Open-air theatres
J.H. Rindel 2025
This is a short introduction to open-air theatres and their acoustical characteristics. In modern English, the word amphitheatre is often used for any structure with a sloping seating. However, here we distinguish between amphitheatres as a specific Roman building type and other theatres.
Ancient Greek theatres
Theatres developed about two and a half thousand years ago in ancient Greece. Their purpose was Satyr plays with dance and music, tragedies, and comedies. For the drama performances the acoustics had to support the speech intelligibility, i.e. sufficient high sound level and good clarity.
The good acoustics was mainly due to sound reflections from the place between the audience and the scene building (the orchestra) and from scene building itself. Unfortunately, the scene building is not preserved in the remains of the ancient Greek theatres.
The early Greek theatres had linear seat rows (Figure 1), but during the fourth century BCE (Before Common Era) the canonical theatre type was developed. It is characterised by semicircular seating area (koilon) with steeply sloping seat rows and a circular orchestra (Figure 2). The seating area could also exceed a 180 degrees semicircle. The theatres were built in places with a natural sloping ground.
In the Hellenistic period (after c 320 BCE) the size of the theatres increased and the seating capacity could be 10 000 or more (Figure 3).
Figure 1. Early Greek theatre with linear seat rows (Thorikos). Photo: P.O. Rindel.
Figure 2. Greek theatre with semicircular koilon (Oeniades). Photo by the author.
Figure 3. Hellenistic theatre (Epidaurus). Photo by the author.
Ancient Roman theatres
Roman theatres developed during the first century BCE. In Rome, the first permanent stone theatre was built by Pompejus and opened 55 BCE. The Roman theatres were usually built in a city centre and not necessarily in a naturally sloping setting as the Greek theatres. The seating area (cavea) was semicircular and with a steep slope, but the orchestra was smaller than in the Greek theatres and reduced to a half circle. The scene building was increased to be several stories high and could have a canopy sound reflector above the scene. Surrounding the audience was a colonnade connected to the scene building (Figure 4).
Acoustically, the sound was supported by reflections from the scene building, from the canopy (if any) and from the colonnade. Thus, the audience would receive sound reflections from the front, from above, from the sides, and from behind. Although an open-air theatre, the horizontal sound reflections could create a kind of reverberance. Some of the best-preserved Roman theatres are used today for concerts (Figure 5).
Figure 4. The Aspendos theatre. The photo shows a modern extended scene built into the orchestra area. Photo by the author.
Figure 5. Modern use of a Roman theatre for a concert (Aspendos). Photo by the author.
Ancient Roman Amphitheatres
The Roman amphitheatres represent a very different kind of theatre. They were created for the purpose of gladiator fights and combats with wild animals. Such performances can be traced back to ancient Etruscan or Campanian traditions. One of the first permanent amphitheatre was built around 75 BCE in Pompeii (Figure 6). While the Roman theatres were built in the city centre, the amphitheatres were placed in the outskirts of the city, sometimes outside the city walls.
The amphitheatre is characterised by the seating on all sides around an arena, which is normally of elliptical shape. The design features good sight lines whereas acoustics are unimportant, and there are no particular structures supporting the sound.
Originally, this kind of theatre was called spectacula, meaning a place for watching. The name amphitheatre came later. During the first and second century the size of the amphitheatres increased, and on the top was added a colonnade like the one in a typical Roman theatre. The biggest amphitheatre ever built is the Colosseum in Rome, inaugurated in 80 CE (Common Era). Today, ancient Roman amphitheatres are often used for bull fighting (in Spain and France) or they are used for concerts and opera performances as in Verona (Figure 7).
Figure 7. Roman amphitheatre built in Verona 30 CE. For modern opera performance the arena is divided into a seating area (left) and a stage (right). Photo: Arne Müseler / www.arne-mueseler.com, CC BY-SA 3.0 de
Courtyard theatres
In England, old style coaching inns had a galleried courtyard, and this was sometimes used for performances by a theatre company. This kind of theatre performance developed to a specific type of open-air theatre, the courtyard theatre. The most famous example is the Globe theatre in London (Figure 8). This was originally built 1599 specifically for Shakespeare’s theatre plays.
Like in the Roman theatres, the courtyard theatres often have a canopy reflector above the stage. The floor is not sloping and is used for a standing audience. Seated spectators are placed in the galleries.
Figure 8. The Globe theatre in London. Shakespeare’s playhouse, originally built 1599. Photo: Britannica
Another kind of courtyard theatre is when the courtyard in an ancient castle is applied for concerts and opera performances. An example is the Oscarsborg fortress, Norway, in which the courtyard is used for opera performances in the summer (Figure 9). Acoustically, such spaces can provide some reverberance due the horizontal reflections from the surrounding walls. The lack of a ceiling means that there is no risk of too long reverberation time.
Figure 9. Oscarsborg fortress, Norway. Photo: Andreas Hanssen Vang.
Modern open-air theatres
Places with a natural sloping ground are sometimes converted into open-air theatres by building a stage and a stage house that reflects the sound towards the audience. An example of this is the Tallinn Song Festival Grounds in Estonia (Figure 10). The stage holds up to 15 000 singers. The number of people in the audience may reach 100 000.
Figure 10. Tallinn Song Festival Grounds. Photo: Dennis G. Jarvis, CC BY-SA 2.0, via Wikimedia Commons.
References for further reading
Bomgardner, D. (2021). The story of the Roman amphitheatre. Second Edition. Routledge, Oxon, New York. ISBN: 9780367625115.
Girón, S., Álvarez-Corbacho, Á. & Zamarreño, T. (2020). Exploring the Acoustics of Ancient Open-Air Theaters. Archives of Acoustics, 45, 181-208. DOI: 10.24425/aoa.2020.132494.
Rindel, J.H. (2013). Roman Theatres and Revival of Their Acoustics in the ERATO Project. Acta Acustica/Acustica, 99, pp. 21-29. DOI: 10.3813/AAA.918584.
Rindel, J.H. (2023). A note on meaningful acoustical parameters for open-air theatres. Acta Acustica, 7, 20. DOI: 10.1051/aacus/2023015.
Rindel, J.H. (2025a). Acoustical aspects of the development of Greek theaters in the 4th century B.C.E. J. Acoust. Soc. Am., 157 (3), 2042-2066. DOI: 10.1121/10.0036255.
Rindel, J.H. (2025b). The acoustics of open-air theatres: Why traditional parameters don’t apply. Scientia, April 2025. DOI: doi.org/10.33548/SCIENTIA1276.
Sear, F. (2006). Roman Theaters. An Architectural Study. Oxford monographs on classical archaeology. University Press, Oxford. ISBN: 978-0-19-814469-4.
Welch, K.E. (2007). The Roman amphitheater: from its origin to the Colosseum. Cambridge University Press. ISBN: 9780521744355.
