# 2014 Journal

## July 7, 2014 - Day 1 Recap

Class Introductions
Frequency and Amplitude
Demo - littleBits
littleBits makes an opensource library of electronic modules that snap together with tiny magnets for prototyping, learning, and fun.
During the demo, Joe introduced four different modules included in the Synth Kit: power supply, oscillator, speaker, and keyboard.
Check out some cool projects made with the littleBit Synth Kit on their website here.
Key Terms
Frequency: The number of occurrences of a repeating event per unit time. This property determines the pitch of a sound.
Electronic Oscillator: An electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave. Oscillators convert direct current (DC) from a power supply to an alternating current signal.
Demo - IPython Notebook
The IPython Notebook is a web-based interactive computational environment where you can combine code execution, text, mathematics, plots and rich media into a single document.
During the demo, Professor Shlomo imported various audio files and showed the visual differences in sound waves by plotting it on a graph.
Check out this tutorial to help you get started with IPython.
Demo - Pure Data
Pure Data (aka Pd) is an open source visual programming language. Pd enables musicians, visual artists, performers, researchers, and developers to create software graphically, without writing lines of code. Pd is used to process and generate sound, video, 2D/3D graphics, and interface sensors, input devices, and MIDI.
During the demo, Cheng-I opened up a simple patch to display the basic interface of Pd. He showed how to connect two objects, and create a sound using an oscillator and digital-to-analog converter.
Get started with Pd here.
Key Terms
Digital-to-Analog Converter: a function that converts digital data (usually binary) into an analog signal (current, voltage, or electric charge).

What is Music?
Is it noise, silence, an art form, enjoyable sounds, a form of expression, a form of communication, or organized sound?
Is it a combination of multiple things?
Diana Deutch's Speech to Song Illusion
Shepard-Risset Glissando
Demo - Ableton Live
Ableton Live is a software music sequencer and digital audio workstation.
During the demo, Professor Shlomo and Cheng-I introduced different views available on Ableton Live, and some simple features that can be used.
Check out tutorials here.
Waves
What is a wave?
Translation of energy without translation of matter.
Waves travel through many types of media, even a vacuum!
Sound waves or acoustic waves are waves of mechanical & potential energy through a material.
Demo - Metal Springs
During the demo, Joe and Cheng-I displayed the movement of waves through a metal spring. By hitting the spring vertically, Joe sent a transverse wave to the other end, and the wave was inverted and returned. By compressing a part of the spring, Professor Mauricio send a longitudinal wave through the spring. If one end is left unfixed, the wave is returned without being inverted.
Key Terms
Transverse Waves: The local movements are perpendicular to the propagation (AKA shear waves).
Longitudinal Waves: The local movements are parallel to the propagation (AKA compression waves).
Demo - Guitar String under Strobe Light
During the demo, Joe and Professor Mauricio used a strobe light to make standing waves on a guitar string more apparent to the human eyes. A strobe light at the same frequency of the string vibration can make the string appear to be stationary, rather than moving.
Key Terms
Sinusoidal: A smooth repetitive oscillation. (Sine graph)
Standing Waves: are produced any time two sinusoidal waves of the same amplitude and frequency travel through a medium in opposite directions.
Harmonics
A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency, i.e. if the fundamental frequency is f, the harmonics have frequencies 2f, 3f, 4f, . . . etc.
Demo - Guitar String
During the demo, Joe introduced the harmonic series by having a student press down on the guitar string at a specific fret. The sound produced by this procedure is at a different pitch than the original sound the string creates.
Key Terms
Octave: the interval between one musical pitch and another with half or double its frequency.

