What is the difference between digital and analog audio?


What is the difference between digital and analog audio?

In: Technology

Analog audio is a continous wave, digital it’s like taking little pictures of the wave, that make it discrete. But there is too much pictures so in most cases you can barely notice the difference.

Analogue audio is stored in an analogue (continuous) medium such as vinyl or magnetic tape (audio cassette). Digital is stored in a discontinuous medium such as a CD or MP3.

Sound is a wave, so audio information just describes the shape of the wave. On vinyl there is a wavy groove which has that shape, on cassette there is a varying magnetisation of the tape which also has the shape.

~~On a CD the “height” of the wave at each moment in time is assigned a value from 0 to 255~~ *~~65535~~*~~. Then at the next timestep it has another value. So the true wave shape is approximated by a sort of stepped shape. See a comparison~~ [~~here~~](https://www.google.com/url?sa=i&url=https%3A%2F%2Fbeatlabacademy.com%2Funit%2Fmsd03-digital-analog-synthesizers%2Fasset-5-digitalanalog-waveform%2F&psig=AOvVaw3zWKdCV1GJ55rpplieYP3v&ust=1615291906233000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCNj6-LjVoO8CFQAAAAAdAAAAABAD)~~.~~

*A digital signal on a CD stores the wave form as a series of values at moments in time, with those moments very close together. Think of a series of dots where if you squint you see the original curve. There are 65536 possible values, stored every 1/44100 seconds, which is all you need to replicate the original sound when you play it back.*

So long as there are enough values ~~and short enough timesteps~~ the digital shape is a close enough approximation to the true shape that no human can hear the difference. MP3 and other digital formats go further and compress the audio, so they sort of describe the shape rather than simply approximating it as outlined above. This can lead to distortions that humans can hear (or claim to).

You might think that analogue is therefore ‘perfect’ in a way that digital cannot be. This is sort of true, but any real analogue medium will have physical limitations which add their own distortions to the sound, potentially to a greater extent than good digital audio.

*Edit to add: yes I am aware that a digital signal perfectly replicates the waveform up to the desired frequency, thanks for all the reminders.*

*Edit 2: alright alright I get it. People have strong feelings about this analogy.*

*Edit 3: actually scrap that I stand by my statement that a digital audio signal is an approximation of the original. Sound is not band limited, and does not have finite bit depth.*

Analog is wavy air, and can be stored as wavy grooves. Digital is 1s and 0s. When you want to listen to digital audio, it gets turned into wavy air again first so you can hear it.

I guess you mean analog and digital recording of audio.

Sound is vibration of air (or any medium it travels through). Its properties are frequency (how many oscilations it makes in a second, i.e. how high the tone is) and amplitude (how ‘big’ are those oscilations, i.e. how loud it is).

So, how to record that? In essence, there are three ways: vinyl records, magnetic tapes and digital.

Vinyl is the simplest one. Imagine a big membrane that is in the way of those vibration. From the air, the vibrating transfers to the membrane. Now connect a sharp needle to it so it vibrates too. And while vibrating, that needle leaves the marks on a rotating dics. Then you can go reverse and the needle follows the grooves on the record, vibrate, transfer vibrations to the membrane and then to the air so we hear the recorded sound. Sure, this is oversimplified but it shows the important part.

Tapes work similarly, but the membrane is not connected to a needle but to an electromagnet. Magnets and elecrticity have a love relationship. When a magnet moves near the wire coil it creates electricity in in. And vice versa, if there is electricity in a coil, the magnet will move. So, as the magnet vibrates it creates a small amount of electric current that magnetizes the small particles of iron oxide on a moving tape. What was a wiggly scratch on a vinyl is now a series of variating little magnets of different strengths. You play the tape by reverting the process: tiny magnets on tape create the electricity in the electromagnet in the tape-player head, which moves the magnet connected to the membrane which creates the sound.

Both these systems transfer physical properties of sound into some other physical properties – depth and width of scratch mark on the vinyl or strength of magnets on tape.

Now the digital recording… which also goes from the membrane and into electromagnet to transform the vibration into electric current but then that current get measured and stored as a number.

As the sound is vibration that changes many times a second (it goes from 16 to 20000 oscilations per second) it has to do quite a lot of these measurements and store a number for each one. For CD it is 44.1 thousand per second, film standard is 48000 and, more often than not, initial recording in profesional environment is 96000 times per second.

