All 8 MIDI Messages Explained

An explainer resource for you to return to again & again

Last week, I introduced you to the world of MIDI through a dialogue between two fictional characters: Roland Prophet and Toni Able.

Today, we’re getting to the heart of MIDI: MIDI Messages. Remember, MIDI is a communication protocol for sending and receiving musical data. This is why I dubbed MIDI the “Email of Musical Instruments”—to suggest that digital musical instruments, regardless of manufacturer, can communicate with each other.

This time around, we’ll dive into MIDI Messages, the raw building blocks of MIDI. Understanding the different message types is key to understanding MIDI itself. As you’ll see, MIDI Messages are closely linked to the history of synthesizers, and I’ll provide multiple examples to illustrate this. Without further ado, let’s dive back to the conversation.

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Toni: So… where were we again?

Roland: Well, last time we discussed MIDI, and I suggested that it is a communication protocol for sending and receiving messages—just like email. Now, to better understand MIDI itself, it’s worth spending some time exploring the actual bread and butter of MIDI: the messages themselves.

There are a total of eight types of MIDI Messages: Note On, Note Off, Aftertouch, Polyphonic Aftertouch, Pitch Bend, Control Change, Program Change, and System Messages.

Toni: Sounds like a lot of gobbledygook to me.

Roland: Right, yes, it’s maybe not the most intuitive naming system.

Toni: They’re not even musical. OK, maybe Note On/Off and Pitch Bend, but the others?

Roland: Yes, I get that. The names are perhaps not the most intuitive because they come from the world of computers and machines rather than from the domain of music. But you need to understand that MIDI is essentially a language that computers understand. So, the names reflect that.

Toni: OK, sure. So what about Note On and Note Off? What do they do?

Note On & Note Off

Roland: Note On and Note Off messages are the most elemental types of MIDI Messages. They instruct an instrument when to start or stop sounding a note. Importantly, this type of message does not encode duration—only when a note starts and ends. The duration results from the time that elapses between the Note On and Note Off Messages.

Another key piece of information encoded in a Note On/Off message is velocity. Velocity is a term that actually comes from physics, where it’s used to describe the speed of bodies in motion. In music-making, it refers to the speed with which a key is pressed, which translates to how loud or quiet a sound is.

A simple analogy might help explain how Note-On and Note-Off Messages work. Imagine you’re standing in your living room and turning on a light switch. That’s the “light-on” message: the living room lights up. A dimmer lets you determine the brightness of the room. That’s the “velocity” of the message, which is like the loudness of a sound. When you turn off the light switch, you’re sending a “light-off” message, extinguishing the light in the living room. The MIDI protocol works in exactly this way.

Toni: Cool, I get it. But there’s one thing I’ve noticed: when I set the velocity of a note, I can choose a value between 0 and 127. 127 seems like such a random number… what’s up with that?

Roland: Great question! 127 might seem random at first, but it makes sense once you understand how MIDI encodes values. MIDI is a computer language based on binary digits, or bits, where each bit can either be 0 or 1—like an on/off switch.

In MIDI, most data is encoded using 7 bits, which gives 2⁷ = 128 possible values. These values range from 0 to 127, with 0 typically representing silence or no velocity and 127 representing maximum loudness. This range was chosen to balance simplicity and efficiency while still offering enough resolution for expressive control.

MIDI messages are sent as bytes, which are groups of 8 bits. However, the first bit of a MIDI byte is reserved to identify the type of message—whether it’s a data byte or a status byte. This leaves 7 bits to encode the actual value, like velocity. That’s why MIDI values, including velocity, range from 0 to 127—it’s the largest range you can represent with 7 bits.

Toni: OK, I think I get it. So, what about the other message types? Which ones should I know about?

Aftertouch and Polyphonic Aftertouch

Roland: There’s another message type we should cover which might seem a bit unfamiliar but the mechanism is straightforward: Aftertouch. Remember velocity—that measure of how quickly you press down a key? Well, aftertouch describes what happens after the key has been pressed.

