George Marshall:

>I've just been told by my partner that she read somewhere that using
>headphones, even at low levels, spoils your hearing because parts of
>your hearing system become, in effect, redundant.  Tell me this isn't
>true, somebody please.

 From what I've heard, you can rest easy.  I sympathize with the wish to
scare people from misusing them: after all, just about everyone during
your commute wears earphones now, and the volumes are sometimes up so
high as to interrupt one's reading.

All the same, from what I've read ears can take quite a bit of sonic
punishment, even from earphones.  Reasonably loud volumes are ok, but
not for long.  Aside from persistently high volumes, sudden changes to
a high volume can also damage auditory health.  So one can cope with
a moderately high volume, but get there gradually.  Even then, that's
against a quiet backdrop: a third type of damage is if your volume's
turned up loud to squelch a noisy street environment: you can also
count on some damage then.

Bert Bailey, in Ottawa