SLOP3255 · Week 06 · Audification
The gravitational-wave chirp#
The rising pattern belongs to the event. The playback volume, filtering and pitch range belong to the rendering.
Start with the measured claim#
The detector output is a calibrated time series, not a microphone recording.
Source: LIGO GW150914 event record
From arm length to event window#
The signal is extremely small and always encountered inside detector noise.
Why it is called a chirp#
As the black holes spiral together, gravitational-wave frequency and amplitude rise. Merger ends the rising pattern.
Three renderings, three claims#
| Rendering | Operation | Consequence |
|---|---|---|
| Calibrated window | direct playback path | closest to timing, difficult to hear |
| Filtered + amplified | reduce selected noise bands | pattern clearer, context altered |
| Frequency shifted | move spectrum upward | audible detail, measured band changed |
Clarity and fidelity are related, not identical.
Two detectors are part of the evidence#
Hanford
One strain series, local detector noise and quality state.
Livingston
A second series with compatible event timing and shape.
Hearing only a polished combined chirp removes the cross-site comparison that helped support the detection.
Let noise remain visible#
Before
nearby detector noise
During
candidate event window
After
return to local noise
Compare all three. Ask which features persist after processing and which depend on a chosen filter.
Disclosure before drama#
| Publish | Name precisely |
|---|---|
| source | detector, event identifier, retrieval date |
| selection | time window and quality exclusions |
| processing | filters, thresholds and amplitude scaling |
| playback | speed and frequency changes |
| additions | any music, reverb or spatialisation |
If the operation cannot be reconstructed, the legend is incomplete.
Listening Lab 06 · Output: processing ladder
Order the chirps#
Task
Order three GW150914 renderings by processing intensity, then justify the order with their spectrograms.
Deliver
- operation list
- audible evidence
- bounded claim
Reference: LIGO · ligo.org/detections/gw150914/