Note that MIDI operates at a BAUD rate of 31250, which is not one of the available choices in the Arduino Serial Monitor screen. So MIDI needs to be monitored with a special MIDI program.
Pocket MIDI is a MIDI monitoring tool for Windows and Mac. Connect your MIDI instrument to computer using a USB or USB/MIDI adapter and you can monitor MIDI messages to and from your instrument in real time. You can also send message from the application to your instrument. Pocket MIDI(for Windows/Mac) is freeware.
MidiView is a simple MIDI Monitor app, for Windows and Mac, that shows bi-directional MIDI packages that flow through your computer.
MIDI-OX is a Windows 32 bit program., the world's greatest all-purpose MIDI Utility!
Midi Monitoris a powerful tool to learn about Midi, to setup a Midi configuration and to exchange Midi System exclusive data. Midi channel messages real time monitoring.
MIDI Monitor (Mac only) is an app to display MIDI signals going in and out of your Mac. Musicians will find it handy for tracking down confusing MIDI problems, and programmers can use it to test MIDI drivers and applications. MIDI Monitor is free to download and use.
You can also use a virtual MIDI synthesiser installed on your computer for this project. For Windows, you can use VirtualMIDISynth at:https://coolsoft.altervista.org/en/virtualmidisynth
and for OS X SimpleSynth is probably best, at:https://notahat.com/simplesynth/
There are also many free MIDI Software Synthesisers available for PC/MAC/LINUX operating systems. Some are standalone but many use virtual interfaces.
There are multiple interface types that utilise the capabilities of either Digital Audio Workstations ( DAWs) which are the host platforms for plugins, or hardware. The most common interface types are:
Native PC (or Native Windows) - This means all interface types supported by Windows-based music platforms. This includes VST, RTAS and DX.
Native Mac - This covers all interface types supported by OSX-based music platforms - VST, AudioUnits and RTAS.
VST (Virtual Studio Technology) Introduced by Steinberg in 1996 in Cubase . It is the most known interface type for effects and instruments. As of today VST has evolved into its 3rd version and is commonly referred to as VST3. Also VSTi which stands for VST Instrument, which does not have any different technical requirements. VST is the most widely implemented standard in the industry.
AU (AudioUnits) Apples proprietary audio technology, part of the Core Audio provided by Mac X OS. It is part of the operating system so it provides low latency and system-level support for the interface. Most DAWs developed for the Macs support the AudioUnits interface due to its stability and system-level solutions (which also means faster processing). Ableton Live, Logic Pro, Cubase, Garage Band, Presonus Studio One and many others.
RTAS (Real-Time Audio Suite) Implemented in the ProTools series by Digidesign. Many plugin manufacturers develop RTAS versions of their plugins for the sake of compatibility with the ProTools series of DAWs. RTAS plugins can only be used in the ProTools system.