Difference between this and the previous two ways is that now we don’t have one physical property transfered into other but into a series of descrete numbers somewhere in memory of the computer.

To store them permanently, you can enrave them into silver foil (CDs and DVDs) or use magnetic disks (hard drives).

Magnetic disks use the same mechanism as the audio tapes but they don’t record the vibrations directly but the numbers created according to those vibrations. So what’s the benefit?

(edited this paragraph as it was badly formulated) Magnetic tapes and disks are losing a tiny portion of quality with every reading/listening. Here is the important difference. If you copy analog data from the tape, there will be more and more shhhhhh noise introduced in every new generation of a copy as the electricity makes noise. But the copying of a digital recording is immune to that as each new reading and copying gives the same series of numbers as the original even if the recording is faded or partly damaged. That is because even as the magnetic material wears off, reading of the numbers is the same and when you deal with numbers you have safety mechanisms to check if your reading is ok or even to recalculate a part that is missing (see checksums for more info on this). But eventually the hard disk will fail.

OK, here’s a really ELI5:

Sound travels in waves. Tie a jump rope to a fence and wave it up and down; the shape of the rope will resemble a sound wave. Now imagine you could freeze time, and you wanted to build a copy of the rope’s shape, but you only had bricks.

So, you take your bricks, and start to stack them up under the rope. Some times you’ll only need a couple of bricks; sometimes you may need to pile them up 10 or 12 high to touch the rope. After a while, if you step back a bit from your work, you can see how the piles of bricks look *very much*, but not exactly, the shape of the rope.

The rope is the “analog” wave form, while the bricks are the “digital representation”. The analog wave is *continuous* – the rope’s height above the ground can have any value between, say 2 inches and 4 feet. The digital representation is *discrete* – it can only be 1, 2, 3, 4, etc. number of bricks. It can’t be 3.867 bricks.

Analog systems capture the continuous wave. The groove in a record – do 5 year olds even know what those are anymore? – is a long continuous wiggle that copies the original sound wave. This is actually fairly simple to do – the first records were made of wax, with the platter rotating while a needle, driven by a microphone, made the groove on the surface. This is an analog to analog process.

Digital systems try to recreate the original wave by using standard sized pieces to fill in the space beneath the wave, just as we did with the rope. But how wide, and how tall, should each of these pieces be?

This is beyond ELI5, but there was a smart guy named Nyquist who figured out that to completely capture all the information in the original wave, it needs to be sampled at twice its highest frequency. This tells us how “wide” the bricks need to be. For example, if the highest frequency in the wave was 4000 cycles per second, then we would need 8000 samples, so our ‘bricks’ have to be 1/8000 of a second wide.

The height of the bricks are is a function of how many digital bits in each brick. If you use 8 bits, you can get 2^8 = 256 levels. If you use 16, you get 2^16 = 65,336 levels. If you use more bits, it makes the bricks less high, so you can squeeze the brick piles closer to the actual wave, and so sound more like the original.

Note the digital process requires an analog-to-digital conversion at the input, and then a digital-to-~~audio~~analog conversion at the output. There are some – Neil Young comes to mind – who believe that this distorts and ruins the original recording; others don’t notice it.

finally, and this is way beyond ELI5, digital techniques like Adaptive-predictive Pulse Code Modulation (ADPCM), use clever math and engineering tricks to get the sound even closer to the original, while using less bandwidth.

EDIT: Thanks for all the kind comments and awards. Thanks also to those who corrected the minor errors, and expanded on some of the stuff I left out.

EDIT EDIT: To all the longitudinal wave fans. yes, you’re right. So am I. A sound wave can be represented as a two-dimensional signal on an oscilloscope, and it was that representation I was referring to. I elided the silly scope reference because it’s ELI5.

The most essential difference is in the ability to copy it. Analog is like copying a drawn picture, at each copy it deteriorates a bit, but you can get (in theory) the most minuscule details in there. Digital is like copying a written text, an E stays an E, or it changes in something entirely different (like an F). You can keep making a copy of the written text with no loss of information, unlike a picture.

Analog stores the waves themselves, and converts waves on a vinyl record into waves of voltage/current to your speaker.

Digital stores waves as numbers (bits), where the height of the highest point on the highest wave is the biggest number, and the the total amount of numbers per second represents the highest frequency you record.

Then processors read the bits and convert it to voltage/current outputs to your speaker.

