nid wrote:
ummm.... as I was sayin'
"Probably the sound most of us associate with lions is the snarl of the MGM lion, a deep, dangerous sound accompanied by lots of teeth. But lion roars are really sequences of three distinct types of "elements." They start soft and low with moan-like "prelude" elements, escalate into high-energy "roar" elements that begin at a frequency of about 240 Hz and drop to around 120 Hz, the "aaaouu" of Norm, then end with "grunts"--staccato "huh, huh, huh"s. Being staccato, with sharp beginnings and endings, grunts make the caller easy to locate, and may have evolved for that function. The roar elements, containing the most energy, would have the potential for telling the most about the animal--its age, condition, size, and the like.
.....that I went to the Serengeti as a graduate student to find out why lions put so much energy into roaring. And energy they do put in! Norm could shake our cars from 30 yards away, be heard five miles away, and do this over and over again throughout the night."
http://nationalzoo.si.edu/Publications/ ... nsroar.cfmYaaaawn... time for a nap, I've put myself to sleep.
AC Waveform
In AC, or alternating current, electricity travels in a rising and falling pattern called a "sinusoidal" waveform. The term "sinusoidal" means that the waveform takes the shape of the sine function in Trigonometry, which looks like a sideways "S." The AC waveform ascends to a positive peak and descends to a lower peak, repeatedly. It takes time for the electricity to "peak," and that is why the waveform gets a smooth, rounded shape. For example, household electricity travels in a sinusoidal waveform with peaks of +120V and -120V.
DC Waveform
In DC, or direct current, electricity is naturally at flat level and does not alternate between positive and negative peaks. DC electricity is used in digital electronics, and sometimes artificial waveforms are created. When that occurs, the waveform behaves like the AC, sinusoidal wave. The difference is that the digital waveform has flat levels instead of rounded peaks, and it alternates between +5V and 0V. The DC, digital waveform takes on a "square" appearance and is often called a square wave.
Wave Cycle
A waveform of AC or DC electricity is comprised of a repeated string of positive/high and negative/low peaks. A single peak-to-peak alternation is called a wave period or a wave cycle. A wave cycle can be observed and measured on a laboratory tool called an oscilloscope. The amount of time that it takes one wave cycle to occur indicates the frequency of the wave.
Hertz and Frequency
Hertz is the number of waveform cycles per second. For example, household electricity travels at a frequency of 60 Hz. This means that 60 cycles of +120 to -120V alternations are traveling through household wires every second. Hertz is the standard unit that is used to measure frequency in all scientific disciplines.
120 Hz Vs. 240 Hz
To demonstrate the concept, a 120 Hz LCD television has a screen that "reacts" to incoming video data at a speed of 120 times-per-second. This indicates the quality and clarity of the picture. A 240 Hz television has a screen that reacts 240 times-per-second to incoming video data. Because 240 Hz is faster than 120 Hz, the 240 Hz television will produce a clearer picture and will be able to react to a larger amount of incoming data, such as the data in a high-definition signal.
Ya gotta get the Visual Bias or you will fall asleep every time.
iON
Login
FAQ
Search
