Before 1876 when Emile Berliner invented the first microphone used as a telephone voice transmitter, it would not have been possible to hear the prayers that were said by the priest at the High Altar of a large Church unless he shouted (a suggestion made by Luther) or sang. Hence, at High Mass in the traditional form, any prayers that are not sung are said secreto. To preach, the priest would walk some way down the nave, climb into a pulpit, and project his voice with the aid of a sounding board above him.
Now we have clip-on radio microphones that can transmit every whisper, cough and snuffle of the celebrant, catching sometimes on the polyester collar of modern vestments to interject loud scratching noises into the Mass. Fortunately I think that the use of these devices is now being called into question. In the older form of the Mass, microphones are not generally used except for preaching, where they will usually be necessary until the pulpit is rediscovered.
The bad influence of the microphone is seen most obviously in religious communities where they are used in the singing of the office for parts that are sung solo by one member of the choir at a lectern - or worse, as a means of amplifying the schola. I remember the great László Dobszay complaining about this, saying that he wanted to hear the schola, not a loudspeaker.
To a member of the congregation, the prayers, the dialogue, the readings, the sermon, and the parish announcements are all emanations from one and the same source, the nearest loudspeaker. In my pew, I see the priest look towards me, but I hear his voice coming from another direction, that of the loudspeaker.The article also suggests other ways in which the microphone has affected the Liturgy in recent times.
Dropping the use of the microphone is something that will seem madness to many who are used to the hearing-every-word aspect of the modern liturgy. Therefore it is worth remembering that the audibility of every word cannot be of the essence of the Christian liturgy since Christians managed without microphones for more than 90% of the Church's life to date.
H/T The Chant Café