So the difference is in how you store it, as you get the same result from both (there are slight differences, and professionals might have to look at their requirements in detail)

Here is electronic music pioneer Wendy Carlos on the different between digital and analog audio:

” Digital, of course, is essentially computer data which accurately describes an audio signal. It’s easily manipulated and can be copied exactly — all those ones and zeros, you know. Analog is how we usually describe sound waves, a continuous change of pressure or an electrical signal, what a microphone produces, what we used to record on tape. It’s a much riskier way to handle audio, but historically was the method we first discovered.

Between the two, don’t look for deeper meaning or arbitrary differences. There is a cult of near-religious dogma that proclaims analog sound on LPs (“vinyl”) to be perfection (what a hoot that is for those of us who used to cut LPs for a living!). They think you have to use special wires and elaborate techniques they don’t even understand, and they claim that digital is in cahoots with Lucifer. It’s kind of pathetic, based on ignorance and flamboyant cheek. The simple answer for synthesizers or reproduction is: To the listener, it shouldn’t matter at all, as long as it sounds fine. If you’re a performer, it shouldn’t matter at all. If you have a very advanced analog synthesizer and then you have another that is all digital–and you get a lot out of both–fine, use them.

On the other hand, digital can, in principle, let you be more precise, with finer finesse and control. Analog runs out at five significant digits of accuracy (it doesn’t have infinite resolution), something like that, and there’s tape hiss to contend with. If you want to put the money and time into it, you can obsess with digital until you’re dead. It’s a potential that hasn’t often been tapped, but usually you reach a practical limit, there’s life for you. Microtonal tunings are a breeze with digital synthesizers, but very hard to do with analog.”

From: [http://www.wendycarlos.com/intvw01.html](http://www.wendycarlos.com/intvw01.html)

Analog = Recorded by Physics (Analagous)

– Scratching sound waves into a record
– Recording sound impact on magnetic tape
– Real film photographs
– Can be done without electricity
– The recording happens by physics directly effecting a recording medium. The playback happens be the recorded medium effecting some kind of amplified replay device like a speaker. The record is an atomic level, mimicking shadow of a real event.

Digital = A recreation of physics through instructions. Usually numbers. (digits)

– CD, Youtube, MP3 audio
– Digital photos. Not vectors.
– Requires some kind of processor. Usually a micro chip. But can be other mechanics.
– Player pianos that use paper rolls or music boxes that use a music spindle.
– There are 2 processes: encoding and decoding. Encoding takes real world physics and records it to numbers. Decoding “plays back” the numbers to create physics.

There are some incorrect explanations in the comments here. [A digital signal has the same resolution as the analog to digital converter originally encodes](https://youtu.be/pWjdWCePgvA?t=635). There is no data loss due to “stepping” or “discreteness” of the digital signal.

That video is somewhat technical but has an accurate explanation of the differences- and surprising similarities- between digital and analog signals.

Analog is wiggles. Digital is numbers that say how big and how fast to make the wiggles.

Speakers wiggle the air which wiggles your eardrums. So either way, the end result is wiggles.

Digital is nice because if you see a messed up “5” it can be easy to see it was supposed to be a “5” because you know what 5s are supposed to look like. (Real digital signals use binary, but the concept is the same.)

But if a wiggle gets messed up, it just looks like another wiggle. So you can’t fix errors as easily with analog. This means analog is more susceptible to noise.

Digital requires conversion back to analog to make the wiggles for the speakers. Having to convert back and forth is the downside with digital. The faster the wiggle changes, the more numbers per second the electronics have to convert. But modern tech has no problem doing this with wiggles that only change as fast as audio does.

Drawing a wave using Lego vs Pen. You can get more accurate interpretation of the wave using regular lego vs duplo (frequency/sampling)

Analog looks like the thing it represents. In this case wavy air is replicated by wavy grooves on vinyl, or wavy magnetism on a tape.

Digital turns things into numbers. In this case the wavy air is measured at various points and the numbers stored in binary reflective areas on a CD or electrons in flash storage.

Audio engineer, here. Something I can finally contribute to on this sub! [This article](https://www.klipsch.com/blog/digital-vs-analog-audio) does a really good job describing the basic process in a straightforward way.

“No matter which recording process is used, analog or digital, both are created by a microphone turning air pressure (sound) into an electrical analog signal. An analog recording is made by then imprinting that signal directly onto the master tape (via magnetization) or master record (via grooves) . . . Digital recordings take that analog signal and convert it into a digital representation of the sound, which is essentially a series of numbers for digital software to interpret.”

