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Preface

The word Acoustics is originated from the Greek word akouein (ἀκούειν), and Joseph Sauveur coined the term acoustics for this science of sound he pioneered in 1701 [1].

Introduction

Archaeoacoustics, also known as Auditory Archaeology, is an emerging interdisciplinary field that combines archaeology and acoustics. It focuses on studying archaeological spaces by examining their acoustic properties and characteristics. [2][3][4]

According to Navas-Reascos et al., Archaeoacoustics has had a wide variety of study aims, including socio-political studies to obtain information among different cultures.

Acoustical analysis procedures of Archaeoacoustics

The acoustical analysis procedures of Archaeoacoustics researches have been standardized to ensure similar quality characterizations of archaeological spaces [5][6].

Reverberation time $T_{60}$

Reverberation time $T_{60}$ is regarded as the most basic and important objective parameter of the Acoustics study, which can be used to measure how long a sound remains after the sound source is turned off. It was first proposed by W. C. Sabine (1868-1919), and it marked the beginning of modern room acoustics. It is measured in seconds and is obtained when the sound energy reduces by 60 $\text{dB}$. Sabine’s formula is:

where $V$ represents the analyzed room volume (in cubic meters), and $A$ denotes the equivalent absorption surface of the room (in square meters).

Sound pressure level (SPL)

The sound pressure level (SPL) or acoustic pressure level (APL) quantifies the magnitude of a sound field and is expressed in decibels ($\text{dB}$)::

where $P$ denotes the SI unit of root mean square sound pressure mesured in Pascal (Pa), $P_0$ represents the reference sound pressure in air, set at a value of 20 $\mu$Pa ¹. SPL can be measured using a microphone in air and with a hydrophone in water.

1 Pa = an SPL of

Early decay time (EDT)

Early decay time (EDT) is derived from the reverberation time decay $T$, measures the rate of the decay. The difference is the EDT value is evaluated from the initial part, namly the interval between 0 and −10 $\text{dB}$. EDT can be defined by two ways:

or

It is considered as a better descriptor of reverberance than $T_{60}$ [7].

Sound strength $G$

Sound strength ($G$) relates closely to loudness and represents the difference in sound pressure level (SPL) between an omnidirectional sound source at a specific point in a room and the SPL produced by the same source in an open field, measured at a distance of 10 meters.

This measurement is crucial as it reflects the influence of the space on perceived loudness. Specifically, it quantifies the difference in $\text{dB}$ between the level of a continuous, calibrated sound source measured in the space and the level generated by the same source in anechoic surroundings at 10 meters. [7] The formula for calculating the sound strength $G$ is as follows:

Articulation loss of consonants (ALcons)

Speech transmission index (STI)

Clarity

Clarity50 (C50)

Definition (D50)

Clarity80 (C80)

References

[1] R.B. Lindsay, Acoustics: Historical and Philosophical Development, Dowden, Hutchinson & Ross, Stroudsburg, PA 1973, p. 88, Translation of Sauveur’s paper. https://archive.org/details/isbn_0879330155

[2] Valenzuela, J.; Díaz-Andreu, M.; Escera, C. Psychology Meets Archaeology: Psychoarchaeoacoustics for Understanding Ancient Minds and Their Relationship to the Sacred. Front. Psychol. 2020, 11, 550794.

[3] Debertolis, P.; Bisconti, N. Archaeoacoustics in Ancient Sites. A New Way to Analyzing Archaeological Locations. In Proceedings of the 1st International Virtual Conference on Advanced Scientific Results SCIECONF 2013, Žilina, Slovakia, 10–11 June 2013; pp. 10–14.

[4] Aletta, F.; Kang, J. Historical Acoustics: Relationships between People and Sound over Time. Acoustics 2020, 2, 128–130.

[5] Ramos Amézquita, A. Metodologia de Analisis Acustico de Sitios Arqueologicos de Mesoamerica; Universidad Politécnica de Madrid: Madrid, Spain, 2015.

[6] Ramos-Amezquita, A.; Ibarra-Zarate, D.I. Acoustic characterization of three archeological sites in the state of Guanajuato, Mexico. Proc. Meet. Acoust. Acoust. Soc. Am. 2013, 19, 040100.

[7] M. Schroeder, Thomas D. Rossing, F. Dunn, W. M. Hartmann, D. M. Campbell, and N. H. Fletcher. 2007. Springer Handbook of Acoustics (1st. ed.). Springer Publishing Company, Incorporated.