Spectra already resemble timelines, but the horizontal axis is wavelength, not
time. Playing left to right creates a temporal sequence. We use a reference
tone and spoken axis markers so listeners can compare line position without
assuming that consonance carries scientific meaning.
Wavelength and flux pairs → preserve or transform wavelength spacing → map flux
to level → add axis landmarks → compare shifted copies. Any logarithmic
transform is stated in the legend.
The lab evaluates whether a listener can identify a known shift, not whether
the spectrum produces an attractive scale.
Observation guide 08
Spectral comparison
Use this page before the slides, then return to the checkpoint after the lab.
After this week, you can
Keep wavelength separate from playback time.
Use reference cues without converting scientific intervals into harmony claims.
Compare spectral-line positions under a stated scale.
Inspectable teaching model
relative flux
0.080.120.180.760.200.130.100.08
Two schematic spectra sampled on the same wavelength grid. Values are a teaching model, not an astronomical observation.
Worked notebook
Locate a shifted emission line
Two schematic spectra sampled on the same wavelength grid.
Keep both spectra on the same wavelength axis.
Play the first left to right with spoken axis landmarks.
Alternate the shifted copy without changing scale or duration.
Ask listeners to report direction and approximate size of the shift.
What the method supportsPlayback order represents increasing wavelength, not elapsed astronomical time. A successful listener can compare line position without treating the resulting interval as physical harmony.
CheckpointWhat new structure appears the moment a static spectrum is played from left to right?Reveal the reasoning
The designer creates a temporal order from the wavelength axis.
The spectrum already has ordered wavelength samples, but it does not unfold in listening time. Playback makes that axis sequential, so duration and tempo must appear in the disclosure.