In reply to your message dated 29/08/2009 at 16:18
Dear Diana, and list,
Thanks for your personal comments. You noted:
Philip Vernon wrote an entertaining article about his shift of AP
with
age in the British Journal of Psychology 1977, 68, 485-489.
I found the article in my reprint collection, but inside I found a
letter
from Philip Vernon which accompanied the reprint, dated September
19, 1978. He would then have been aged 72. Rereading the article
he specifically suggested how his experience is consistent with a
change in stiffness of the basilar membrane.
One of his comments to me echoes your own comments about
variability:
"My own hearing is, I would say, quite normal, apart from some
natural tendency to deafness with age. But the deviance of my
pitch norms is quite liable to fluctuate. E.g., at an ordinary
orchestral
or chamber concert, I may start off identifying the keys a semitone
too
high, and then notice half-an-hour later that everything is a tone too
high; sometimes, of course, I am uncertain of which is predominant.
But I don't seem to find any fluctuations with health, colds, or other
conditions. (Signed: Philip E Vernon)"
-----
So he seems to be suggesting that the same underlying parameter
varies in the short-term as well as with age. Perhaps the same
parameter explains the variation of AP with menses (Wynn, 1971) ?
Andrew Bell (HR1992) also showed that spontaneous OAE
frequencies also shift with menses, again suggesting a link
with cochlear mechanical stiffness. Recently I showed a post-hoc
analysis of CEOAEs suggesting a possible diurnal variation in the
whole-waveform reproducibility (p<0.01) (Acoustics Australia
April 2006). David Kemp did a prospective study (reported at
the 2008 mechanics meeting in Keele) and concluded there was
a diurnal variation in CEOAEs. Food for thought.
Regards,
ELeP
www.oaericle.com.au