The function of aftertouch is that it acts a modulation source. That is, aftertouch itself doesn’t produce sound. Rather, its value can be mapped to any parameter on a synthesizer or keyboard: pitch, volume, filter cutoff, the LFO rate, glide, you name it.

Toni: Do you have an example?

Roland: Sure, let me whip up a quick chord progression. I’ll use Logic Pro’s RetroSynth, which lets you use aftertouch control the depth of the LFO modulation. The LFO can be mapped to the filter’s cutoff frequency. In this example, I’ve gradually increased the aftertouch parameter from 0 to 127 and back down again. You can hear the filter cutoff frequency is being opened and closed by an LFO to create a pronounced tremolo effect:

Toni: Cool! I’m intrigued. Tell me more. What was the first instrument to feature aftertouch?

Roland: Aftertouch was popularized in the late 1970s via a synthesizer called the Yamaha CS-80, introduced in 1977. While you may not have heard of this synthesizer before, it was the favorite of Greek film composer Vangelis and can be heard on many of his movie soundtracks, like Chariots of Fire (1981) and Blade Runner (1982).

Listen to the way Vangelis dynamically shapes the sounds over time. In the closing titles of Blade Runner you can hear a piercing lead sound in the far distance. Its brightness (filter cutoff) is modulated by Vangelis using the aftertouch capability of the CS-80:

The MIDI protocol has two forms of aftertouch: Channel Aftertouch, which applies one changing pressure value across all keys, and Polyphonic Aftertouch, which allows each key to be modulated independently. The CS-80 was special because it featured polyphonic aftertouch—the “deluxe” form of aftertouch, so to speak.

Toni: Got it. So what if I want to use aftertouch in my music projects? How would I go about doing that?

Roland: To use aftertouch in your setup, you’ll need two things: a compatible MIDI keyboard and a software instrument that supports aftertouch. Channel aftertouch is supported by many modern keyboards, such as the Arturia KeyLab 88 MkII or Novation Launchkey 88. Polyphonic aftertouch, which is rarer, can be found in high-end instruments like the ASM Hydrasynth Deluxe or Waldorf Iridium Keyboard.

In Ableton Live, instruments like Wavetable, Sampler, and Operator support polyphonic aftertouch, while most others handle channel aftertouch. In Logic Pro, stock instruments generally support channel aftertouch but lack native support for polyphonic aftertouch. Ultimately, aftertouch is just a neutral value ranging from 0 to 127 that can be used to modulate virtually any parameter.

Toni: Cool. So aftertouch itself doesn’t have a distinctive sound characteristic. Is that the case with other MIDI Messages as well?

Pitch Bend

Roland: Not really. Take Pitch Bend as an example. While aftertouch can be used to modulate pitch, pitch bend is quite a dramatic effect in and of itself. Pitch bend is designed for pronounced effects, raising or lowering the pitch in a smooth, continuous motion. Think of it like bending a guitar string, where the pitch moves fluidly up and down.

Toni: So how do I actually bend the pitch?

Roland: On a MIDI controller, pitch bend is typically controlled by a pitch wheel. Regular 7-bit MIDI controls can create a “stepped” effect that feels too coarse for smooth pitch modulation. To address this, pitch bend uses 14 bits, resulting in 16,384 possible values (!), which provides much finer control. In other words, pitch bend has a higher resolution than most other MIDI Messages.

The standard pitch bend range is ±2 semitones by default, but this can be customized in DAWs like Ableton Live or Logic Pro, where you can set different ranges for upward and downward pitch bends. For instance, you might set an upward bend to 2 semitones and a downward bend to 4 semitones. Here’s a simple pattern: first, you’ll hear it unbent, then bent up by 2 semitones, and finally bent down by 4 semitones.

Toni: Oh yeah, I can definitely hear it. That pitch bend down sounds like a record slowing down, though the tempo isn’t changing.

Roland: Exactly! In modern DAWs, you can even customize the pitch bend range for each virtual instrument. For example, in Logic Pro’s RetroSynth, the pitch-bend range can be set as wide as ±24 semitones (2 octaves). This flexibility makes pitch bend a powerful tool for creating dramatic and expressive pitch effects like this one:

Toni: Okay, that one’s a bit much to handle, honestly.

