I haven't any here to try this on, maybe someone can save
me buying one and finding it doesn't work

The ISD chips have an XCLK input for an external clock. In
the datasheets and app notes, it states that the external clock
required to meet spec with, for example the 1416, is 1024kHz
to get the sample rate of 8kHz. This appears to be offered as
a solution for the variability of the internal oscillator which I
guess is RC because of the temperature and voltage dependence

I see no mention of using XCLK to change the sample rate/sound
length. Other sound chips I've used can have an external clock
applied that has fairly wide frequency range, with a consequent
change in sound length and quality. The difference is that these
chips use external memory, typically RAM or EPROM). Data
can be recorded to RAM even at fast clock speeds or pre-
loaded in EPROM . The ISD chips possibly won't record
properly at a faster speed due to the internal timing requirements
of their EE cells, but is it possible to record at a slower speed ?

For example (I know there are 20 second versions available)
if I wanted to squeeze 18 seconds into 1416, could it be sped
up in an audio processor to take 16 seconds, recorded with the
internal 1024kHz and played back with a 910kHz XCLK ????

Practical experiences welcomed - TIA

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