The spectrum of sound is generally accepted as 20 Hz to 20000 Hz. If
we use 341 meters/sec as the speed of sound in dry air then the
wavelength of sound spans 0.017 meters to 17 meters. In reality,
speech can be understood between 20 and 2000 Hz. And as we age the
upper limit decreases. Most TV sets emit a 17,500 Hz audio sound from
the high voltage transformer. Only young children can sometimes hear
this. And kids are using at 17,000 Hz ringtone for their cell phones
that teachers can not hear but the kids can. This allows them to use
their cells (usually for texting) in the classroom without the
teacher knowing.
The mechanism of reception in animals is very different. In light,
there is a conversion from electromagnetic energy contained in the
light (electomagnetic) wave to electrical energy in the retina
through a photochemical reaction. In sound there most of the energy
is in the form of mechanical energy in the vibratory motion of the
medium (usually air) through which the sound wave is transmitted, to
the mechanical motion of the bones in the middle ear to electrical
energy.
There is no "type" of sound. All sound is the mechanical vibration of
a medium.
From a "sense and perception" standpoint, their is some evidence for
almost a universal emotion response to some sounds. I remember a
video that I had used in the past (can't remember the name), in which
a researcher created a series of sound and went around the world
asking subject to respond with a emotion that they felt when they
heard the sound. He claimed that there were cross-cultural
similarities in responses to these tones.
Ray Rogoway
[EMAIL PROTECTED]
On Sep 28, 2007, at 8:57 AM, <[EMAIL PROTECTED]>
<[EMAIL PROTECTED]> wrote:
Often times in texts there is an image of the spectrum of
electromagnetic energy with vision limited to the range of about
350-750 nanometers of wavelength. I try to tell students that there
the classroom is literally filled with all kinds of wavelengths
bouncing around; some we can see, some we can hear and some are
there but we are not consciously aware of them.
Now I wondering in preparing today's lecture, where in the
spectrum, by comparison, would sound waves fall, relative to the
wavelengths that we "see". Certainly the receptors must be tuned to
particular wavelengths with sound usually discussed in decibels or Hz.
But here is a real ignorance of physics on my part: is there a
comparison of sound and light wavelengths that we can talk about in
terms of the human psychological abilities of vision and audition?
If vision is 350-750 nanometers of wavelength, what is the type of
sound humans can perceive?
Thanks for filling in my deficient knowledge (I took chemistry for
my core in college, ha ha! no physics :(
Annette
Annette Kujawski Taylor, Ph.D.
Professor of Psychology
University of San Diego
5998 Alcala Park
San Diego, CA 92110
619-260-4006
[EMAIL PROTECTED]
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