# Archaeoacoustics around the World: A Literature Review (2016-2022)
## 4 Discussion
### Recent Advances  
#### 4.1.1 Measurement and Characterization  
The research objective of these studies was to measure the acoustics of a particular place and evaluate the key parameters that affect sound propagation. Acoustic characterization is fundamental to comprehend the sound propagation behavior of a place.  
In general, researchers of pre-Hispanic zones attempted to understand if inhabitants in those places considered acoustics when constructing their buildings. Authors proposed that these places could have been used for rituals, mass events, and religious events.  
Some other authors sought to characterize more recent places to investigate the acoustic behavior of those sites and how they have changed over time. An example of this investigation is the work conducted in the Acheiropoietos Basilica and the Cathedral of Hagia Sophia in Greece, where authors aimed to explore the choral songs related to the acoustic conditions of the place [34]. Other examples are the research undertaken by [PERSON] [35] and [PERSON] [36], who acoustically characterized the Paphos Theater in Cyprus, and the theater of Tymafaris in Italy, respectively. They studied the acoustic characteristics of ancient open-air theaters and the use given to these places. [PERSON] investigated the acoustics of two Roman theaters in the Cartigiensis province of Hispania, Spain [20]. In [38], the authors performed the characterization of the Roman theatre in Spain, which has the best-preserved cavea in Hispania and the amphitheater with its southern restored cavea. Study [39] developed the measurements at eight mosques in Turkey. Additionally, there is the case of an investigation in Mexico, where the acoustic characterization of the Cathedral of Mexico City was carried out [37]. Finally, an interesting work to point out is that conducted by [PERSON], who used a scale model of the Stonehenge ruins to obtain configurations as those presented in ancient times. In this case, the stones could be relocated to analyze different acoustic scenarios [23].  
In terms of measurement quality, it is essential to emphasize that several works [20; 23; 34; 35; 36; 38; 39; 40; 41; 42; 43; 44; 45; 46] were conducted in accordance with the ISO 3382-1:2009 standard, ensuring that results could be reproduced or compared eventually. Moreover, almost all the studies that characterized spaces used loudspeakers as a sound source, with the exception of [37] that used a gun and [24; 46] that used balloons. [PERSON] also used a second sound source: a firecracker blast [36]. Most of these studies employed measurement microphones, with the exception of [26]. Some studies also utilized portable recorders. Most of the authors calculated acoustic parameters related to the reverberation time, such as T\({}_{20}\), T\({}_{30}\), EDT, and T\({}_{60}\). In [33; 36; 37; 38; 39; 42; 46], parameters C\({}_{50}\), C\({}_{80}\), D\({}_{50}\), and ALcons were included. Additionally, the authors in [26] reported the power spectrum and level attenuation using different sound sources, and [24] obtained the normal modes of their studied site. Regarding the reverberation time, Table 2 presents information on the values obtained in various investigations. It can be observed that these values vary greatly, which is understandable as the studies were conducted in different places such as cathedrals, open and closedaters, churches, etc. This results in values ranging from as low as 0.5 s to as high as 15 s.