A5

A5

1. Explain the historical background of the MIDI protocol. When was it established, and what type of “performance gesture” was it first designed to capture?

The MIDI protocol was established in 1984. It was first design to be a master keyboard that could communicate the sounds a many different keyboards in a a single board in order to making performing the music in a live setting less strenous.
2. Explain MIDI as an 8 bit system. How do Status Byte and Data Bytes differ as regards the MSB (most significant bit). What is the lowest possible status byte (expressed as base 10 number?) What is the highest possible data byte (expressed as a base 10 number?).

MIDI is an 8 bit system because their are eight binary choices available when creating yes and no switches. A data byte must have a 0 in its left most digit as opposed to a status byte which has a 1. This means that a note numbers max out at 127 because they are data bytes. The lowest statues byte would be 10000000 and the highest data byte would be 01111111.
3. Explain the configuration of a Note On message. What does the status byte represent, and how many data bytes are necessary for a complete Note On message?

A note on creates a status byte between 144 and 159, a data byte between 0 and 127 for a note and another data byte between 0 and 127 from the loudness. Therefore a note on must have two data bytes and one status byte. The status byte represents the channel used.
4. Similarly, explain the configuration of a Controller message (messages from sliders, joysticks, buttons, food pedals, wind controllers, etc.) What does the status byte represent, and how many data bytes are necessary for a complete Controller message.

A controller allows the user to modulate the sounds volume and pitch to create other effects for a performance. The status byte represents the channel used, which is between 176 and 191. There are two data bytes needed to complete a controller message.
5. Why is the status byte of a patch change message followed by only one data byte?

Their is only one data byte needed to tell the system which synth sound to patch with a new sound.
6. How are MIDI notes turned off? Is there a separate note off message, or is this managed in a different (and somewhat musically unintuitive!) way?

A MIDI note is turned off by changing the velocity to 0 on the data byte in the most convenient way.  their is another way by using two status byte but it is almost never used because of how much simpler a concept to just create a new note on message.
7. Explain how MIDI channels work in relationship to Note on and Controller messages.

The status bytes used by note on and controller message are similar but not quite the same values. The values of the channels are higher for controller channels as the range goes from 176-191.
8. How is a midi file structured in relationship to a millisecond time stamp?

A MIDI message travels a the speed of 1 message a millisecond therfore it is important to to relate each note on and off to a millisecond.
9. Imagine a drum pad trigger, where each pad triggers a different MIDI note. How would you set up a patch that would play different instruments on a drum kit? What would the velocities represent?

You would enter a statue byte that correlates to a patch channel and use different data bytes to put the patch drum ounds onto the MIDI. The velocites would represent the force applied to the pad triggers as you hit them.

MATHEMATICS OF SINE WAVE PAGE

10. The Mathematics of the Sine Wave. Read through this page and try to explain what this is saying in your own words. Those of you working regularly with mathematical concepts will likely find this relatively simple. If your major or area of study is not so mathematical, it has maybe been awhile since you’ve done trigonometry! Do your best to either explain what you read here, or write down questions for Tuesday’s class. You will not yet be able to run the Max demos, be we will look at these on Tuesday.

The key mathematics of a sin wave is the fact that its is a pattern of distplacements from zero that cycle between the value of pi to 0 to -pi to 0. The cycle is exponential sloped to make time go slower as the values approach pi and -pi. When this occurs at a high speed the maximun and minimun value can be clearly heard and distinguished to an overall sum frequency.

ADDITIVE SYNTHESIS/HARMONIC SERIES PAGE

11. Similarly, read through the page on Harmonics and Additive Synthesis. Explain this page as best you can in your own words.

Harmonics are created by adding together frequencies that create number ratios. A harmonic series is created by multiply a low frequency by 2 every time you increase an octave. You can create any wave shape sin waves in a harmonic series for a pitch. The pitches of two notes can also sound good together if the ratio is two, small whole numbers.
12. Conclude with describing the spectral content of a sine, triangle, square and sawtooth wave. How much energy (or amplitude) is present for each integer multiple of a fundamental tone, and how would you succinctly summarize that?

Their are four basic waveforms in computer synthesis and they are sin, triangle, sawtooth, and square waves.  A sin wave has a single fundamental frequency. A triangle wave had additional partials at odd frequencies  and the amplitude is equal to the inverse square of the harmonic number. A sawtooth wave has its amplitudes as the inverse of the harmonic number. A square wave had odd partials at the inverse of the harmonic number but not even partials.