Robert Morein
March 23rd 06, 10:47 PM
If you wear glasses, they serve as secondary diffraction sources.
One of the early developments of wave theory, in the 16th century, by
Christian Huygens, sought to explain the phenomena of diffraction. Perhaps
you have seen ocean waves spread out past the end of an ocean breakwater.
Huygens provided a method of determining the geometry, though not the
magnitude, of wave propagation, with the observation that the edge of the
breakwater, as well as any other sharp boundary, appears to behave like a
point source of new wave propagation. Thus, when a wave, be it an ocean
wave, or sound wave, encounters the edge of an obstacle, new waves occur in
different directions from the original source.
Because glasses have edges, and the size of glasses is somewhat more than
the wavelength of sound above 3 kHz, the edges of the glasses serve as
secondary diffraction sources for these higher frequencies, interfering
with one of the mechanisms of sound localization. Thus, a wearer of glasses
loses a little bit of the opportunity to comprehend the sound field. This
applies to live perfomances as well as reproduction.
I find that removing my glasses makes things a little bit better. In the
case of a live performance, this deprives me of the opportunity to
completely witness the performance. But with reproduction, there is no such
drawback.
One of the early developments of wave theory, in the 16th century, by
Christian Huygens, sought to explain the phenomena of diffraction. Perhaps
you have seen ocean waves spread out past the end of an ocean breakwater.
Huygens provided a method of determining the geometry, though not the
magnitude, of wave propagation, with the observation that the edge of the
breakwater, as well as any other sharp boundary, appears to behave like a
point source of new wave propagation. Thus, when a wave, be it an ocean
wave, or sound wave, encounters the edge of an obstacle, new waves occur in
different directions from the original source.
Because glasses have edges, and the size of glasses is somewhat more than
the wavelength of sound above 3 kHz, the edges of the glasses serve as
secondary diffraction sources for these higher frequencies, interfering
with one of the mechanisms of sound localization. Thus, a wearer of glasses
loses a little bit of the opportunity to comprehend the sound field. This
applies to live perfomances as well as reproduction.
I find that removing my glasses makes things a little bit better. In the
case of a live performance, this deprives me of the opportunity to
completely witness the performance. But with reproduction, there is no such
drawback.