Despite a massive jump in almost every kind of technology and electronics system used today, the home audio speakers most people have are strikingly similar to the ones they had in the 1970s. The only major change in speakers has been their size: surround sound systems are much more compact now than they were in the twentieth century. However, as technological advances continue to change every aspect of our lives, speakers, too, are getting ready to evolve. The speakers of the future will take some of the best aspects of those speakers of the past and combine them with the latest in modern technology.
What can consumers expect from the speaker industry in the near and distant future? How can speakers really change all that much? These questions are valid and worth exploring. Indeed, by looking into the function of speakers and understanding just how they work, it is not too hard to draw a vision for the speakers of the future.
How Speakers Work
Speakers are essentially both the beginning and end of a good audio system. Regardless of the quality of the music, the storage device, and the amplifier, a bad speaker will make the whole package sound like alley cats in a bag. In other words, without good speakers, there is no good music. Therefore, learning the ins and outs of how speakers work is the first step to uncovering the future of speakers.
The Basics of Sound
To understand how speakers work, it is first necessary to understand the function of sound. In the human body, sound is received through the ears and, more specifically, through a very thin piece of skin inside the ear canal called the eardrum. Sound, which travels in waves, vibrates the eardrum which then sends neurological messages to the brain, which are interpreted as sound.
The waves of sound are literally created through movement. For example, when a basic instrument, such as a bell, is played, the physical vibration of the instrument causes particles in the air around it to move. That movement sets off the movement of other particles in a wave-like fashion, reverberating through the air until the force of the movement is no longer strong enough to be heard (felt) by the eardrum. This wave creates a rise and fall in pressure that then impacts the eardrum and creates what humans and other animals interpret as sound.
Different Sounds and How We Make Them
There are two ways in which sound is translated to human ears: sound wave frequency and air pressure level. The first, sound wave frequency, refers to the speed at which the pressure fluctuates. The faster the frequency, the higher the sound, in terms of pitch. On the flip side, air pressure level refers to the wave's amplitude or height. The higher the wave, the louder the sound.
Recording Sound: the Microphone
Understanding that sound is interpreted in terms of both wave frequency and air pressure level helps to explain how sound is recorded, using microphones. Microphones operate much like the human eardrum, vibrating with the waves of sound created by instruments or the human voice. By using an internal diaphragm, microphones take those vibrations and turn them into electrical pulses, which can then be transferred onto a tape, CD, or digital computer file. Basically, the microphone codes the sound waves into electrical pulses, then an amplifier projects those pulses into a speaker, which decodes them back into sound waves that are recreated as physical sound.
Speakers: Three Main Parts
As the last step in the translation of sound to electronic signal and back to sound again, several components are involved in recreating an original sound wave through speakers. The function of these parts is pretty basic, however, it is important to review each of them separately to gain a better understanding as to how they all work together.
The diaphragm is the main piece of a speaker that produces sound. Once an amplifier decodes the electronic signals of a CD or audio file, the signals are sent through a series of drivers to a speaker diaphragm, also known as a cone (in reference to its shape). Made of metal, paper, or plastic, the cone is connected directly to the voice coil and is responsible for creating the physical reverberations which reproduce sound in speakers.
The Voice Coil
As a basic electromagnet, the purpose of the voice coil is to polarise the electrical signal as it changes with the amplifier's interpretation of the music. In other words, the voice coil reads the electrical signals from the amplifier and changes its poles accordingly. These changes produce different waves of electromagnetic flow which interact with the magnets within the speaker unit and create the physical vibrations of sound through the diaphragm.
The final piece of the speaker is its magnets.Working in conjunction with the voice coil and its ever-changing polarity, the poles of the magnets within a speaker are constantly moving. And, as anyone who has played with the polarity of magnets knows, a change in charge can either attract objects, drawing them towards one another, or repel them, forcing them apart. Thus, the magnets and the voice coil together create the physical flow of sound which moves the diaphragm and creates music through speakers.
