Are audio sounds limited to radio waves?

Question

Is is possible to produce or hear messages or broadcast with different frequencies of micro, infared, gamma, ultraviolet, or x-rays? What would be an average range for those frequencies? And if not, what makes radio waves so special?

Answer 1

Yes, and the same way too. radio waves "carry" sound by modulating the amplitude of the wave by the sound wave (AM), or adding the sound's frequency to that of the radio wave (FM). AM can be achieved simply by coupling the microphone to the power supply of the source. FM is trickier, but can be done using an interferometer to optical, microwave, infrared, and ultraviolet and Mossbauer Doppler shifting/resonant absorption for gamma rays. In practice, though, encoding the information in digital form and digitally modulating laser light in a fiber optic proves the most practical alternative to radio and microwave transmission.

Answer 2

As a hobby, the fastest and cheapest way to bring you up to speed, is to find the nearest amateur radio club, and take a course leading towards a radio license. The club probably has a recommended textbook, or "study guide", which will explain all the basics, as well as local laws governing the hobby, so that neither you nor your listeners or fellow broadcasters experience unpleasant interference. In general, a nice clean sine wave can be created by energizing a "tank circuit" - an inductor and capacitor in parallel. The tank circuit will naturally resonate at one specific frequency, where f = 1 / ( 2 pi root (L * C) ) where f is in Hertz, L is in Henries, and C is in Farads. To keep the circuit oscillating, you'll need to create some feedback, with a simple transistor amplifier. If the amplifier design is not done properly, you'll end up with either a sine wave that decays to nothing, or a sine wave that grows until it distorts. The math here starts to get pretty complicated, pretty quick. Best to google "Hartley" or "Colpitts" oscillator schematics, and adjust the values as necessary. Once you've got a working oscillator, to make AM, you'll need to "mix" the oscillator (carrier) signal with your intelligence (audio) signal - one method is to amplify the oscillator with a variable gain amplifier, where the gain is controlled by the incoming audio. If you find the book "Electronic Principles" by Malvino, you'll find a mixer near the end of the book. You could also consider purchashing an AM transmitter kit... likely legal if only using a 9V battery, and 1 foot of antenna wire. Or, buy the book "ARRL Handbook for Radio Amateurs" - over a 1000 pages of circuits, theory, application, antennas, etc.

Answer 3

Radio Waves have a very long frequency and are therefore able to be broadcast at a much wider range and carry less direct energy. It would be possible to transmit information at other frequencies but this is very inefficient as they would need to be very energetic to carry the information without being disrupted. Furthermore, once you reach the high freq end of the spectrum, the danger of damaging radiation becomes an issue.

Answer 4

You could modulate any frequency to carry analogue audio data in theory, provided the frequency of the carrier wave was high enough.

Radio waves are useful for broadcast purposes because, being fairly long waves, they diffract around obstacles and it's possible to get a even signal most of the time.

Optical frequencies and other high frequencies would be unsuitable for this because they would require a line-of-sight to the antenna; it would be impossible to receive a signal indoors, for example, and car radios would be completely impractical.

Answer 5

So far everyone has missed the main point. Sound is the propagation of physical motion of particles in a medium like air, water, or steel. It can range from roughly 1Hz to 100kHz, with roughly 20Hz - 20kHz being the human audible range. All the rest are electromagnetic waves which don't need a medium for propagation.

Sound needs a medium, so a sound made on earth won't leave the earth and its atmosphere. It also dissipates quickly. We receive electromagnetic radiation of all types from distant galaxies, so their range is of the order of the scale of the universe.

Answer 6

You can make radio transmissions of any frequencies.
If you use x-rays a lot of people will get cancer. If you use infrared, you would not be able to pick up the signal through walls.
Radio waves can pass through most materials and they are not harmful.

Answer 7

I have no idea, but that is a really good question. I commend you for your curiosity. :P