Revision as of 20:21, 26 July 2008

Chavín de Huántar Archaeological Acoustics Project

Acoustic Measurement, Archiving, Analysis, Modeling, and Simulation/Installation – A collaboration between Stanford University's Center for Computer Research in Music and Acoustics (CCRMA) and Archaeology/Anthropology

Chavín de Huántar is a monumental World Heritage archaeological site [1] in the Peruvian highlands predating Inca society by over 2000 years. Since 1995 Professor John Rick of Stanford University and teams have been excavating the site [2], revealing peculiar and unique architectural features in both surface and underground structures. It is the underground structures, a complex of labyrinthine galleries, corridors, shafts and drains, built of cut stone block, that are of particular interest to this project, because explanations for their purpose and function have led to Rick’s hypothesis that they were constructed, at enormous cost in labor, to establish social hierarchy through sensory manipulation in the context of religious ritual: a priest-elite over the novitiates. Most of these underground galleries are original; walls, ceiling, and floor are still present and complete -- an unusually intact condition for ancient architecture.

In 2001, twenty intact engraved, identically prepared Strombus (conch) shell trumpets were discovered by Rick in a gallery at Chavín, reinforcing his hypothesis that the acoustic properties of the site were fundamental to ancient ritual and perhaps even a determinant in architectural layout and design. What are the sonic characteristics of these trumpets and architectural structures? What can be determined regarding the relationship between the Strombus trumpets and the acoustic features of the site? Is there evidence of intentional acoustic design in Chavín architecture, and what would it imply for ancient cultural abilities and political strategies? Acoustic measurements, analysis, and models will help answer such questions, providing Rick with data to elaborate and refine his hypothesis regarding the importance of sensory manipulation in Chavín ritual.

Since an important area of research at CCRMA is computational physical modeling of acoustic sources and reverberant spaces, we saw the opportunity to join two disciplines with the purpose of extending Rick’s team’s mappings and CAD renderings of Chavín to include computer simulation of site acoustics, using recorded excitation sources such as Strombus trumpets, rushing water through canals, and human voice. Acoustic measurements and models of a site can be used to archive site acoustics, estimate the acoustics of inaccessible or alternative site architectures, and reconstruct original site acoustics; they may also be used to corroborate aspects of rituals suggested by other archaeological data. Measurement and modeling may be used to understand the implications of auditory experiences within these galleries as related to the role of the site in developing religious authority.

The site's intact enclosures, primarily without post-period modification, allow for acoustic measurements that reflect original conditions. Such an opportunity to research and archive unmodified ancient architectural structures is rare and timely: Chavín de Huántar is an important tourist attraction, and upcoming required site conservation work will inevitably cause irreversible alteration of its acoustics. It is therefore imperative that onsite measurements be made soon, precisely, and thoroughly. Given adequate funding, our team will be able to do this field work beginning in summer 2008.

Schedule/Planning

Our project is divided into three phases as noted in the timeline below.

Phase 1, in progress since autumn 2007, has involved planning, data collection, analysis, and work on an invited paper to be presented at Acoustics08 in Paris this July; Phase 1 will culminate with field work in Peru to generate a comprehensive acoustic analysis of the site, its materials (to include collaboration with an Earth Sciences specialist) and musical instruments. The academic and creative work of Phases 2 and 3 will not be possible without this data collection. The models developed in Phase 2 will provide a rich research base with which to simulate and evaluate a variety of acoustic conditions, architectural geometries, source placements and listening positions. In order to provide a public interface during Phases 1 and 2, a website chronicling the developing work and ideas using sounds and images will be constructed and maintained. Phase 3 will be a site-independent simulation to reconstruct the auditory-visual experience of the original galleries, exhibited at Stanford and potentially also in the Chavín museum in Peru.

Collaboration with relevant specialists will be approached as the project progresses, including expert shell performers, ethnomusicologists, psychoacousticians, and others. We would like to develop and/or consider other opportunities for engaging the academic community with our work in progress. Related creative projects are anticipated and will be encouraged throughout all phases.

