IOI 350ms took me little time to memorize as it is the slowest "melody
specific" isotempo. Whenever unsure, I used to compare it to IOI around 400ms
(i.e. corresponding to the fastest rate of sustainable attention shift
and the first fully-fledged "beat specific" isotempo). To my
perception, the difference between the two neighbouring isotempi is
immense so it's hard to miss it. Despite that, I accept that it is hard
to differentiate it when compared to IOI 300ms, as the "glueing" effort
in legatissimo performances (see previous blog-entry) is in both cases great.
Whereas IOI 250ms is considered by scholars to be the borderline
between holistic versus analytical brain-processing of neighbouring
pulsations, IOI 350ms can be viewed as the borderline between "melody
specific" and "beat specific" isotempi.
There is no oddity to have a MM 170 (corresponding to IOI 350ms) mark
on a musical score. As a matter of fact, classical metronomes display,
as the fastest "beat specific" isotempo, the MM 200 mark, corresponding to IOI
300ms – that meaning that good old common-sense worked well before
cognitive musicology and experimental psychology were invented. At IOI
250ms it becomes already hard to consider the specific pace a
"beat-rate". At IOI 300ms also, but speed maniacs may consider it an
option.
At IOI 350ms we can view the specific pace as a kind of
temporal mule (i.e. neither horse, nor donkey), meaning that we can
imagine it as both melody-specific or beat-specific. Do not mistake the
term "beat-specific" for that of "first sustainable rate of
attention-shift" as the first refers to classical rhythm theory and
encompasses IOI values from 300ms up to around 1500ms (look at a
classical metronome) whereas the latter refers specifically to IOIs
around 400ms.