Was heard to have checked the depth (7)

I believe the answer is:

sounded

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'checked the depth' is the definition.
The definition and answer can be both related to change as well as being past participle verbs.
Maybe you can see a link between them that I don't see?

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(Other definitions for sounded that I've seen before include "did some probing" , "Found the depth of" .)

I've seen this clue in the Evening Standard.

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