Roland: Fair enough! But you get the idea.

Toni: What was the first instrument to feature pitch bend?

Roland: Like aftertouch, we can point to a specific synthesizer that popularized the pitch bend effect: the Moog Minimoog Model D. It was the first commercially successful Moog synthesizer and it included a pitch wheel. To hear an early example of pitch bend, listen to Keith Emerson’s Minimoog solo on Emerson, Lake & Palmer’s track “Lucky Man.” You can hear it starting at 3:20:

Toni: Wow, that’s cool. I never thought about keyboard keys being bendable, like guitar strings. Okay, so what other MIDI messages should I know about?

Program Change

Roland: Program Change Messages are another classic MIDI feature. Their purpose is simple: to switch presets on a keyboard or synthesizer automatically, without requiring manual intervention.

The idea of programmable presets was first introduced with the Prophet-5 synthesizer in 1977, which allowed users to save and recall sounds digitally. Program Change messages were incorporated into the MIDI protocol to automate this process.

Toni: Ok, so how do I use program messages in my DAW?

In modern DAWs like Ableton Live and Logic Pro, Program Change messages have become largely obsolete. While DAWs still support Program Change messages for external MIDI instruments, they’re rarely used in contemporary production workflows, making them a relic of live performance setups and older synthesizer technologies. So you really don’t have to bother with them.

Instead of relying on them, producers like yourself would typically use a different method. You duplicate a software instrument and select a different preset for the new instance. This workflow is more flexible and better suited for DAWs.

Toni: Roger that. Won’t be needing those in the future. Are there any other messages I should know about?

Control Change (CC)

Roland: Alright, now let’s move on to one of the most versatile MIDI message types: Control Change Messages, or CC for short. These are like the Swiss Army knife of MIDI—they can do just about anything.

Toni: Anything?

Roland: Pretty much! Control Change Messages allow you to control various parameters in real-time, such as volume, pan, modulation, and effects. Each CC message has an associated number, ranging from 0 to 127, with specific numbers assigned to common functions. For example:

• CC1 is often assigned to modulation.

• CC7 controls volume.

• CC10 adjusts panning.

• CC64 is typically used for sustain pedal information.

Roland: Control Change messages are all about giving musicians precise, real-time control over expressive parameters like volume, pan, or modulation. But let’s save that for another conversation—it’s a big topic.

Toni: Oh, so that’s how my sustain pedal works! I always wondered how the software knew when I was pressing it down. Sure, let’s get back to it. Are there any other messages I should know about?

System Messages

Roland: There’s one last category: System Messages. These control aspects of your entire MIDI setup, like synchronization and device configuration. However, unless you’re managing a complex live rig or troubleshooting MIDI hardware, you’re unlikely to encounter them. In fact, some DAW manuals caution against using them unless you know what you’re doing.

Toni: Sounds mysterious—like a forbidden message.

Roland: Not really. They’re just more technical than creative. If you’re curious, I recommend watching this video by Simon Hutchinson—it dives into the details. But don’t expect it to be particularly useful for your day-to-day music production workflow.

Toni: Got it. To be honest, I feel like we’ve covered a lot of ground today already.

Roland: I’m glad to hear that! MIDI can seem a bit technical and overwhelming at first, but you’re getting the hang of it. Next time, we’ll take a deeper look at CC (Control Change) Messages. They’re incredibly versatile and open up a world of possibilities for expressive control and automation in your productions. Once we cover those, you’ll have the full picture of how MIDI works—and how to make it work for you.

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Don’t worry if you couldn’t remember all of the information above. You can return to it in the future. I’m intending these guides to be resources that can be returned to again and again.

If you want to go even deeper into MIDI Messages, I personally found this video by Simon Hutchinson really helpful, make sure to check it out.

I hope you will find this resource helpful in the future. If you’re enjoying this newsletter, feel free to share it with a producer-friend!