## July 9, 2014 - Day 2 Recap

Split into Groups
Pd Extended
Audacity
Pure Data
Object, Message, Number Box, Comment, Wires, hot and cold inlets
Create a patch that converts BPM to intervals in milliseconds
Bang, toggle and metro - Fundamental objects
Trigger
Key Terms
Digital Signal Processor: A specialized micro-processor that is used to measure, filter, and/or compress continuous real world analog signals.
The Sine Wave
Formula
Frequency, amplitude, phase
Key Terms
Amplitude: The amplitude of a wave is measured as the height of the wave from the equilibrium point to the highest point of a crest, or from the equilibrium point to the lowest point of a trough. This property determines the loudness of a sound.
Phase: The initial angle of a sinusoidal function at its origin.
Little Bits
Connect oscillator to oscilloscope via breadboard and wires.
View sawtooth and square waves on the display.
Afterwards, students used the frequency on the oscilloscope to tune the littleBits oscillator to a specific pitch.
Key Terms
Sawtooth Waves: A non-sinusoidal wave that generally goes upward like a hill, and drops sharply. It can always go downwards and then rise up sharply.
Square Waves: a non-sinusoidal periodic waveform (which can be represented as an infinite summation of sinusoidal waves), in which the amplitude alternates at a steady frequency between fixed minimum and maximum values, with the same duration at minimum and maximum.
Jam Session
The class performed an improv jam session with a variety of instruments and a few brave vocalists!

## July 11, 2014 - Day 3 Recap

Interference of Waves
Interference occurs when several waves are added together provided that the phase differences between them remain constant over the observation time.
Key Terms
Constructive Interference: Occurs when the wave frequencies are the same and phase difference is a multiple of 2π.
Destructive Interference: Occurs when the wave frequencies are the same and phase difference is an odd multiple of π.
Pure Data
Beat frequency
Rhythm and pitch
Patches are located on the PureData page of the class wiki here.
Perception of Sound
Webern-Bach Ricercare
Karlheinz Stockhausen
Kontakte
Raymond Scott
Powerhouse
Lightworks
Audacity
Analyzing Waves
To analyze a sound file, select the file, click 'Analyze' on the menu, and select 'Plot Spectrum'.
You can also do this.
Removing Vocals
1) Split track into mono.
2) Select one track, and invert it.
3) Play both tracks together.
Key Terms
Timbre: The character or quality of a musical sound or voice as distinct from its pitch and intensity.
Spectrum: A condition that is not limited to a specific set of values but can vary infinitely within a continuum. A sound spectrum displays the different frequencies present in a sound.
Partials: Another term for periodic waves.
White Noise: In signal processing, white noise is a random signal with a constant power spectral density.
Vamp Plugins
Vamp is an audio processing plugin system for plugins that extract descriptive information from audio data — typically referred to as audio analysis plugins or audio feature extraction plugins.
Check out cool plugins for Audacity here.
Karaoke Session
After learning how to remove vocals in a song, the class began an impromptu karaoke session, complete with solos, duets, group performances, and an awesome rendition of “We’re All in This Together” from High School Musical.
You guys were amazing!!
Recording Session
For the COSMOS data analysis requirement, the class did three different types recordings:
“Ah” sound without pitch reminder.
“Ah” sound with pitch reminder.
Instrumental

## July 14, 2014 - Day 4 Recap

Circuits
Students learned how to utilize the multimeter in order to measure voltage from a power source and resistance.
Students created their first circuits consisting of resistors, capacitors, a button, and a light bulb.
They also connected the littleBit’s oscillator to a potentiometer through a breadboard.
Check out the Analog Signals and Circuits page to learn more.
Key Terms
Voltage: a measure of the (electric) potential energy across two points. Voltage is measured in Volts (V).
Current: a measure of the flow of (electric) charges (through a wire, device, surface, etc). Current is measured in Amperes (A), Amps for short.
Resistor: a passive two-terminal electrical component that implements electrical resistance as a circuit element. Resistors act to reduce current flow, and, at the same time, act to lower voltage levels within circuits.
Capacitor: a device that can store electric charge. Capacitance is measured in Farads (F).
Multimeter: an electronic measuring instrument that combines several measurement functions in one unit.
Potentiometer: a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment.
Raspberry Pi
Joe introduced the Raspberry Pi, a credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. By connecting it to the workstation computer via Wi-Fi, he was able to control the transducer’s vibrations.
Key Terms
Transducer: used to convert information from one form to another. For example, in music, microphones convert pressure waves into analog electrical signals, whereas speakers convert electrical signals into pressure waves.