**Where an analog recording is similar to the fluency of film, a digital recording is stop motion photography.** Analog audio is an exact representation of the sound, whereas digital audio captures bits and pieces of the signal in ones and zeros (binary). This makes it seem like digital audio is inferior from a sonic standpoint (~~spoiler: it is~~), but digital audio has advanced to a point where the difference is negligible or even unnoticeable to the trained ear, with the exception of a few scenarios (namely heavy gain).

Edit: it is my **opinion** that analog audio/equipment sounds better than digital.

Analog is continuous and digital takes little samples. It’s like cooling at a picture vs a mosaic. The higher the sample rate of the song the smaller prices you are using for the mosaic.

Think about the difference between a real drawing on paper versus a pixelated image on a computer. The former is an analog image and the latter is digital. As you zoom in, you see ever greater detail on the real drawing, though eventually it gets kind of blurry. With the computer image, the pixels just get bigger. There’s a fixed amount of information in there and when you look close, you can see that.

It’s the exact same thing with audio. An analog audio signal is like the drawing where it is made out of something physical (like a voltage level), where the digital audio signal is just a series of integers.

The easiest way to visualize the difference is to ask this question;
What’s more accurate, a digital or analog (with hands) clock?

The digital clock is only as accurate as how many decimal places are represented. Maybe to the hundredth of a second on a fancy watch.

The mechanical (or analog) clock has a second hand which is continuous, technically if you blew up the clock face big enough, there’s no fraction of a second the second hand is not passing and therefore infinitely more accurate.

Digital vs analog audio is the same concept, there is nothing lost with the groove of a record while a tape or digital recording is limited to how many samples the medium allows.

I think it’s useful to understand the context of why you are asking, as there’s something that I think the other answers, which are technically correct, miss. The sound you HEAR is a waveform, always. The device producing the sound waves is “Analog” depending on your specific definition of the word and the context.

Most of the time this stems from some argument or need to figure which is “best” digital or Analog.

If we accept that sound waves can be represented by a 2d graph that plots the sound pressure exerted on your eardrum, this is an anlog of that sound wave. If we are talking recording formats, the term Analog has a more literal meaning as well especially in the bygone age of physical media.

A vinyl record, like an LP, is a literal, physical analog of the original sound wave. In the groove there are tiny peaks and troughs that that match what the sound wave looks like on that 2d graph of the pressure exerted on your ear drum. It’s reproduced by a needle tracing over the physical groove. An amplifier takes the signal from the needle and increases the sound pressure, amplifying the signal. It’s possible to do this on purely mechanical level, I.E gramophones, or using electricity. In an electrical system of amplification, the needle is connected to a device that creates a very small voltage when you move it up and down. A speaker that you hear sound from typically requires a great deal more voltage than the needle devices generates, so the amplifiers job in this case is to increase the voltage of the signal from the needle. A speaker is usually considered “Analog because of the kind of device it is. It is an arrangement of electromagnets that moves the core based on the input voltage. The cone of the speaker is attached to the core of the magnet and produces a sound wave by the cone moving air. The input signal is a constantly variable electrical signal that is faithfully and directly reproduced by the movement of the core. This wave is always sinusoidal in nature.

What you hear from the speaker is a sound wave that closely resembles the wave that the records physical “Analog” was originated from. In the case of an electrical system like I just described, if you measured the voltage over time at the needle using an oscilloscope you’d see a weak electrical signal, but it would be very similar to the peaks and troughs as the original record. If you then measured the same voltage over time at speaker, it’s again a very similar wave as the needle one, and the record one, u this time with a much higher voltage.

All sounds simple right? The reason I said SIMILAR wave and not SAME wave is that at each point in the process, noise is introduced. When the record was made, some noise is inherent in the process of doing that. When the needle devices changes the up down movement to voltage there is noise induced into the signal. When the amplifier takes the sound and increases the voltage, more noise is introduced.

I’m going to skip over tapes a medium, but the brief story there is that a tape is an analogue of an original wave that uses magnetisim rather than a physical representation as found in a vinyl record.

So then along comes “digital” processing. Digital equipment doesn’t deal with variable state. This is because it’s what is known as solid state. Different voltages mean very little to solid state devices. It knows only ON or OFF Not going into that here, but that’s where this term come from. In operation, you know the device is either on or off. Speakers are really the opposite of “solid state”, in operation they might be any almost infinitely variable. They need a voltage that is constantly variable, to produce a reproduction of the original recording.

