Chavin

Chavín de Huántar Archaeological Acoustics Project

Acoustic Measurement, Archiving, Analysis and Modeling, and Simulation/Installation

Chavín de Huántar is a monumental World Heritage archaeological site in the Peruvian highlands predating Inca society by over 2000 years. The importance of site acoustics is suggested by distinctive architectural features, notably an extensive network of underground galleries used in part for ritual purposes. The labyrinthine galleries are arranged in a series of small rectangular alcoves off narrow corridors.

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. Preliminary acoustic measurements at Chavín show a short reverberation time, dense and energetic early reflections, and a large lateral energy fraction. The short reverberation time would enable rhythmically articulated group performance using Strombus shell trumpets found onsite. The early reflections would provide strong acoustic reinforcement and consistent resonances for participants in gallery alcoves. The wide soundfield would envelop participants, contributing to the ritual experience. Thus, measurement and modeling may be used to understand the implications of auditory experiences within the galleries as related to the site’s role in developing religious authority.

Team Information

Co-investigators:

• John Rick, PhD, Professor, Stanford University, Archaeology/Anthropology
• Julius O. Smith, PhD, Professor, Stanford University, Center for Computer Research in Music and Acoustics (CCRMA)/Electrical Engineering (by courtesy)
• Jonathan S. Abel, PhD, Consulting Professor, Stanford University, CCRMA
• Patty Huang, MA, Graduate Student, Stanford University, CCRMA
• Miriam Kolar, MFA, Graduate Student, Stanford University, CCRMA

Coordinator:

• John Chowning, DMA, Professor Emeritus, Stanford University, CCRMA/Music

Local collaborators:

• (Museum director)

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 on-site measurements

Preparation

• Preliminary on-site tests [completed 12/07]
• Preliminary on-site tests [to be completed 3/08]
• Specification of test and recording equipment [ongoing; 1-2/08]
• Purchase and assemble gear [ongoing; 2-?/08]

Simulation Trials in local environments

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

Specify provisional mapping for sound source-receiver placements from CAD rendering [in progress 1/08]

• from each chamber to main space
• least damaged areas
• with and without plastering
• peculiar geometries (e.g. , adjoining (comb-like) chambers, etc)

On site measurements at Chavín

• Plastering of section of Chavín (selection of plastered sections is critical (soon after arrival to allow for drying)
• Adjust mapping of source-receiver points

Measurements -- sources

• balloon pops
• speaker-generated sinusoidal chirps
• other signals
• strombus trumpet live/recorded
• record stream/water sound, wind noise

Measurements -- receivers

• distributed mics
• in-ear-canal mics

Costs

• $3000 (2/08) equipment
• $13000 (summer 2008) equipment, data collection costs, logistical support [TBD]
• $8000 travel and accommodations (2 weeks on site) for 2 faculty (Rick, Abel), 2 graduate students (Huang, Kolar)
• $1000 on site wall-building, plastering, and removal (summer 2008)

Potential Sources of Funding

• National Geographic [1]
• Stanford Institute for Creativity in the Arts (SICA) [2]

Phase 2. Analysis and Generation of 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).

Costs

Funding Sources

• National Geographic [3]
• National Endowment for the Humanities- Collaborative Research Grants [4]
• National Science Foundation- Archaeology and Archaeometry [5]

Phase 3. Electroacoustic simulation & Public interface

Locations

• Stanford
• Chavín Museum
• Quantify and compensate for support structures
• Simulation of plastered walls
• National Museum Peru

Equipment

Public interface

• 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.)