Describe time, space and acoustic response
An audio file becomes scientific evidence through its relationships: to an instrument state, a clock, a measurement position, a room and a processing history.
A shared timeline needs an explicit mapping
Audio frames, video frames, MIDI events and animation ticks do not automatically share a clock. VAO 0.5.0 describes explicit timebases and mappings. Rational rates avoid ambiguous decimal approximations; half-open intervals include their start and exclude their end. A region from frame 0 to frame 48,000 at 48,000 frames per second is therefore one second long, without counting an extra endpoint sample.
A linear mapping relates coordinates as target = source × scale + offset. Both coordinate units matter. For a source measured in audio frames and a target measured in seconds, the scale has units of seconds per frame. Clock drift, residual uncertainty and discontinuities require their own treatment. A single offset can align an onset without explaining drift during a long session, and a mapping must not interpolate across an unmodeled dropout.
Illustrative timing calculation · explanatory notation, not a VAO JSON record
source coordinate: audio frame index at 48,000 frames/second
target coordinate: video time in seconds
scale = 1 / 48,000 seconds/frame
offset = 0.125 seconds
frame 96,000 maps to 2.125 seconds
Keep the measured alignment uncertainty and any discontinuities separately.Cuntz · Illustrative scenario#
How do we identify a passage within a recording?
A timebase defines how positions correspond to time. A half-open interval includes its first position and excludes its end, avoiding an extra sample at a shared boundary.
Work through the example 3 STEPS
For a teaching calculation, take a hypothetical 192,000-frame-per-second audio realization, matching the sampling rate described for the Cuntz thesis recording setup. The excerpt below is illustrative, not an identified take.
State the region in frames
The interval [192000, 384000) starts one second into the signal and spans 192,000 frames: exactly one second at the stated rate.
Keep channels distinct
A stereo frame includes a sample from each channel. The same one-second interval does not become two seconds because there are two channels, nor does it become two independent pipe recordings.
Connect timing systems explicitly
If a video or control timeline starts elsewhere, record a mapping between its timebase and the audio frame positions, including offset and any uncertainty or discontinuity.
BASIS FOR THIS EXAMPLE
- Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)
Submitted dissertation, 11 September 2026; §§8.2.2.1 and 8.4.1, printed pp. 264–265 and 275–276. The historical description and digital inventory require a resolved mapping; the manuscript is not redistributed here.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
This numerical example is a teaching calculation, not a new analysis of a published Cuntz audio excerpt.
The useful distinction. An exact excerpt needs the signal realization, channel interpretation, frame interval and rate.
A position means something within a frame
A coordinate triple is incomplete without units, axis definitions, handedness and a reference frame. A microphone pose in an instrument frame differs from its pose in a room frame. A geographic longitude and latitude pair must not be silently interpreted as local Cartesian x and y. Explicit transformations and their provenance let another client reconstruct the intended relations or identify a missing conversion.
For a measured response, preserve the source and receiver positions, orientations where relevant, instrument and room state, and the method used to establish them. An approximate position should remain approximate. Giving more decimal places to an estimated coordinate does not improve the underlying measurement. A change of coordinate frame is a transformation; it is not a new acoustic observation.
Cuntz · Released record#
Can we measure the original organ by rotating its model?
A coordinate frame defines axes, orientation and units. A verified physical scale additionally requires evidence linking those coordinates to the physical object.
Work through the example 3 STEPS
The released model declares a right-handed, Y-up frame with metre units, while its purpose limitation says the source scale has not been verified by a physical survey.
Read the coordinate convention
The convention tells a renderer how to interpret model coordinates and orient the scene. It helps two applications agree about the same geometry.
Read the qualification
A declared metre unit does not supply a missing calibration. If the original geometry scale was not verified, a distance computed from its vertices must not be advertised as a measured organ dimension.
Use appropriate evidence for dimensions
For a documented pipe quantity, inspect the identified measurement observation and workbook source. Use the model to locate and discuss shapes within its stated limitations.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
The notebook deliberately provides viewing controls without a physical measurement ruler.
The useful distinction. Coordinate consistency allows interchange; metrological validity requires additional evidence.
