longer.

String out verb - Set out or stretch in a line, succession, or series.

Let out and string out are semantically related in extend topic. You can use "Let out" instead a verb "String out", if it concerns topics such as lengthen, longer.