Background & Summary

This dataset refers to the acoustic measurements of the archaeological zone of Edzna in Campeche, Mexico, which were recorded for site characterization purposes. A previous review of the literature1 identified twenty-eight studies related to acoustic measurements from various locations around the world between 2016–2022. Twenty of them were conducted in Europe2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21, four of them in Asia22,23,24,25, three of them in America26,27,28, and the remaining one in Africa29. This indicates that only three of the studies were conducted in the Americas, and none of them focused on the Mayan culture, despite its significant role in the development of the inhabitants in America. Therefore, this study was undertaken to address this research gap, and provide insight into the acoustic characteristics of the Edzna site. Additionally, it should be noted that there are no previous databases with these characteristics.

Edzna is an archaeological site belonging to the ancient Mayan civilization, located in the southeastern region of Yucatan Peninsula in the state of Campeche, Mexico. The site is situated approximately 55 kilometers southeast of the city of “San Francisco de Campeche”. Edzna was first discovered in the early 1900s, and since then, it has been an important site for archaeological research and exploration30. Its impressive structures, including the Great Acropolis, Nohochna and the Ballcourt, are testament to the rich history and culture of the Mayan people. Some of the main places around the archaeological zone are: (1) Main Plaza, (2) Nohochna, (3) Great Acropolis, (4) The Five-Story building, (5) Small Acropolis. See Fig. 1.

Fig. 1
figure 1

Edzna map and the main places around it. These are: (1) the main plaza, likely used for ceremonies; (2) Nohochna, which probably served as bleachers for seating; (3) the Great Acropolis, the most important and private area of the complex; (4) the Five-Story Building, the most significant pyramid in the entire complex; and (5) the Small Acropolis, a place for resting.

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Mexico, a country blessed with a wealth of cultural and historical heritage, boasts an abundance of archaeological sites. Archaeoacoustics-based research has allowed to identify the favored spots for performing ceremonial music in Palenque31, and explore the intriguing sound effects within the structures of Chichen Itza32,33. Moreover, researchers have discovered remarkable speech intelligibility at Cañada de la Virgen34.

Edzna, is a former site of the Mayan culture. The acoustic properties of this architectural complex embody intangible heritage, encompassing a collection of customs, knowledge, traditions, and living expressions transmitted through oral traditions, rituals, festive events, and practices associated with nature and the universe. This exploration grants profound insights into Mayan society, enabling a deeper understanding of the religious ceremonies held, the intricacies of political governance35.

The Great Acropolis had several constructions, where various ritual activities took place, such as the Temazcal and the platform located at the center of the courtyard, in addition to the Five-story building. The Nohochna could have had astronomical functions and, at the same time, seemed suitable for conducting various gatherings, such as political or military councils, religious or educational activities, various ceremonies like dances, banquets, or processions, as well as activities related to record-keeping, storage, and distribution of materials or objects30. Regarding the archaeological materials that might provide evidence of musical or sound activities in Edzná, there are some indications that can be found in the iconography of the stelae and other iconographic and epigraphic materials from Edzna. For example, stela 13 seems to depict a drum, and stela 18 shows a governor dancing36.

To carry out the acoustic characterization of Edzna, the equipment to be used had to be calibrated beforehand. This was done prior to visiting the site. Once at the archaeological zone, it was necessary to determine the locations for both: the sound source and, the microphones. Background noise measurements of the site were then taken, following the guidelines specified in the ISO 3382-1:2009 standard37. Then the acoustic measurements of the place were performed using two types of signals: (1) Maximum Length Sequence (MLS) and (2) Logarithmic Sine Sweep (LSS) generated by a sound source Behringer DR115DSP. Two different sound capture systems were used for the recordings: (1) a Shure MX 150 microphone, and (2) a binaural head Neumann KU 100. These systems were used to ensure that accurate and reliable measurements were obtained for the acoustic characterization of the site. The Fig. 2 presents the schematic overview of the measurements.

Fig. 2
figure 2

Schematic overview of the measurements carried out. As an example, the emission point PE3 and the recording point PR20 located in the Great Acropolis area are herein depicted. The building in the background corresponds to the Five-Story building.

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The data herein presented allow to obtain various acoustic parameters of the archaeological zone at different measurement points. This includes parameters such as Early Decay Time (EDT), Reverberation Time (RT60), voice Clarity (C50), instrument Clarity (C80), or Definition (D50), which are essential for achieving a comprehensive acoustic characterization of the site.

