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Difference Between Mono and Stereo Sound

Satyajeet Vispute Aug 24, 2020
Many of us must have seen the word 'stereo' printed over our headphones or speaker systems, without giving any thought as to what it means. Some of us might even have heard about a seemingly obsolete term - mono. What are they? In this story, we shall answer this question and also tell you which one is better through a monaural vs. stereo comparison.
Did You Know?
Stereo systems have what is known as a sweet spot located in between the two speakers. Audience within the sweet spot, are able to equally hear the output from both speakers, and thus, experience the best of the stereophonic sound.
Unfortunately, however, the sweet spot is limited to a fairly small area and the listeners outside it, only hear one or the other audio channel.

Ask your grandmother and she will probably tell you that music today lacks 'warmth'.
Probe her further, and she might even tell you tales of the good old days when she would bake apple pie in the kitchen, while dancing along to a Beatles number playing over the single speaker transistor. Music sounded good back then, she might say. But really, is the warmth all gone from the music of today?
Until the 1960s, mono (monophonic) sound was the dominant force. All music and other sounds thereof, used to be recorded and reproduced using this technology. With the advent of stereo (stereophonic) sound technology in the later years, mono got quickly and completely replaced, and is now limited to only low-cost and certain other specialized applications.
So, how is it that this stereo technology, allegedly lacking in warmth, was able to gain such a lot of popular acceptance. To find out, we will have to dig deeper and look at the working of both mono and stereo technologies.
What Does Mono and Stereo Mean 

Mono Sound 
Mono sound, also known as monophonic or monoaural sound, is the oldest and simplest method of recording and reproducing sound. In it, all the different audio signals are mixed together into a single audio channel, and hence, it gets the name mono.
Monophonic sound recordings are usually done using a single microphone but may include more than one speaker for sound reproduction. It is important to note here that although multiple speakers can be used at the output, all of them will reproduce the same sound as only a single channel is used for the recording.
Multichannel audio signals too can be mixed together into a single channel to get a mono output.

Monophonic systems can still have full audio bandwidth as well as high fidelity. These systems can record and reproduce an audio signal of very high quality and amplitude.
However, being single channel, the mono audio signal contains no level difference or changes in the arrival time or phase of the different sound frequencies. Because of this, mono sound systems are virtually unable to exactly replicate the aural sensation of depth and the three-dimensional perception of the real world.
One important characteristic of a monophonic system is that all the speakers output the same sound. In a well-designed mono system, the speakers are able to reproduce equal levels of sound. This can prove to be highly advantageous in certain special applications such as a public address (PA) systems, radio talk shows, etc.
Being cheaper to implement, monophonic technology is also widely used in single speaker applications such as telephones, cell phones, hearing aids, etc.

Stereo Sound 
Stereo sound is a relatively newer technology. Since its conception, it has taken over and replaced mono sound technology in most applications.
Stereophonic sound systems have two independent and distinct audio signal channels. Sound signals that are produced in these systems have a specific level and phase relationship between them. This allows stereo systems to more accurately simulate the actual recording environment in the reproduced sound.
Stereo recordings usually require more than one microphone. The positioning and placement of each of these microphones is extremely crucial. For optimum audio recording, the entire recording area needs to be covered and each and every source of sound needs to be given equal preference while being split into the two stereo channels.
This makes stereo recordings much more complex than mono recordings.

Similarly, the recorded stereo sound needs to be perfectly split into the two channels which are applied to the speakers at the output of stereo systems. This makes designing a good stereo output system a much more challenging task compared to a mono output system.
In a stereo system, each speaker apparently produces a different sound. The listener experiences this difference because, unlike mono systems, stereo systems output different audio channels via different speakers.
This allows for the creation of a virtual image of the original recording before the listener, which is beneficial when actual recordings of live performances are reproduced. The listener is able to visualize the positions of the different on-stage instruments, via the varying sounds coming from the stereo speakers, which enhances the listening experience.
While listening to prerecorded music as well, the user is able to get a greater depth perception in stereo systems.

Hence, these systems are exclusively used for both recording and playback of music and the audio in movies.
Mono Vs. Stereo Sound: Comparison

Mono - Mono' represents monoaural or monophonic sound.
Stereo - 'Stereo' represents stereophonic sound.
Mono - In it, audio signals are mixed together into a single channel.
Stereo - In it, audio signals are separated into two or more channels each of which is routed to a different speaker. This helps to better simulate the direction and depth perception.
Mono - Recording in mono is much easier and usually requires just one microphone.
Stereo - Stereophonic recordings require more than one microphone along with a great deal of expertise and skill especially while setting up the position of the microphones.
Mono - The designs of the instruments used both for recording as well as reproduction of monophonic sound are simple.
Stereo - Complex deigns are used for making the instruments required for recording and reproducing stereophonic sounds.
Mono - Building a monophonic sound system is much less expensive compared to stereophonic ones.
Stereo - The stereophonic sound systems are much more complex to design and can be expensive.
Mono - Mono technology is used for special applications such as PA systems, radio talk shows, telephones, mobile communication system, hearing aids, etc.
Stereo - Stereophonic sound technology is widely used in almost all entertainment related applications such as movies, TVs, music players, FM radios, etc.
Dual Mono vs. Stereo 
Unlike what many people believe, a dual mono system isn't the same as a stereo system. To understand the difference, let's take the example of a dual mono preamp. Through one of its channels, the user might introduce vocals, while through the other, a musical instrument might be run.
These two channels are completely independent and can have individual and mutually exclusive settings.

A stereo system, on the other hand, has two channels which aren't mutually exclusive. There is a distinct interrelation between them. For example, a stereophonic keyboard outputs two channels together as one stereo signal.
These two channels are processed and routed together as a single stereo signal, and the separate outputs from this system are individually applied to the different speakers.
Which is Better Mono or Stereo? 
So now that we are clear with the concepts of mono and stereo sound, let's get back to our original question―which one is better? Well really, the answer depends on a number of different factors.

In a mono vs. stereo recording competition, stereo would easily win if only the sound quality of the recording was in question.
Mono would win if cost-effectiveness of the system was the main factor being considered.

Similarly, while comparing mono vs stereo on headphones, stereo would be the winner for producing better audio quality, while mono would win if design simplicity of the system was concerned.

The choice of the better one will also depend on the specific application.
While stereo is the best choice for movies, music, and other forms of entertainment, mono is better for PA systems, cell phone speakers, etc.

Last but not the least, is individual preference. We all are inclined to always prefer experiencing something that is exactly similar to the original.
So if your grandmother loves listening to Beatles on mono, it is mostly because that was how she had first heard and experienced it.

Most systems today are stereo, and all the audio that we experience is in stereo right from the very start. Hence, it is almost inconceivable for most of us to switch back to mono.
Thus, mono and stereo are two important audio technologies, each having distinct applications in modern times. In most cases, stereo is quite clearly the better option and only in certain specific applications or when the cost and complexity of the system is a major factor, is mono preferable.