Were you in the habit of browsing the New Scientist? David Jones had a weekly column there in which he introduced various plausible and implausible inventions invariably wrapped in a story told to him by "my old friend Daedalus". One of these introduced the [im]plausible science of Archaeoacoustics, and was taken more seriously than most. Wikipedia notes:
[...Archaeoacoustics] was first raised in the 6 February 1969 issue of
New Scientist magazine, where it was discussed in David E. H. Jones's
light-hearted "Daedalus" column. He wrote:
[A] trowel, like any flat plate, must vibrate in response to sound:
thus, drawn over the wet surface by the singing plasterer, it must
emboss a gramophone-type recording of his song in the plaster. Once
the surface is dry, it may be played back.
Jones subsequently received a letter from one
Richard G. Woodbridge III who claimed to have already been working on
the idea and said that he had sent a paper on the subject to the
journal Nature. The paper never appeared in Nature, but the August
1969 edition of the journal Proceedings of the IEEE printed a letter
from Woodbridge entitled "Acoustic Recordings from Antiquity". In this
communication, the author stated that he wished to call attention to
the potential of what he called "Acoustic Archaeology" and to record
some early experiments in the field. He then described his experiments
with making clay pots and oil paintings from which sound could then be
replayed, using a conventional record player cartridge connected
directly to a set of headphones. He claimed to have extracted the hum
of the potter's wheel from the grooves of a pot, and the word "blue"
from an analysis of patch of blue color in a painting.
Many Daedalus columns were later published in two collections "Inventions of Daedalus: A Compendium of Plausible Schemes" (1982) and "Further Inventions of Daedalus" (1999). So that's another place you might have encountered it.
[I'm taking the liberty of including the text published in "The Inventions of Daedalus", just in case it jogs Alfred's memory - Clara DS]
Daedalus has been musing on the tantalizing aspects of dead languages, of how we can never tell how Latin or ancient Greek sounded from mere perusal of the written symbols. Little things give clues, like the phrase Aristophanes attributed to his frogs: ‘Brekekekex Koax Koax’ – always assuming Greek forgs have not extended their limited repertoire since his day. But what is really needed is some natural recording process by which ancient sound was authentically entrapped. Daedalus, impressed by the vocal artistry of his interior decorators, now believes that this is provided by the humble art of plastering. He points out that a trovel, like any flat plate, must vibrate in response to sound: thus, drawn over the wet surface by the singing plasterer, it must emboss a gramophone-type recording of his song in the plaster. Once the surface is dry, it might be played back by running a pick-up trowel over the surface in the same direction, though better fidelity could be achieved by first casting a more durable replica of the surface, or reconstructing the wave-form by microscopy.
So,here is a quite new and very powerful method of recovering the work-songs of ancient Greek plasterers. A rich vein of classical bawdy ought to be revealed in, e.g., the stucco of the palace of Knossos; respectable antiquarians given to voicing the hopeless plea, ‘If only these walls could speak!’ will probably be somewhat dismayed by their tone when they do. But much wider fields are open to Daedalus's new technique of archaeographony. Thus the dictation of letters taken down with the stylus on clay tablets must have left their vocal equivalent embossed into the tablet, together with informal expletives when the hapless scribe made a mistake. Daedalus hopes to examine the plaster of old Stratford on Avon and finally disprove the deplorable theory that Shakespeare spoke American, which language was transported by the Pilgrim Fathers to the States where it was fossilized, while we progressed towards modern BBC.
(New Scientist, 6 February 1969)