Here is what I did: I went out on sort of a windy day and started my truck, raised the hood and removed a corner of my phone from it’s protective case. I made three separate audio clips about one minute each:
1. F150 Truck Engine Acoustic - (Bare corner of phone touching the valve cover) at Idle
2. F150 Truck Engine Airborne Acoustic - (Phone held about one foot above the engine) at idle
3. F150 Truck Electrical Fuse Box Acoustic - (Bare corner of phone touching fuse box) at idle
I used the voice recorder app on my phone. So easy! Below is the analysis. Also, Creating an audio file of slowly revving the engine would increase the report detail.
This is a small real-world example of what ASI can do. If you have one recorded file tied to one real problem, send it. If we can read it, we can analyze it. Your first analysis is free. When you gather what data you have and are ready, Click Here
Ford F-150 Engine Acoustic Analysis Report
ITAR Screen Result
CLEAR.
Uploads screened: CLEAR. Intermediate artifacts screened: CLEAR. Final report screened: CLEAR. Indicators reviewed: civilian Ford F-150 engine/fuse-box acoustic captures only; no weapons-system data, no military platform details, no controlled defense performance data, and no export-controlled technical content detected.
Executive Summary
Duration analyzed: 200.98 s total across 3 files. Grouped notable events/signatures: 6. Overall data quality: moderate.
Primary question status: partially answered. The recordings consistently show a stable low-frequency engine-order-like component near 54–65 Hz plus persistent narrowband tonal families near about 430–530 Hz and about 1.2–2.0 kHz. This is more consistent with normal or near-normal idle plus accessory/electrical tonal content than with severe random mechanical distress. A clearly isolated heavy knock, scrape, or strong bearing-rumble signature was not established in these files.
Data Characteristics
Format: MP3, mono, 44.1 kHz, nominal 128 kb/s.
Files and durations: 1) Engine Acoustic 92.47 s; 2) Engine Airborne Acoustic 49.34 s; 3) Electrical Fuse Box Acoustic 59.19 s.
Noise/integrity notes: no sustained clipping detected. Brief MPEG resync artifacts were present in all three files, consistent with compressed/mobile capture. Low-frequency electrical/engine hum is strong. Handling or position-change effects are likely near the ends of files 1 and 2. Spectral content above roughly 10–15 kHz is not treated as diagnostic.
Environment notes: land vehicle, Ford F-150 engine-area screening. No RPM, load, hot/cold state, exact placement, or coupling metadata was provided.
Detected Events
- 00:00–end across all files — Stationary low-frequency tonal bed. Dominant bands: about 54 Hz (files 1 and 3) and about 59–65 Hz (file 2), with harmonically related energy. Pattern: steady, engine-order/electrical-hum-like. Confidence: 82%. Evidence: narrow persistent peak structure with low drift over multi-second windows.
- 00:00–end, strongest in files 1 and 3 — Persistent mid-band tonal family near about 430–530 Hz. Pattern: stable narrowband tone with nearby harmonics/partials. Confidence: 76%. Evidence: repeated spectral peaks around about 430–506 Hz across 5 s windows.
- 00:00–end, strongest in files 1–3 — Upper tonal family near about 1.2–2.0 kHz. Pattern: steady tonal/whine-like content, location-dependent amplitude. Confidence: 71%. Evidence: recurring peaks near about 1.2–1.7 kHz in files 1 and 3 and about 1.9–2.0 kHz in file 2.
- About 48–49 s in file 2 and about 68–71 s in file 1 — Brief amplitude surges. Pattern: short broadband level increases rather than new sustained tones. Confidence: 63%. Evidence: RMS excursions without durable frequency reorganization; likely mic movement, proximity change, or brief operating-state disturbance.
- Intermittent in file 3, especially about 2–21 s — Short impulsive/ticking events over steady background. Dominant bands: broadband with low-/mid-band emphasis. Confidence: 58%. Evidence: repeated short high-RMS segments in the fuse-box capture, not persistent enough to classify as continuous fault noise.
- File 3 versus files 1–2 — Elevated low-frequency electrical/structure-coupled emphasis at fuse box. Pattern: stronger below-200 Hz component with reduced very-high-frequency energy. Confidence: 74%. Evidence: band-power shift and lower spectral-centroid mean relative to the engine-bay airborne capture.
Classification Summary Table
| Event/Group | Source Type | % of Events | Confidence % | Conf Level | Notes |
|---|---|---|---|---|---|
| Idle/order tonal bed | Engine order / idle combustion | 40% | 82% | High | Stable ~54–65 Hz bed; likely idle-related content |
| Mid-band tonal family | Accessory or structural resonance | 20% | 68% | Moderate | Persistent ~430–530 Hz narrowband tone |
| Upper tonal family | Accessory/electrical whine | 15% | 64% | Moderate | Steady ~1.2–2.0 kHz tonal content |
| Fuse-box low-freq emphasis | Electrical coupling / panel resonance | 10% | 74% | High | Stronger <200 Hz content at fuse-box location |
| Intermittent ticking | Relay/actuator or incidental transients | 10% | 58% | Moderate | Short impulses in file 3; not continuous |
| Brief broadband surges | Handling / position / brief state change | 5% | 63% | Moderate | Late-file level surges without new stable lines |
Limitations & Assumptions
- RPM/load was not provided, so engine-order mapping is approximate. A component near 54 Hz could correspond to roughly 800 RPM only if the assumed firing/order relationship is correct.
- Microphone placement/coupling is unknown. Airborne versus structure-coupled pickup can strongly change the prominence of fuse-box, harness, cover, and bracket resonances.
- MP3 compression and brief decode/resync artifacts reduce confidence for weak impulsive events and fine sideband interpretation.
- Propagation effects are material: hood reflections, panel radiation, and hand-held movement can create or exaggerate tones not originating at the suspected component.
- No tach, synchronized load changes, healthy baseline, or vibration data were available, so fault attribution remains conservative.
Recommendations
- Record uncompressed WAV at fixed placement for idle, 1,500 RPM, and 2,500 RPM. If the ~54–65 Hz and ~430–530 Hz lines scale with RPM, they are more likely engine-order/accessory related than random electrical buzz.
- Inspect the accessory drive: belt condition, belt tracking, tensioner damping, idler pulley roughness, alternator pulley/freewheel (if equipped), and A/C clutch. The stable ~430–530 Hz family plus upper whine content is compatible with accessory-related tonal radiation.
- Check charging-system health: alternator ripple, battery terminals, engine/body grounds, and fuse/relay seating. The fuse-box recording shows stronger electrical/structure-coupled content and intermittent ticks that justify a power/ground and relay-buzz screening.
- Re-record with closer source separation: one mic near front accessory drive, one near intake/fuel rail, and one at the fuse box. Keep placement fixed and log hood open/closed, hot/cold, A/C on/off, blower on/off, and lighting load.
- If the concern is a mechanical knock, use a controlled change test by a qualified technician: accessory load changes, repeatable RPM holds, and higher-quality audio. These files do not establish a severe knock or strong bearing rumble.
- Service priority: 1) verify charging/ground integrity, 2) inspect belt/tensioner/idlers/alternator, 3) re-record under controlled RPM/load, 4) escalate to deeper mechanical inspection only if a repeatable tone, tick, or load-sensitive roughness remains.