The use of microphones can be sensible in certain situations, to some extent even necessary.
In smaller, enclosed spaces (lofts) their use in general is not necessary.
Especially in scenes with vocals and instrumental accompaniment, the use of corded microphones can help to improve clarity. Since it's more about singing and less about acting, corded microphones are not a big hindrance when performing, or rather, when singing.
If already at hand, then...
If, however, corded microphones are already in place, they can be used throughout (additionally) for certain plays and play ideas. If they are away from the main focus (for example on a stand at the edge), you can intensify certain sounds in the play (for example rolling thunder), also some plays like small voices are more impactful.
For performances in large halls or outdoors, microphones must be used as a rule. Spoken words get lost in the distance. The problem is that corded microphones - except when singing - are not practical, because they limit and hinder acting too much. Finally, you have to hold the microphone with one hand and then also in front of you mouth. One also needs -- non-corded -- radio-microphones (headsets). If these are not provided by the organizer, it will get expensive. One has -- for each actor! -- either to rent or buy them. - Rent or buy. That can easily cost many hundred dollars.
Headsets/ Neckband Microphones
Modern microphone setups are attached to the external ear or to the neck (so called neckband microphones) and are barely visible to the audience. Also the microphones themselves are tiny. Each microphone requires a transmitter, that must be attached to the body in an inconspicuous place. In addition a receiver is required. It is important that signal broadcasting is uninterrupted, because repeated losses of sound are unnerving and irritating for the actors and the audience. When purchasing several instruments of acceptable quality - lets say at least three - the price will fall into the four digit range. Therefore, headsets are only affordable for (semi-) professional groups or wealthy people.
It goes without saying that the test before each performance is to ensure that all microphones are working and of course that radio-microphones/headsets are able to broadcast without interference. "Beloved" are interruptions caused by loose connections. Therefore it makes sense to move the cables back and forth while performing the sound check.
by Guido Boyke