The Silent Millimeter

The silent millimeter is this site's name for a dimension in an instrument's construction that you cannot judge by looking, but that measurement shows changing the sound the instrument produces. The dimension is silent in the sense that nothing about its appearance announces it. The term is a metaphor, not a scientific term, and the millimeter is a figure of speech, not a size limit.

Stated without the metaphor: a small difference in size or position, which an acoustic measurement shows changing an instrument's output.

The term steers which construction details the Instruments entries examine.

Measurably different is not audible

A dimension qualifies only when a measurement shows that the output changes with it, for example a recorded spectrum that differs when the dimension differs.

When the only evidence is a difference in the spectrum, the entry calls the result measurably different. It does not call the difference audible.

An entry says a difference can be heard only when a listening experiment with people supports it, such as a test of the smallest change listeners can detect, or a blind comparison in which listeners judge which of two sounds matches a third. The entry then says who listened and under what conditions.

What it is not

It is not a verdict on tone. The term marks that something measurable changed, not that the result sounds better or worse.

It is not a buying guide. A silent millimeter explains how an instrument makes its sound, not which instrument to choose.