SLOP3255 · Week 05 · Time–frequency data
The noisy Sun#
A bright streak can be a solar burst, local interference, an instrument effect—or not enough evidence.
A dynamic spectrum has three variables#
Audio unfolds in one time dimension. We must decide how the second axis enters the listening experience.
Read the picture before mapping it#
High radio frequency
Middle radio frequency
Low radio frequency
Ask whether a feature is narrowband, broadband, vertical, drifting or persistent. Geometry suggests—but does not prove—cause.
Different shapes imply different questions#
| Visible pattern | Possible reading | Auditory test |
|---|---|---|
| fast frequency drift | changing emission region | does pitch sweep over time? |
| vertical broadband line | short event or impulsive RFI | does it appear across channels together? |
| persistent narrow band | local transmitter candidate | does one pitch remain fixed? |
| blank rectangle | missing data or receiver state | is absence explicitly marked? |
Pattern recognition generates hypotheses. Metadata and comparison test them.
Not every bright feature is solar#
Radio-frequency interference
- may remain at fixed local frequencies
- may begin or end abruptly
- can overwhelm astrophysical structure
Solar candidate
- compares across observatories
- fits plausible drift behaviour
- survives instrument-quality checks
The sonification should not turn a classification guess into certainty.
Three routes through the same matrix#
Each route discards structure. The legend must say which structure survives.
Silence can mislead#
Zero
The instrument measured no signal above its defined baseline.
Missing
No valid measurement exists for this interval.
Muted
The designer chose not to render a valid value.
These states may all sound quiet, but they make different claims.
Make the quality channel audible#
| Data state | Primary sound | Quality cue |
|---|---|---|
| valid sample | mapped tone | none |
| suspected RFI | mapped tone | dry click or timbre marker |
| missing interval | no mapped tone | explicit gap cue |
| clipped receiver | bounded tone | warning layer |
Quality should not compete with the main scientific pattern, but it cannot disappear.
Listening Lab 05 · Output: classification card
Noise or event?#
Task
Compare three synthetic dynamic spectra and their row-scan audio. Classify each feature with a confidence level.
Evidence
- shape
- quality flags
- cross-station check
Reference: CSIRO Space Weather Services · solar radio observations