Hope Bagenal, an Acoustics scientist, divided Auditoriums
into two main groups: those with cavern-like acoustics and
those with open air acoustics. Out of the first group concert
halls are born, and from the second one, opera houses. The
acoustics of the concert hall, with its long reverberation,
merges the sounds coming from different sound sources. On
the contrary, the theatre acoustics separate them.
In the concert halls, the "fusion" tends to merge
the sounds produced by the different instruments in the
orchestra, making it so that this is perceived by the listeners
as one single sound source. In opera houses, with the open
air acoustics, the "separation" which is a consequence
of an extremely brief duration of the reverberation time,
makes it so that only the language (spoken, sung) is clear
The traditional configuration of the Italian opera house,
the traditional "singing voice" opera house, generally
works well with the orchestra in the pit (under the audience).
In fact, the sound quality worsens only when the orchestra
rises to the stage, above the audience. For this reason,
the space assigned to the performance and listening to concerts
is the "concert hall", the Auditorium.
Nonetheless, a concert can also be performed and listened
to in a church, a garden, a theatre, etc. Looking at the
Italian conditions, the widespread presence of "all'Italiana"
opera houses in almost every city makes it so that these
buildings are used for all musical shows and therefore even
for instrumental, symphony or chamber music concerts. But
the performance of a concert in an opera house is however,
an inappropriate act.
The Acoustics of the opera house, as we have already mentioned,
are generally suited neither to the performance nor the
listening of an instrumental music concert.
The theatre, however, can adequately host a concert if
it is equipped with an electro-acoustic system of artificial
reverberation (not an amplification system) or, better yet,
an Acoustic Shell for Orchestras.