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Reading the data · Project rules

ToneWood Acoustic Score

What does a score of 100 actually mean?

Acoustic Score is a versioned screening rule with explicit reference values. It is neither a percentile nor a universal material-quality law, and raw scores from different parts are not one ranking.

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Start with something familiar

A route planner can favour speed, low cost or fewer transfers. Its ranking depends on the declared goal. Acoustic Score is also a specified preference rule, not a natural law with a universal winner.

Reference ratios

E′ · reference factor = 1ρ · reference factor = 1Q · reference factor = 1

Top: modulus, density and Q factors

Versioned rule

100 × 1 × 1 × 1100No required Q → no score

100 is the reference, not a ceiling

Diagram · Reference ratios enter a versioned rule to produce a component score. A score is not a percentile or a predicted recording.

  1. Notice what changes

    Begin with the component. A top and a back use different rules because the project sets different screening preferences. Their raw scores should not be placed in one mixed ranking.

  2. Understand why

    A reference point defines the scale. For top and back, 100 means the stated reference combination; it is not a ceiling or proof of perfection. Missing required Q means no computable score.

  3. Connect it to wood and making

    Keep factors and model version with the number. A future rule change can change the score without changing the wood. A useful score makes assumptions visible rather than hiding them.

Put names to the ideas

01

Reference, not ceiling

The v4 soundboard rule multiplies normalized radiation ratio R/R₀ by Q/120. R₀ = √(12 × 10⁹/420)/420 ≈ 12.7267 m⁴/(kg·s), derived from E′ = 12 GPa and ρ = 420 kg/m³; calculations use the unrounded reference. This combination gives 100; soundboard and back scores may exceed 100.

02

Part-specific assumptions

The back rule combines speed, Q and a density preference centred on 620 kg/m³. That centre is a ToneWood model choice, not a universal optimum established by a paper.

03

Keep missing Q missing

Top and back rules require a valid Q; no value means no score. Simpler rules for other parts use different screening assumptions and should not be interpreted as finished-instrument evaluations.

Stop=100RR0Q120,R=cρ,R0=12×109/420420S_{\mathrm{top}}=100\frac{R}{R_0}\frac{Q}{120},\qquad R=\frac{c}{\rho},\quad R_0=\frac{\sqrt{12\times10^9/420}}{420}

Each ratio compares one input with its reference. An exponent controls how strongly that input contributes; multiplying the factors gives the top score. The numbers are project settings, not universal physical constants.

A worked example

The calculator shares the same R × Q rule as the database. At fixed R, doubling a valid measured Q doubles the soundboard score; missing R or Q leaves the score unavailable. The Ashby impedance-preference slider is a separate local exploration and never changes saved scores.

Explore it yourself

Choose a part, load its reference and change one input. Toggle missing Q to see which rules depend on a damping measurement.

TEACHING MODEL · LOCAL CALCULATION
Acoustic Score
100.0
E′ = ρc²
12.00 GPa

100 × radiation: 1.0000 × Q: 1.0000 = 100.00

All current component rules

C(x) = min(1, max(0, x)). E′ in Pa, density in kg/m³ and speed in m/s. Top and back have no upper clipping; the other rules use clipped factors.

Soundboard100E′/(12×109)(420/ρ)Q/120100\sqrt{E'/(12\times10^9)}(420/\rho)\sqrt{Q/120}
Back100(c/4000)1.5Q/100exp⁡[−4ln⁡2(ρ/620)]100(c/4000)^{1.5}\sqrt{Q/100}\exp[-4\ln^2(\rho/620)]
Sides100C((ρc−1.5×106)/(3×106))100C((\rho c-1.5\times10^6)/(3\times10^6))
Neck / bridge100C((c−3500)/3000)100C((c-3500)/3000)
Bass bar / bow / other50[C(c/6000)+C((c/ρ)/15)]50[C(c/6000)+C((c/\rho)/15)]

Local model version: euler-bernoulli-v1+soundboard-rq-v4+back-cq-density-v1

Check your understanding

Must a top score above 100 be a calculation error?

References

← All entriesRead Wood Acoustics →Explore the material library →