A product's sounds are a type family, not a clip-art folder. Pick one material — a struck wooden bar, a soft plastic tap, a breath of filtered noise, a muted glockenspiel — and derive every sound from it, the way a palette derives every tint from one hue in color-monochromatic. Five sounds that share a material feel like a product. Five sounds from five packs feel like a browser toolbar from 2003.

The grammar

Earcons (Blattner, Sumikawa & Greenberg, 1989) are learned, not mimetic: meaning comes from contour and interval, and users learn it in a handful of exposures.

Dimension	Rule	Why
Size → pitch and length	Small elements tick high and short (2–6 kHz centroid, 40–120 ms). Big elements land low and long (0.8–1.5 kHz, 300–800 ms).	Physics. A card is lighter than a wordmark; the ear knows.
Direction → meaning	Rising figure = success, open, join. Falling = dismiss, leave, error.	Discord's join/leave pair; every OS you have used.
Interval → valence	Major third or perfect fifth for confirmation. Minor second or tritone for error.	Consonance reads as safe; dissonance as tense (IWC study on earcon dissonance and perceived hazard).
Complexity → priority	Simple, single-hit for frequent actions. Multi-note only for rare or urgent moments.	Frequent complex sounds fatigue in a day (Toptal).
Repeat → variation	A run that counts (pops, stacking blocks, dings) steps pitch up (`playbackRate` +5–10% per hit, about +1 st). A run that repeats (keys, steps) cycles 4+ recorded takes, never the same twice in a row, ±1–2 dB, at most ±3 % (½ st) of pitch. The click is the exception: one voice, one level, every time.	Identical repeats read as a machine; Josh Comeau's "glug" pattern. Random pitch on typing is its own tell: real keys vary in take, not pitch (designed-sfx-anatomy).

A minimal family

Most products need four to six sounds, not forty:

Name	Role	Shape
`tick`	Toggle, select, snap	Single transient, ≤ 80 ms, high
`tap`	Primary press in tactile products only	Dull transient with a short body, ≤ 120 ms
`send`	Send / save / complete	One or two notes rising, ≤ 250 ms
`receive`	Incoming message / notification	Two notes, lower than `send`, ≤ 400 ms
`error`	Rejected submit, invalid drop	Low, falling, ≤ 200 ms — paired with multi-segment-shake
`success`	Rare milestone	Three-note figure in the family's key, ≤ 800 ms

Write the family down as a manifest before generating anything — scripts/sound-family.mjs next to SKILL.md takes exactly this shape and produces the files via sound-generation-elevenlabs or the built-in synth from sound-generation-open-source.

Material, not genre

Apple's sound team records real instruments — glockenspiel, kalimba, marimba — and even struck a hollow Apple Watch case with mallets to find its resonance. "Organic over futuristic" is the stated reason: familiar materials make new technology comfortable. The AI-default failure is the opposite — a glossy sci-fi "digital UI blip" that belongs to no product. Describe a thing (soft felt mallet on a wooden bar; a fingernail on glass; a breath through a paper cone), never a style.

When to apply

Before generating or downloading a single file. Decide the material, list the family, then produce. Reviewing a product with sounds: ask whether they share a material; if not, that is the finding.

Gotcha

Do not tune the family in isolation with headphones at midnight. Laptop speakers have nothing below ~200 Hz, so a warm low thud disappears and a bright tick becomes a needle. Design in mono, check on the worst speaker in the office, then set levels per sound-spec.

Sources

Blattner, Sumikawa & Greenberg (1989), Earcons and icons — structured families of tones whose contour carries meaning.
Perceived Hazard of Earcons in IT Exception Messages (Interacting with Computers, 2013) — consonance/dissonance and pitch drive perceived urgency.
Twenty Thousand Hertz, The Sound of Apple (Hugo Verweij) — real instruments, organic over sci-fi, the Watch case experiment.
Toptal, A Quick Guide to Designing UX Sounds — simple for frequent, complex for high-priority; mid-range frequencies.
Josh Comeau, use-sound — rising playbackRate on repeats.
Leon Lin, earshot (MIT): skills/real-sound/references/sound-design.md §6 — take pools cycled, ±1–2 dB, ±0.3–0.5 st at most, the one-voice click.
Related: color-monochromatic, typography-humanity, ai-default-tells.