
Session 1: Today we’ll discuss a few principals of sound itself. Sound is made up of high and low pressure waves that travel through matter. We can perceive sound traveling through air at frequencies ranging from roughly 20Hz to 20KHz, and are able to record it using microphones and analog or digital recording media. The frequency (rate or speed) of sound is measured in Hertz (Hz) or cycles per second. One cycle of a waveform includes one peak (high pressure) and one trough (low pressure). The amplitude of these sound pressure levels (SPL) is measured in decibels (dB). Let’s listen to sine waves at various frequencies to get a better understanding of how frequency and amplitude work.


What’s the difference between analog and digital recording? Analog recording translates the sound waves into an electromagnetic signal which is then stored on magnetically sensitive tape. Alternatively the waves are physically carved into record grooves for vinyl production. Digital recording encodes sound samples at intervals in time into numerical data. The rate of these intervals is called the sampling rate and is indicated in KiloHertz. The faster the rate, the higher the recording quality. The sampling bit depth indicates the resolution of the sample, or how the amplitude of the sampled sound wave is divided. CDs use 16 bit resolution and a sampling rate of 44.1KHz. The information is then stored on some type of digital media such as a hard drive in a computer, a CD, or a DAT (Digital Audio Tape) cassette.
Question: when you hear music from headphones plugged into a mobile phone, iPod, or computer is what you’re hearing digital or analog sound?
Required Reading:
Édouard-Léon Scott de Martinville’s Phonautograph
Recording Technology History
Digital Audio Basics

Vi Hart video on sound:
Next class: Please bring a set of closed ear (circumaural) headphones for our first exercise. The headphones will be necessary during studio time and outside of class to edit and mix your projects throughout the semester. As of August, 2023 there are nearly 6400 products on Amazon under over the ear headphones. I tend to lean toward trusted brands such as Tascam, AKG, Beyerdynamic, Sennheiser, and Sony. The inexpensive set linked below will do well.
Suggested Circumaural Headphones:
Tascam TH02 Studio Headphones
Session 2: Today we will be gathering digital audio from an online source called Freesound, then using DSP to loop and manipulate a short segment of sound. Once we have downloaded the audio import into Adobe Audition where we will learn how to edit and process the sound. I will be demonstrating this process today.
Use Audition to edit a region or loop of audio that you want to work with. Make a copy of your region and apply pitch shifting and at least three more kinds of signal processing in order to come up with a new and completely different sounding loop. When you’re happy with the results bounce the audio to a new file and upload the unprocessed loop and the processed loop to Canvas (2 files). We will listen to the loops in class on so make sure you have finished your loops before Session 2, Week 2.
DSP or Digital Signal Processing is the manipulation digital audio within digital circuitry or software verses within an analog signal path. There are many different types of DSP. Each type is essentially a different algorithm with a set of user adjustable parameters used to manipulate digital audio. Some examples of DSP include level or volume adjustments, equalization or filtering, panning, looping, delay or echo, reverberation, time compression or expansion, and pitch shifting.
Exercise 1: “Looping Experiment”
Due: Session 2, Week 2 (5 points)
Description:
This assignment is an introduction to working with a DAW (Digital Audio Workstation) and discovering a few of the possibilities for manipulating sound with DSP (Digital Signal Processing). We will download audio from Freesound, import audio into Abode Audition, set markers for looping sound, trim the loop, and apply a minimum of three types of DSP including: pitch shifting, pitch bending, reverse, delay (echo), reverb, time stretching, time compression, phasing, chorus, equalization, and filtering. The length of your loop will be greater than one second and less than ten seconds. This exercise will be demonstrated in class.
Requirements:
1. Pick a sound of your choice from Freesound
2. Download the audio in WAV format at 44.1kHz/16bit or higher
3. Import the WAV file into Adobe Audition
4. Choose a segment of the audio between 1 and 10 seconds in length
5. Trim the audio to your selected range
6. Apply pitch shifting and a minimum of three other kinds of signal processing
7. Upload the processed loop and a “clean” version (no effects) to Canvas before class starts on Week 2, Session 2.
Points Breakdown:
2 points are awarded for selecting an interesting segment for looping
3 points are awarded for experimenting with signal processing
Adobe Audition Overview