# Archaeoacoustics around the World: A Literature Review (2016-2022)
###### Abstract
The ALcons formula is: \[\text{ALcons}\ \approx 0.652\ \left(\frac{\text{r}_{\text{LH}}}{\text{r}_{ \text{H}}}\right)^{2}\text{T}_{60}\ \%\] (4) where: \(\text{r}_{\text{LH}}\): distance sound source-listener; \(\text{r}_{\text{H}}\): reverberation radius or, critical distance \(\text{r}_{\text{R}}\), in case of directional sound sources. Speech transmission index (STI)--A parameter between 0 and 1 that indicates the speech transmission quality [11]. The STI formula is: \[\mathrm{STI}=\frac{\left(\overline{S/N}\right)_{\mathrm{ap}}+15}{30}\] (5) where: \(\left(\overline{S/N}\right)_{\mathrm{ap}}\): total apparent noise/signal. 7. Clarity50 (C50) measures the clarity or intelligibility of speech. It is expressed in decibels. It is related to the sound energy that arrives at a listener within 50 milliseconds [11]. The C50 formula is: \[\mathrm{C}_{50}=10\log\frac{\int_{0}^{0.05}\mathrm{P}^{2}(t)\mathrm{dt}}{ \int_{0.05}^{\infty}\mathrm{P}^{2}(t)\mathrm{dt}}\] (6) where: P(t): instantaneous sound pressure in Pascals. 8. Definition (D50) is similar to C50 but is expressed in percentage [12]. The D50 formula is: \[\mathrm{D}_{50}=\frac{\int_{0}^{0.05}\mathrm{P}^{2}(t)\mathrm{dt}}{\int_{0}^{ \infty}\mathrm{P}^{2}(t)\mathrm{dt}}\] (7) where: P(t): instantaneous sound pressure in Pascals. 9. Clarity80 (C80) measures the clarity or intelligibility of music. It is expressed in dB. It is related to the sound energy that arrives at a listener within 80 milliseconds [11]. The C80 formula is: \[\mathrm{C}_{80}=10\log\frac{\int_{0}^{0.08}\mathrm{P}^{2}(t)\mathrm{dt}}{\int_ {0.08}^{\infty}\mathrm{P}^{2}(t)\mathrm{dt}}\] (8) where: P(t): instantaneous sound pressure in Pascals. In addition to all these acoustic parameters, the most common method used to reproduce audio spatially has been Ambisonics. This method refers to the representation of directional auditory data by using spatial sampling that is then resynthesized through a finite number of point sources [13]. Despite being extensively studied from an architectural standpoint, the acoustic characterization of many archaeological sites has not been thoroughly examined. Learning more about acoustics and sounds in archaeological sites could provide valuable insights into the cultures and customs of ancient inhabitants. This knowledge not only serves as cultural heritage for humanity, but it is also a way to bring closer the thoughts and worldview of the people who lived in those sites. However, despite the numerous archaeological sites found worldwide (e.g., Teotihuacan in Mexico, Easter Island in Chile, The Ta Prohm in Cambodia, The Luxor temple in Egypt, Longmen Grottoes in China, and Machu Picchu in Peru), the study of Archaeoustics is limited or even nonexistent. Therefore, it is important to consider the most recent scientific advances in this field to identify current research gaps and unanswered questions. Therefore, the main goal of this paper is to review papers published between 2016 and 2022 in the field of Archaeoacoustics. This review aims to identify recent advances in this field, including (1) the applied technologies to characterize, simulate, or recreate ancient places, (2) the methodologies followed to do so (Section 2), (3) the most relevant findings related to Archaeoacoustics worldwide (Section 3), and (4) a critical opinion about advances towards Archaeoacoustics characterization of worldwide sites (Sections 4 and 5).