Additionally, the data collected can be used to auralize different types of sounds, such as musical instruments or sound effects. To have an aural experience where sounds could be listened to as they are perceived in the archaeological zone, without the need of physical present, sound achievable. Such auralizations could help to enhance the experience of the site and provide a better understanding of the acoustic properties of the ancient structures. Moreover, this database can be utilized for machine learning purposes to predict or classify several situations related to the archaeological zone, such as acoustic environment classification, acoustic anomaly detection, human activity recognition, among others.

Methods

For this study, the materials and equipment used to collect measurements included an HP ProBook 640 G2 laptop, a Behringer UMC 404 HD audio interface, and a Behringer DR115DSP speaker. The microphone employed was the Shure MX 150 B/O, which was equipped with its windscreen. Additionally, a Neumann KU 100 binaural head, a Bruel & Kjaer type 2270 sound level meter with a microphone head 4189 and a preamplifier ZC 0032, along with a Bruel & Kjaer 4231 acoustic calibrator were utilized.

Furthermore, to ensure a continuous power supply, a Baldr Pioneer 330 portable power station was used. Environmental temperature measurements were taken using a Steren TER-100 environmental thermometer and a 50-meter metric measuring wheel. Additionally, Matlab was employed to develop these measurements.

The experimental procedure is illustrated in Fig. 3. This one was undertaken as follows. First, background noise measurements were taken, and it was identified that the background noise in the area was 35 dBA, which remained constant throughout the archaeological place. Then, system levels were adjusted, i.e., the speaker output level was checked, and the microphone level was verified to guarantee it was receiving enough level without reaching saturation. A SPL of 115 dB at 1 m was measured to provide enough level for subsequent acoustic measurements.

Fig. 3
figure 3

Experimental procedure to record the acoustic measurements of the archaeological site, Edzna (Campeche, Mexico).

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Having adjusted the levels, the microphones were positioned. A total of three were used, two in the binaural head and one located over the head. The binaural head microphones (located inside the ears) were placed at a height of 1.6 m, and the other microphone was placed 40 cm above the head at a height of 2 m. In none case, the microphones were placed less than 1 m from any reflective surfaces (e.g., walls) to comply with ISO 3382-1:2009 standard37. Once the microphones were positioned, the speaker was placed at a height of 1.6 m from the center of the larger driver. See Fig. 4. To properly capture all the information of the reflections in the location, the speaker was placed in two positions at each measurement point: 1) at 0° and 2) at 180° from the initial configuration.

Fig. 4
figure 4

Electroacoustic system configuration. Five items are identified: (1) laptop; (2) audio interface; (3) speaker; (4) microphone; (5) binaural head.

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Once both the microphones and the speaker were in place, measurements were taken by generating a MLS signal and recording the signals. Subsequently, a LSS was generated, and the recordings were repeated. The average weather conditions during the measurements were the following: relative humidity 76%, wind speed 11.5 km/h, and temperature 34 °C. Finally, this procedure was repeated 32 times, one for each measurement point. The measurement points are depicted in Fig. 5.

Fig. 5
figure 5

Acoustic measurement points in Edzna. In total, 32 reception and 4 emission points were used.

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It is important to note that these measurements were taken in an area with no access to electrical power. Consequently, a Portable Power Station was requited, what limited the measurement options.

Data Records

The data has been organized maintaining the structure presented in Fig. 6.

Fig. 6
figure 6

Data organization. The information was organized into four levels: the first one is the root, that contains all the information; the second one organizes the four sound emission points, the third one groups the two types of signals, and finally, the fourth one separates the information by microphone type, among the three options.

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The database is available at https://data.mendeley.com/datasets/2vy7f87cdx/138.

Technical Validation

To carry out the technical validation of the acoustic measurements, a previous calibration process of the electroacoustic chain used during the measurements was necessary. This calibration prevented that the individual responses of the connected equipment could have affected the acoustic measurements. In addition, the inverse filtering method39 was used to adjust the levels and generate a response system as flat as possible. This procedure guaranteed that any acoustic change recorded during the measurements had corresponded exclusively to the response of the system being evaluated, in this case, the archaeological zone of Edzna. The calibration was carried out using a program developed in Matlab, and the implementation code can be consulted in Ibarra et al.39. The Fig. 7 shows the original system spectrum, the calibrated spectrum, and the PR2 spectrum obtained from the measurement of the point PR2 in the archaeological zone, as a case in point.

Fig. 7
figure 7

Original, calibrated and PR2 spectrums. The blue line represents the original system spectrum recorded by the electroacoustic system, the orange corresponds to the calibrated spectrum, and the green signal represents the PR2 spectrum, obtained of the measurement at the archaeological site.

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Usage Notes

To read and analyze this data, it is recommended to use Matlab software. Additionally, acoustic parameters can be obtained from this data using the Aurora tool for Audacity, which has been used in previous works6,8,17,21,22.