5.5 KiB
Phase 2: Audio Synthesis Engine - Discussion Log
Audit trail only. Do not use as input to planning, research, or execution agents. Decisions are captured in CONTEXT.md — this log preserves the alternatives considered.
Date: 2026-03-26 Phase: 02-audio-synthesis-engine Areas discussed: Tone mapping, Waveform texture, Amplitude dynamics, Mixing & headroom
Tone Mapping
Frequency range
| Option | Description | Selected |
|---|---|---|
| Narrow ambient (80-400 Hz) | Deep, bass-heavy drones — everything in warm low register | |
| Wide ambient (60-800 Hz) | Spread across bass to mid range — rich, layered soundscape | ✓ |
| Full spectrum (50-2000 Hz) | Bass through high-mid — maximum separation |
User's choice: Wide ambient (60-800 Hz) Notes: None
Register assignment
| Option | Description | Selected |
|---|---|---|
| Keep as shown | HTTPS at ~175 Hz is low enough for bulk drone feel | ✓ |
| Swap to match prior rule | Strictly follow bulk=low, control=mid, interactive=high | |
| You decide | Let Claude optimize Hz values |
User's choice: Keep as shown Notes: None
Tuning approach
| Option | Description | Selected |
|---|---|---|
| Musical intervals | Harmonic/musical relationships so layers blend pleasantly | ✓ |
| Arbitrary spacing | Spread evenly, simpler but may clash | |
| You decide | Claude picks |
User's choice: Musical intervals Notes: None
Unknown traffic tone
| Option | Description | Selected |
|---|---|---|
| Single fixed tone at top of range | Always ~800 Hz | |
| Dissonant/detuned tone | Off-key or beating frequency signals unclassified traffic | ✓ |
| You decide | Claude picks |
User's choice: Dissonant/detuned tone Notes: None
Waveform Texture
Richness
| Option | Description | Selected |
|---|---|---|
| Pure sine waves | Clean, minimal, ethereal — single frequency per class | |
| Sine + 2-3 harmonics | Fundamental + overtones — warm, pad-like, textured | ✓ |
| Unique waveform per class | Different harmonic profiles per traffic type |
User's choice: Sine + 2-3 harmonics Notes: None
Harmonic ratios
| Option | Description | Selected |
|---|---|---|
| Same ratios everywhere | All classes use identical harmonic recipe | |
| Vary per class | Each class gets different harmonic weights for timbral distinction | ✓ |
| You decide | Claude picks |
User's choice: Vary per class Notes: None
Amplitude Dynamics
Responsiveness
| Option | Description | Selected |
|---|---|---|
| Slow, glacial (2-4 sec) | Layers swell and fade gradually like weather | |
| Medium (1-2 sec) | Noticeable response, still smooth | ✓ |
| Snappy (0.5-1 sec) | Layers track traffic closely, more reactive |
User's choice: Medium (1-2 sec) Notes: None
Zero-traffic behavior
| Option | Description | Selected |
|---|---|---|
| Fade to full silence | Only active traffic produces sound | |
| Fade to a whisper | Barely-audible trace remains for any seen protocol | ✓ |
| You decide | Claude picks |
User's choice: Fade to a whisper Notes: None
Whisper floor type
| Option | Description | Selected |
|---|---|---|
| Fixed floor | Once seen, stays at fixed very-low amplitude (2-5%) | ✓ |
| Recency-based decay | Whisper fades further over time based on recency | |
| You decide | Claude picks |
User's choice: Fixed floor Notes: None
Mixing & Headroom
Mix strategy
| Option | Description | Selected |
|---|---|---|
| Fixed equal gain | Each layer gets 1/N headroom (~0.09 max) | ✓ |
| Weighted gain by priority | Bulk traffic gets more headroom | |
| Dynamic limiter | No fixed gain, soft-clip if exceeds headroom |
User's choice: Fixed equal gain Notes: None
Sample rate
| Option | Description | Selected |
|---|---|---|
| 44100 Hz (CD quality) | Standard, LAME native | ✓ |
| 22050 Hz (half rate) | Smaller files, still fine for <800 Hz | |
| You decide | Claude picks |
User's choice: 44100 Hz Notes: None
MP3 bitrate
| Option | Description | Selected |
|---|---|---|
| 128 kbps | Good quality, ~1 MB/min | ✓ |
| 192 kbps | Higher quality, ~1.5 MB/min | |
| You decide | Claude picks |
User's choice: 128 kbps Notes: None
Channel mode
| Option | Description | Selected |
|---|---|---|
| Mono | Single channel, simpler | |
| Stereo with panning | Each class panned for spatial separation | ✓ |
User's choice: Stereo with panning Notes: None
Panning approach
| Option | Description | Selected |
|---|---|---|
| Fixed positions by register | Bass center, mid spread, high wider | ✓ |
| Even spread | All 11 evenly from hard L to hard R | |
| You decide | Claude picks |
User's choice: Fixed positions by register Notes: ICMP center, DNS slight-L, HTTPS slight-R, etc.
Claude's Discretion
- Exact Hz values per class (within 60-800 Hz, musical intervals)
- Specific harmonic ratios per traffic class
- Exact EMA alpha/decay constants for 1-2 sec feel
- Exact whisper floor percentage (2-5%)
- WAV intermediate format usage
- Stereo panning implementation method
Deferred Ideas
None — discussion stayed within phase scope