Part of the reason that speakers have not advanced much in the past has to do with the simple and highly effective way they work. By using magnets, a technology well used and thoroughly understood by mankind, there has been no need to advance their function, merely to change their size and appearance. Therefore, in the beginning of the twenty-first century, the most notable advances to speakers have centred on making them smaller and wireless. However, in the future, the very system of speakers may very well be in for a change.
Speakers Get Smaller and Lose the Wires
The most noticeable difference between the speakers of the twenty-first century and the speakers of the twentieth century can be found in two areas: their physical dimensions and their power source. Speakers, even the most powerful amongst them, have gotten smaller and smaller while still producing booming sound. In fact, most surround sound systems these days rely on back speakers that are not much bigger than a milk bottle to operate. Front speakers are tall and thin, rather than large blocks, and even woofers and subwoofers have slimmed down substantially from their iterations in the 1990s, when at-home surround sound really took hold.
In addition, the way in which speakers receive power and electrical signals has changed. Whereas the original home theatre speakers of the twentieth century required large wires that clogged up walls and floors, wireless speakers that run on battery power are the new norm of the twenty-first century. In addition, the proliferation of Bluetooth and WiFi systems to deliver electronic signals has allowed consumers the ability to send their music signals through the air.
Speakers No Longer Use Magnets
While the slimming down of speaker units and the elimination of wires is nothing new, additional plans are also in the works to completely change the function of speakers altogether. Rather than operate on the traditional electromagnet and fixed magnet system explained above, the speakers of the future may use an entirely new system of technology to recreate sound.
Though greatly similar to traditional speakers in that the movement of a diaphragm recreates sound, the big advancement in electrostatic speakers is the design of the diaphragm itself. In electrostatic speakers, rather than a cone shape, the diaphragm is a suspended piece of thin conductive material (such as metal) cast between two conductive plates called 'stators'. These stators operate in the same way as the electromagnetic voice coil, sending reverse electromagnetic signals to one another, causing the diaphragm to move. This larger diaphragm, unencumbered by the conical shape of a traditional set-up, is said to create an improved frequency range and less distortion in sounds. However, some argue that the bass sounds in electrostatic speakers are weak by comparison.
Distributed Mode Loudspeaker
Like the electrostatic speaker, the main change from the traditional speaker set-up to the distributed mode loudspeaker centres on the diaphragm. Whereas traditional diaphragms were made to remain rigid in their construction, distributed mode diaphragms are made to bend. As a result, electrical pulses create a bended wave sound. The biggest advantage to this type of speaker is that the flat, bendable diaphragm allows for a small, narrow speaker made to fit in some of the tightest places. However, like other alternative speakers, bass can suffer in a distributed mode speaker. This fact can be aided, however, by buying a larger casing, but that essentially negates this technology's major benefit.
By far the most advanced speaker technology, carbon nanotube speakers are extremely thin. Also, they use a technology for re-creating sound that is completely different to any other speaker system. This technology is known as thermoacoustics and is similar in principle to thunder.
Basically, these nanotubes are small, thin tubes which attach to one another to form a film. Electrodes are then placed at either end. Electric signals from an amplifier are sent through the film, causing the air surrounding it to get hotter or colder, according to the sound. This heating and cooling process creates the same pressure waves as physical movement through air (i.e., a diaphragm) and sound is the result. This technology is currently more popular in headphones than in speakers, but is being developed for speakers for larger systems.
Despite decades of the same old technology, the speakers of the future possess the very real possibility of becoming something great. There are ways to revise the old way of changing electronic signals into real sound other than the simple formula of cone plus voice coil plus magnets. However, to understand these changes in technology, one must first understand sound itself and how speakers re-create it.
Once that basic knowledge is established, the process of understanding the speakers of the future is as simple as reviewing the ways in which technology can change that standard set-up. Mainly, this can be accomplished through a change in the diaphragm itself, as well as looking into the elimination of magnetic sound reproduction in favour of a more advanced thermoacoustic development. Overall, the speakers of the future have a lot of new ground to cover and will offer consumers some exciting choices in the years ahead.