If you store something digitally, at a fundamental level it is all just 1 or 0 in terms of value. The difficulty is, if you want to store a signal that is a constantly variable wave and then reproduce it on a speaker that needs a sinusoidal wave to produce sound, with devices that only know 1 and 0.

Well, let’s deal with storing the wave first. A microphone is basically like the needle on the record but in reverse. It’s a diaphragm attached to a similar device that when you speak to it, it creates voltage. This gives you the original, electrical Analog of the sound wave you want to store. What you do with your digital device is sample the voltage value of the wave produced by the microphone at specific, repeatable points in time. This is referred to as sampling rate. When you do this, you can imagine you don’t get a smooth sinusoidal curve, you actually get something resembling a load of steps, but if you trace a line through the centre of each step, you get something that approximates the original wave. The more samples you have, the smaller the steps are and the closer you’ll be to the original. The disadvantage of higher sampling rates is the much higher volume of numbers you need to store. You might be familiar with the files that store sound waves this way this way. They are called .WAV files, and they usually take up a lot of disc space on your devices. The devices that perform this conversion are called Analog to Digital converters.

Now you want to take your stored wave and play it back on your speakers. You need to take this wave approximation, that is basically what voltage the speaker needs to see at a specific point in time to produce the wave, and convert into the actual voltage the speakers need to work. This is done by a digital to analog converter.

In a typical digital music storage system, there’s usually an intermediate format, whare the wave is stored in a more compressed format, that introduces some loss of the original wave, with the benefit being that the file takes up less space on disc. This would be an MP3 file or similar. Now with streaming media what’s more important is how long that file takes to download to your device. No streaming service will give you WAV files directly, or even the more modern FLAC format which typically requires less space but doesn’t lose any of the wave. Your getting an AIFF, an MP3 or an OGG. The specifics of this are not so important, but the reality is that by converting from a WAV or FLAC some of the original wave is lost. This happens if you use a streaming service, or if you are dinosaur that still does MP3 files.

Let’s break down where some of the perceived issues occur in this set of transactions that make up a digital music system. There is both loss of original fidelity and noise in recording the sound picked up by the microphone when it is stored. When it it becomes compressed so that it can actually be used, either for streaming or stored on a device for playback, you lose yet more of the original wave. When you playback the file, there will be noise and sometimes further loss induced by the DAC.


If you been following along, you might be thinking, Analog is surely best then, less steps, closer to the original wave” this is not always true.

All Analog systems are susceptible to noise. This can have a serious impact on how good both the recording and the reproduction sound. Many billions have been spent trying too eliminate noise from these systems. It continues, as you must still have a microphone and a speaker to record and reproduce sound. (I’ll use reproduce, as you can to some extent eliminate the mic with modern music production where a great deal of the sounds you hear might be generated digitally.)

Digital systems don’t have an issue with noise. And the “loss” of fidelity induced by compression doesn’t really have an impact on how you experience the sound. All sound waves have elements that the ear can’t actually hear, but when you record the wave, it is stored anyway. Formats like MP3 and ogg are extremely good at getting rid of the bits of the wave that your ear wouldn’t be able to hear, even the system reproduced it effectively. There is also the advantage of digital signal processing, which is a process of eliminating noise, and dinner times effects that make the sound better using software. It’s only possible to do this in a digital system. It’s cheaper and more effective than what is possible in Analog systems.

It’s also worth considering transmission of an audio signal, A digital signal, whether it’s DAB radio transmission, Bluetooth or the HDMI signal from your games console won’t get noise induced into it. It’ll work, or it won’t. It won’t be better some days than others or deafen you cos you put your phone too close to it, or because you’ve got a bad connection or anything else. You don’t have to eliminate noise to repeat it between multiple locations. It can even self heal if something does go wrong during transmission using a technique known as error correction.

Because the difference isn’t really important. Both are a part of a system. What you hear is “Analog”. You can’t avoid that. These days it’s almost impossible to consume audio without some kind of digital technology, somewhere in the process, and that’s overall a good thing that has made the experience better, not worse.

Analog = seeing something in real life with your eyes. Fluid, uninterrupted view.

Digital = motion picture.

Digital, like a motion picture, takes a picture of what you’re hearing thousands of times every second and puts them all together in back to back. When you listen to the playback you can’t tell that these are static images, a moment in time, because there are so many being played back in quick succession.