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I have a query concerning polystyrene plastic. This polymer makes a
distinctive ‘clank’, or tinkling sound when dropped on a hard surface. It
does this whether in the form of a solid, an alloy (ABS) or, remarkably,
an expanded foam.

Is there a scientific reason for this, and are there other plastics
which may be identified by their distinctive sounds?

F. G. Grisley Barry, Glamorgan