Before it is really possible to understand how speakers work, it is first necessary to understand how sound works.

How Sound Works

Humans are able to pick up sound due to a very thin piece of tissue in their ear that is commonly known as the eardrum. When the sound waves reach the eardrum, it vibrates and sends signals to the brain, from there the brain can then interpret the vibration as sound.

Although sound vibrations can travel through liquid and solid objects, it most often travels through air, which is how people experience sound from speakers. The way this works is that the sound waves vibrate air particles; at this point the air particles move particle disturbance through the air. The vibrating air particles send a fluctuating wave of pressure through the atmosphere until it reaches your eardrum. As the eardrum vibrates, it sends the sound signals to your brain.

How Speakers Work

When sound is recorded with a microphone or other recording device, is works much like the eardrum; it picks up the sound vibrations and converts them into electrical signals, and then either records it as data, or sends it to the speaker.

When electrical signals are sent to a speaker, what is happening is that the speaker is converting those electrical signals back into physical vibrations that will create sound waves. If the system is working correctly, the sound that comes out of the speakers will be nearly identical to the sound that went into the microphone or recording.

The speaker translates the electrical signal when it rapidly vibrates a flexible cone, and a signal is sent through the voice coil. To amplify the sound, it is constantly fluctuating the electrical current between a positive and negative charge. This moves the voice coil back and forth, which then vibrates the cone to recreate the sound waves that reach your ears.

Because the different speakers create difference sound frequencies, to recreate high quality sound it is necessary to have different types of speakers; this is why you will find that most good speakers have a woofer and a tweeter, all within the same compartment.

When looking for high quality speakers, it is important to pay attention to the design of the speaker enclosure. The design of the speaker enclosure will influence the final output; you will want an enclosure that provides good quality sound reproduction.

The most popular is the sealed enclosure, which is completely sealed and forces the sound out from the speakers into the room. The disadvantage of the sealed speaker enclosure is that it is not as efficient as some of the other designs, and requires a boost in the electrical signal to produce good sound, as there is no method of equalizing the air pressure.

Other speaker enclosures, such as the bass reflex enclosure, or the passive radiator enclosure are designed to overcome the air pressure by redirecting it out of a small port that is built into the speaker.

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How many people out there do you know that have really sweet audio set ups and a full array of cool gadgets, yet absolutely no idea how any of them work, what the meanings to all the confusing words are, etc. etc.?  Probably a lot.  That’s because the world of audio terminology is for pros—roadies, musicians, recording producers, system installers.  The average person doesn’t have the need to know exactly what the difference between mono and stereo is, as long as the tunes sound good coming out of the speakers.  Speaking of which, what’s the tiny speaker for, and what’s the big one for, you may ask?  Again, as long as they produce a clean, pleasant sound, most customers don’t really care.  For those who do, however, and want to reach a slightly more nuanced understanding of the audio terms that so constantly perplex them, let’s go over a few basics which pop up all the time, and therefore extend beyond the realm of the professionally trained and qualified.

A good start for anyone looking to polish their understanding of audio terminology is to take a high school physics class: that’s where almost all the basic ideas get explained.  Was that too long ago for you?  Oh well…perhaps some of the basic ideas lingered on in your mind.  We’ll focus more on the meanings, and not worry too much about getting into the nitty gritty details of how things work, and so on—let’s leave science lessons to the real teachers.

For starters, how about mono and stereo?  They sound like sidekicks on a cartoon show; so, what are we dealing with here.  Before the early 1950s, all recordings were in mono.  The meaning of mono—not just in audio terminology, but in its general etymological sense—is “single,” as in monotheistic (believing in only one god), monopoly (only one business dominating a market), or monogamy (only having one spouse).  Hence, when music was played in mono, all speakers to which it was routed were playing back the same channel, which results in a duller sound format.  The great innovation in music recording and playback (that came in the 1950s, as stated) was to introduce stereo playbacks, meaning that two separate channels, with similar but not identical sounds, are being routed to the amplifier or speakers.  The result of this innovation was the perception that the sounds were more dynamic, and much more enjoyable.  For example, on any given recording, certain instruments/noises may be more pronounced on one side compared to the other (what is referred to as panning left or right), and therefore when played back gives the listener the perception that certain sounds are originating from one side of the listening area, and other sounds from the other side.  Sounds confusing?  Just remember, stereo is about left and right—though today, with advances in digital music technology, multi-channel music is where the future lies.

Moving on from what’s being sent to the speakers to the speakers themselves: why do we have those dinky little one’s up top, and those bulky one’s down below?  And why do they seem to be playing the same music very differently?  That’s because they are!  A woofer, which would be the larger variety of speaker, is a low-frequency playing device, and gets all the bass tones of a song or voice; conversely, a tweeter, the little one, plays high-frequencies of a given song or sound.  What exactly are frequencies, you may be wondering?  All sound is made up of waves, and the frequency is the measure of how many cycles that wave completes in a second, and is measured in Hertz (Hz in its abbreviated form).  The lower frequencies produce low, bass sounds, whereas the higher frequencies produce crisp, shrill sounds.  A good audio set up includes both woofers and tweeters, because neither one of them is able to produce both ranges of frequencies (though they both play a certain amount of middle frequencies, though that’s not important).  Think about the difference between a stand-up bass and a ukulele: the noises they create are vastly different.  That’s because the technology needed to produce low frequency sounds and high frequency sounds is not one and the same.  It’s always obvious if somebody has got an audio configuration with only one of these two types of speakers, and not the other.  Only having tweeters will give you dry, piercing sounds (really annoying), and only having woofers will give you a muffled, creamy variety of the song (less annoying, but still annoying).  What’s important to know about them in the end?  Have both.

Or how about amplitude?  This word brings us back to our sound waves: think of the X an Y axis of a graph (X is the horizontal axis, Y the vertical axis).  If frequency represents a measure along the X axis, then amplitude represents a measure along the Y axis—how “tall” it is when observed on a graph.  Amplitude, therefore, is literally the volume of a sound.  Amplifiers, therefore, take quiet sounds and make them louder, by stretching the sound wave on its Y axis (messing with a sound wave’s X axis would change the pitch of a sound, say from a C to a D).  A lot less complicated than the other two sections.

Hopefully these explanations have helped the average music listener appreciate their audio set up just a little bit more, and understand the technology going in to reproducing all your favorite tunes.  Keep listening!

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