Keep the response and its domain together
An impulse response characterizes a specified source–receiver arrangement under particular conditions. Its association with a VAO should identify the exact signal realization, channel interpretation and the scene or measurement to which it belongs. Applying that response elsewhere is a modeling choice. A player needs an explicit policy for positions outside the measured or modeled domain, such as a declared fallback, instead of suggesting that one response captures every listening position.
| Record | What the reader needs | What it does not establish alone |
|---|---|---|
| Captured response | Measurement setup, positions, signal identity and processing lineage. | Validity at every source and receiver position. |
| Simulated response | Geometry, material and boundary assumptions, method and evaluation evidence. | A measured response of the historical room. |
| Acoustic metric | Quantity, unit, band axes, method, uncertainty and any cited standard edition. | Conformance merely because a standard is named. |
| Learned field or surrogate | Training and validation evidence, supported domain and derivation. | Reliable extrapolation to undocumented conditions. |
Cuntz · Illustrative scenario#
What would it mean to hear Cuntz in another room?
Auralization makes a modeled acoustic situation audible. An impulse response describes how a sound travels from a specified source position to a specified receiver under stated conditions.
Work through the example 3 STEPS
Imagine presenting a Cuntz recording as if heard in another room. This is a teaching scenario; no measured response for that proposed room is supplied by this notebook.
Identify the starting signal
Record the exact audio realization and its capture conditions. A microphone recording already includes effects of its original room and recording chain.
Identify the proposed room response
A measured or simulated impulse response has a source position, receiver position and method. Applying it through convolution combines the signal with that response over time; it does not erase the original recording conditions.
State the supported claim
The resulting sound demonstrates the chosen signal-processing arrangement. A claim about the instrument in a historical room would also require appropriate source, spatial and acoustic evidence.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
The Cuntz 3D preview does not implement auralization, and this example does not add an Acoustics profile declaration to the published package.
The useful distinction. Making an acoustic scenario audible is different from demonstrating that the historical scenario sounded that way.
Declare the capabilities the object actually uses
VAO 0.5.0 requires Core and Dynamic Delivery for every conforming object, including an embedded-only package. Additional profiles follow the represented capabilities: Multimodal Timeline for timebases and synchronized tracks, Spatial for frames and poses, Acoustics for relevant response or scene records, and Scientific for scientific records. Physical Instrument, Playable and Deterministic Runtime address further aspects when present. Profile declarations are not a promise that every client will execute every feature.
A useful inspection sequence is to read the profile declarations, identify required materialization groups, verify their availability, and then check the application’s implementation scope. A Blender importer may inspect a spatial package and load geometry without executing its acoustic behavior. A runtime capable of convolution still needs the correct responses, mappings and dependencies. The object contract and the application capability are both necessary to interpret what the user hears.
Compare VAO clientsInspection, geometry import, audio and interactive execution.
Connect a recording to its analysisPreserve regions, channels and acquisition context.
Cuntz · Released record#
Does showing the organ in 3D mean the VAO is playable?
A profile names a set of requirements for a capability. A client’s support describes what an application can do with the object; the two declarations must be compared.
Work through the example 3 STEPS
The Cuntz manifest declares Core, Dynamic Delivery, Playable, Physical Instrument, Scientific, Multimodal, Spatial and Zenodo Repository profiles under VAO 0.5.0.
Read the object’s declarations
The object contains information for several uses, including physical topology, scientific observations and sampled interaction. These requirements describe the package contract.
State the viewer’s operation
The notebook loads a GLB display derivative and provides camera controls. It does not import the full VAO manifest, evaluate its scientific records or execute its keyboard and stop behavior.
Choose another client when the task changes
To test sampled playback or synchronized controls, choose a client whose documented version supports the relevant format, profiles and resources. Record the tested operation separately from successful visual loading.
BASIS FOR THIS EXAMPLE
- Cuntz Positiv · VAO 0.5.0-rc.2 ↗
Published manifest: identities, measurement observations, realization digests, profiles and rights. Exact examples checked against this release.
- VAO Standard 0.5.0 ↗
The standard contract is separate from the Cuntz dataset content version 0.5.0-rc.2.
No acoustics profile or calibrated acoustic response is inferred from the presence of an organ model.
The useful distinction. A working 3D preview proves that the chosen model can be displayed; it does not establish complete VAO conformance or playability.
Sources & further reading
- VAO Standard 0.5.0
Normative standard, profile index, Dynamic Delivery Profile and conformance specification in the versioned release.
- Dominik Ukolov · Musikinstrumente im virtuellen Raum (2026)
Dissertation submitted to Universität Leipzig, 11 September 2026. Chapters 5 and 6; evaluation distinctions in §8.1.1, pp. 254–256. Page numbers refer to the printed manuscript pagination. The manuscript is not distributed by this website.
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