Introduction about Audio

SoundThis beginner-level tutorial coverings the basic principle of audio production. It’s appropriate for anybody wanting to learn more astir doing work with sound, in either amateurish or professional person situations.

What is “Audio“?

Audio means “of sound” or “of the replication of sound”. Specifically, it adverts to the range of frequencies detectable by the human ear — approximately 20Hz to 20kHz. It’s not a badly idea to memorize those numbers — 20Hz is the lowest-pitched (bassiest) sound we can hear, 20kHz is the highest pitch we can hear.

Audio work affects the production, recording, manipulation and reproduction of sound waves. To understand audio you must have a grasp of two things:

1. Sound Waves: What they are, how they are produced and how we hear them.
2. Sound Equipment: What the different components are, what they do, how to choose the correct equipment and use it properly.

Fortunately it’s not particularly difficult. Audio theory is simpler than video theory and once you understand the basic path from the sound source through the sound equipment to the ear, it all starts to make sense.

Technical note: In physics, sound is a form of energy known as acoustical energy.
The Field of Audio Work

The field of audio is vast, with many areas of specialty. Hobbyists use audio for all sorts of things, and audio professionals can be found in a huge range of vocations. Some common areas of audio work include:

• Studio Sound Engineer
• Live Sound Engineer
• Music Producer
• Film/Television Sound Recordist
• Musician
• Disk Jockey
• Radio technician
• Field Sound Engineer
• Audio Editor
• Post-Production Audio Creator

Sound Engineer

In addition, many other professions require a level of audio proficiency. For example, video camera operators should know enough about audio to be able to record good quality sound with their pictures.

Speaking of video-making, it’s important to recognise the importance of audio in film and video. A common mistake amongst amateurs is to concentrate only on the vision and assume that as long as the microphone is working the audio will be fine. However, satisfactory audio requires skill and effort. Sound is critical to the flow of the programme — indeed in many situations high quality sound is more important than high quality video.

Most jobs in audio production require some sort of specialist skill set, whether it be micing up a drum kit or creating synthetic sound effects. Before you get too carried away with learning specific tasks, you should make sure you have a general grounding in the principles of sound. Once you have done this homework you will be well placed to begin specialising.

How Sound Waves Work

Before you learn how sound equipment works it’s very important to
understand how sound waves work. This knowledge will form the foundation
of everything you do in the field of audio.

Sound
waves can also be shown in a standard x vs y graph, as shown here. This
allows us to visualise and work with waves from a mathematical point of view.
The resulting curves are known as the "waveform" (i.e. the form of the wave.)

The wave shown here represents a constant tone at a set frequency. You will
have heard this noise being used as a test or identification signal. This "test
tone" creates a nice smooth wave which is ideal for technical purposes. Other
sounds create far more erratic waves.

Click here
to listen to this tone (22KB wav file)

Note that a waveform graph is two-dimensional but in the real world sound
waves are three-dimensional. The graph indicates a wave traveling along a path
from left to right, but real sound waves travel in an expanding sphere from the
source. However the 2-dimensional model works fairly well when thinking about
how sound travels from one place to another.

The next thing to consider is what the graph represents; that is, what it
means when the wave hits a high or low point. The following explanation is a
simplified way of looking at how sound waves work and how they are represented
as a waveform. Don’t take it too literally — treat it as a useful way to
visualise what’s going on.

In an electronic signal, high values represent high positive voltage. When
this signal is converted to a sound wave, you can think of high values as
representing areas of increased air pressure. When the waveform hits a high
point, this corresponds to molecules of air being packed together densely. When
the wave hits a low point the air molecules are spread more thinly.

In the diagram below, the black dots represent air molecules. As the
loudspeaker vibrates, it causes the surrounding molecules to vibrate in a
particular pattern represented by the waveform. The vibrating air then causes
the listener’s eardrum to vibrate in the same pattern. Viola — Sound!

Note that air molecules do not actually travel from the loudspeaker to the
ear (that would be wind). Each individual molecule only moves a small distance
as it vibrates, but it causes the adjacent molecules to vibrate in a rippling
effect all the way to the ear.

Now here’s the thing: All audio work is about manipulating sound
waves. The end result of your work is this series of high and low pressure
zones. That’s why it’s so important to understand how they work - they are the "material" of your art.

Source : www.MediaCollege.com