Timeline

 Phase 1: Preparation and Onsite Measurements (work in progress since autumn ‘07 through '09) 
 Phase 2: Analysis and Generation of Computational Physical Model  (projected autumn ’08-’09)  
 Phase 3: Electroacoustic Simulation and Public Interface (projected ’09-‘10) 

Team Information

Co-investigators:

• John Rick, Professor, Stanford University, Archaeology Center and Department of Anthropology
• Jonathan S. Abel, Consulting Professor, Stanford University, Center for Computer Research in Music and Acoustics (CCRMA)
• Julius O. Smith, Professor of Music and Associate Professor (by courtesy) Electrical Engineering, Stanford University, CCRMA
• Patty Huang, MA, PhD Candidate, Stanford University, CCRMA
• Miriam Kolar, MFA, PhD Candidate, Stanford University, CCRMA
• Perry Cook, Professor of Computer Science and Music, Princeton University
• Jyri Huopaniemi, Adjunct Professor of Audio Technology and Software at Helsinki University of Technology; Director of the Media Laboratory in Nokia Research Center
• Cobi van Tonder, Stanford University
• Leila Takayama, PhD, Human-Computer Interaction Researcher

Coordinator:

• John Chowning, Professor Emeritus of Music, Stanford University, Founding Director of CCRMA

Local Collaborators:

• Christian Mesia, PhD, Instituto Nacional de Cultura, Lima

Team Background:

• John Rick has been heading excavations and directing research at the Chavín site since 1995
• Digital waveguide techniques were pioneered at CCRMA by Julius O. Smith III
• Julius O. Smith and Jonathan S. Abel have been working together on acoustic array processing and related problems since 1985
• Patty Huang is a PhD student working under Abel on physical modeling and analysis of reverberant spaces
• Miriam Kolar is a PhD student with extensive field experience in recording engineering
• John Chowning is a composer having long standing interest in spatial modeling
• CCRMA has expertise in field measurements, psychoacoustics, digital signal processing, and artificial reverberation

Phase 1. Preparation and Onsite Measurements

Preparation

• preliminary on-site tests [completed 12/07]
• secondary on-site tests [completed 2/08]
• specification of equipment [ongoing]
• purchasing and assembly of gear [2/08 & ongoing]
• data analysis for Acoustics'08 invited paper [completed 6/08]

Simulation Trials in Stanford environments

• CCRMA stairwell, hallways, “Pit”
• SU subsurface spaces; steam tunnels
• outdoor space similar to Chavín Circular Plaza?

Specify Provisional Mapping (for sound source-receiver placements from CAD rendering) [in progress]

• from each chamber to main space
• least damaged areas
• with and without plastering
• varying geometries

Prototyping for Field measurement Trip #1 [in progress]

• configure equipment and procedures
• specify locations
• develop calibration technique
• map testing sequences

Field Measurements at Chavín [Sept.'08, ? '09]

• evaluate actual conditions
• re-evaluate and adjust testing procedure
• other contextual adjustments
• on site data analysis

Measurements -- Sources

• balloon pops (preliminary)
• speaker-generated test sequences
• strombus trumpet live/recorded
• record stream/water sound, wind noise
• live/recorded human voice

Measurements -- Receivers

• custom mic arrays
• in-ear-canal mics (binaural)

Funding

• 2/08 initial equipment grant -- funded by SICA
• SICA grant for September '08 field work

Potential Sources of Funding

• National Geographic

Equipment Loan

• Sennheiser Research Lab

Microphone Donations

• Countryman Associates, Inc.

Microphone Array Design and Fabrication

• D2M, Inc.

Acoustics'08 Paper

• Presentation in Paris, 3 July 2008

Phase 2. Analysis and Generation of Computational Physical Model

Analysis

• compare plastered and unplastered and extrapolate to the entire structure
• IR measurement to render the modeled spaces
• measurement processing to model the pristine state
• Strombus trumpet

Physical Model

• calculate acoustical properties of materials
• rendering from architectural models
• use waveguide mesh processing
• Stanford invention of and current work with waveguide mesh allows effective method to address computation/simulation of acoustical spaces
• process and match/fit measurements then extend to parts of site that aren't necessarily intact or accessible for comprehensive measurements (plastering).

Potential Funding Sources

• IMLS/National Endowment for the Humanities Digital Partnership [3]
• National Endowment for the Humanities Collaborative Research Grant [4]
• National Science Foundation- Archaeology and Archaeometry [5]

Phase 3. Electroacoustic Simulation & Public Interface

Locations

• Stanford
• National Museum of Chavín

Public Interfaces

• Work-in-progress documentation website
• Virtual walkthrough (headphone tour) in present condition
• Virtual walkthrough (headphone tour) in reconstructed condition
• Enhanced reverberation system for visitor experience
• Installations of replica in various formats (online, DVD, museum, show, etc.)

Conservation & Reconstruction

• Quantify and compensate for support structures
• Simulation of plastered walls