## July 16, 2014 - Day 5 Recap

FIELD TRIP!
Media Arts Center San Diego
The Media Arts Center San Diego promotes access to film and video as tools for community self-expression and social change and supports the professional development of media artists.
Iacon Sound
Students were able to take a tour of an actual recording studio located in Golden Hills, just outside of downtown San Diego. There, everyone was greeted by co-owner Sulo King, who manages the business transactions of the studio alongside co-owner Frank Torres, the main engineer of the studio.
Check out their website here.

## July 18, 2014 - Day 6 Recap

Modulation
In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal (high frequency signal), with a modulating signal that typically contains information to be transmitted. In music, modulation is most commonly the act or process of changing from one key (tonic, or tonal center) to another.
Students observed the modulation of a wave through the littleBits’ envelope module, which contains knobs that control the attack and decay of a sound.
Students then recreated this envelope effect in a Pd patch.
Joe then presented a Pd patch that displayed the differences in sound that occur when using an oscillator versus a phasor to perform ring modulation.
Key Terms
Attack: the extent to which a note is hit.
Decay: the time within the full duration of the note that the sound is made.
Envelope: Sound synthesis technique that controls a sound's parameters at any point in its duration.
Phasor: an electronic sound processor used to filter a signal by creating a series of peaks and troughs in the frequency spectrum. The position of the peaks and troughs is typically modulated so that they vary over time, creating a sweeping effect.
Ring Modulation: a signal-processing function in electronics, an implementation of amplitude modulation or frequency mixing, performed by multiplying two signals, where one is typically a sine-wave or another simple waveform.
Music Theory
Harmonics
Rhythm to pitch via increased frequency.
Listening Examples
Links to the following can be found at Musical Ideas:
Renaissance Counterpoint
I am sitting in a room
Piano Phase
Ted Riley- In C
The Who - Baba O’Reily
Gagaku and Folk Music
Key Terms
Consonance: the combination of notes that are in harmony with each other due to the relationship between their frequencies.
Dissonance: combination of notes that sound harsh or unpleasant to most people.
Reverberation: created when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space – which could include furniture and people, and air.
Sequencer: a device or application software that can record, edit, or play back music, by handling note and performance information in several forms.

## July 21, 2014 - Day 7 Recap

Sequencer
The class continued with the event player Pd patch. (Can be found on the PureData page)
Added oscillator and v-line objects in order to change pitch and amplitude.
This quickly became messy, so to clean up the patch, students were introduced to sub patches, which can be created by naming an object “pd name_of_subpatch”.
Afterwards, everyone created their own melody by editing the seq.txt file that is used as an input.
Project Discussion
There were many great project ideas and instructors were able to give feedback.
Check out the Projects page for more ideas.

## July 23, 2014 - Day 8 Recap

Digital Signals
The class was introduced to sampling and aliasing.
They performed lab exercises in Audacity and Pd.
Check out the Digital Signals page to learn more.
Key Terms
Sampling: represent continuous waveforms as as series of numbers.
Aliasing: refers to the distortion or artifact that results when the signal reconstructed from samples is different from the original continuous signal.
Demos
The class displayed a few demos for some special visitors we had today:
Showing different modules on littleBits and how they work.
Building a sequencer in Pd.
Playing audio using motion patterns on Kinect.
Recording
Microphones
Joe instructed the students on how to properly hook up a microphone to a mic stand, and wrap up a XLR cord without creating tension that could potentially ruin the cord.
Types of Microphones
Dynamic: work via electromagnetic induction. They are robust, relatively inexpensive and resistant to moisture. This, coupled with their potentially high gain before feedback, makes them ideal for on-stage use.
Condenser: the most common types of microphones you'll find in studios. They have a much greater frequency response and transient response - which is the ability to reproduce the "speed" of an instrument or voice. They also generally have a louder output, but are much more sensitive to loud sounds.
M-Audio M-Track
USB Audio and MIDI Interface
Using their new microphone knowledge, students were able to record audio using Ableton.