IMP Homework Episode 4: Dynamic range and the various ways to manipulate it.

Summary

This is episode four of my series on music production for my Coursera class Introduction to Music Production. I discuss the dynamic range of audio.

Transcript

To the reviewer

This one was fun. I got to talk more about my podcast, and I was able to focus on how I managed dynamics. I struggled again with time limitations; I had more content than time to cover it, so I limited my discussion to dynamics within my podcast and one creative use of compression in music production. There's so much to explore and so little time.

Key terms

Dynamic range: In a medium (i.e. something that can store or carry an audio signal), the range of amplitude from the noise floor to the maximum level; that is, the full range of representable amplitudes. In a recording, the range of amplitudes from the lowest to the higest sample.

Noise floor: The lowest measurable amplitude in a signal. It defines the lowest detectable sound in an audio signal.

Nominal level: The level a DAW or a system was designed to ideally work with.

Signal-to-noise ratio: The ratio of amplitude of the nominal signal level to the noise floor.

Maximum level: The highest signal amplitude in the system that can be produced without distortion.

Headroom: The distance between the nominal level and the maximum level.

Gain stage: A point in an audio signal path where the gain (level, amplitude) of the signal can be adjusted.

References

Robinson, George. The Ultimate Guide to Compression, First Edition, January 2013. Getthatprosound.com

Noise floor - Wikipedia
"The noise floor limits the smallest measurement that can be taken with certainty since any measured amplitude can on average be no less than the noise floor."

Nominal level - Wikipedia
"Nominal level is the operating level at which an electronic signal processing device is designed to operate."

Signal-to-noise ratio - Wikipedia

IMP Homework Episode 4: Dynamic range and the various ways to manipulate it.

IMP Homework Episode 3: Categories of plug-in insert effects in Digital Audio Workstations

Summary

This is episode three of my series on music production for my Coursera class Introduction to Music Production.

Transcript

To the reviewer

This week's assignment brought to me the challenge of brevity. I'm rather familiar with each of the three categories of effects, so I quickly brushed up on my definitions of each term and started writing. When done with the first draft, I had written almost 1200 words–much too long for a five-minute podcast. It was challenging to decide what to remove. thankfully, I have the key terms section of the show notes. I moved a number of topics there to shorten the podcast transcript.

Key terms

Dynamic effects are a category of insert sound effects that control the amplitude of a sound.

Compressor: reduces the dynamic range of a sound.

Limiter: enforce an upper limit on dynamic range by reducing or clipping the amplitude of any sound that goes over the threshold.

Expander: expands dynamic range of a sound.

Noise gate: reduces to zero the amplitude of sounds below a specified threshold. Gates can be used for other things too, like ducking one sound when another is heard.

Tremolo: In sound design, tremolo is the modulation of the amplitude of a sound, usually by an oscillator. If the frequency of this modulation goes up to audio rate, it becomes complex AM, which is a form of sound synthesis.

Delay effects are a category of insert sound effects that control the appearance of sound propagation by manipulating when a sound is heard.

Reverb: simulates a space, like a small room or a large cathedral.

Delay: simulates an echo.

Chorus: simulates multiple voices from one voice.

Phaser: mixes a a signal with a phase-shifted copy to create a special effect.

Flanger: mixes a signal with a slightly delayed copy to create a special effect.

Filter effects are a category of insert sound effects that affect a sound's timbre by manipulating its frequency spectrum.

High pass and low pass filter: cuts frequencies above or below a specified cutoff frequency.

Band pass filter: a combination of a high pass and a low pass filter, it cuts frequencies outside a single narrow band (i.e., both above and below) a specified frequency.

Notch filter: cuts a single narrow band around a specified frequency.

Parametric equalizer: raises or lowers levels of frequencies at a number of bands. It has a variable bandwidth of effect for each band, often referred to as the Q parameter. The shape of the filter at each band is often configurable.

Graphic equalizer: Similar to a parametric equalizer, it raises or lowers levels of frequencies at a number of bands. However, the bandwidth of the filter is not adjustable, and the shape of the filter is not configurable.

IMP Homework Episode 3: Categories of plug-in insert effects in Digital Audio Workstations

IMP Homework Episode 2: The Analog to Digital Conversion Process

Summary

This is episode two of my series on music production for my Coursera class Introduction to Music Production.

Transcript

To the reviewer

The content of last week's assignment was easy, as I know my audio equipment fairly well.

I thought this week's assignment was also going to be fairly straightforward, since I understand the basics of analog to digital and digital to analog converters. As I started to research this subject, I realized how wrong I was. I gradually be came overwhelmed by the subject, as I did not have the time this week to adequately research the subject and present a thorough summary of this surprisingly deep topic.

In lieu of the summary I'd like to present, I present you with this brief summary and a good list of references for further exploration.

Soundtrack for preparation of this assignment

All new music this week. Sound track for this assignment:

Reset - EP by Flying Lotus
Chaos Theory by Amon Tobin
Chaos Theory Remixed (The Soundtrack to Splinter Cell 3D by Amon Tobin
The Bible (The Official Score Soundtrack) by Lorne Balfe & Hans Zimmer
The Remixes by Pongá

Key terms

ADC: Analog to digital converter

analog to digital converter: converts analog audio signal to digital

sample rate: In an ADC, the frequency the analog signal is sampled

bit depth: In an ADC, the number of bits used to describe the amplitude of a sample

analog audio signal: sound represented as voltage in an electrical signal

digital audio signal: audio signal represented as binary data stream - a stream of 1s and 0s

References

Farnell, Andy. Designing Sound, MIT Press, 2010. See Chapter 7: Digital Signals.

Analog Devices. Data Conversion Handbook, Elsevier, 2005. The whole book is relevant, but the first chapter on data converter history is interesting, as is section 8.4 on digital audio.

Analog-to-digital converter, Wikipedia.

Episode 2: The Analog to Digital conversion process

Positive results on the first week's assignment

I got the results of my first assignment today. I got encouraging positive feedback, and helpful constructive criticism.

To my fellow students who gave me the excellent feedback: thank you!

I will endeavor to do even better on the next assignment, which will be posted Sunday. My chosen topic is the analog to digital conversion process.

I evaluated four assignments this week. One was a rather bizarre music video, one was a 500 MB video from a slow web server (but an interesting tutorial nonetheless), one was written in Spanish (Google Translate helped greatly), and one was written in both Spanish and English (the translation was excellent). All were very well done. It was a really fun experience evaluating all of them.

I look forward now to the next round!

IMP Homework Episode 1: Audio signal flow for the Late Night Geekery podcast

Summary

This is episode one of my series on music production for my Coursera class Introduction to Music Production.

Transcript

Late Night Geekery podcast audio signal flow

To the reviewer

At first I understood that the weekly assignment must have a video component. Since I am not well acquainted with video production, I am glad the options were clarified to include podcasting. Since I produce a weekly podcast, this is much more comfortable for me.

My chosen topic, my audio signal path, is a natural choice for me since I must understand and control it to produce my podcast quickly and with good quality. Since my signal path is somewhat complicated by the podcast recording over Skype and by the live stream, I felt a visual aid is required. I created a signal flow diagram as that visual aid. Podcast show notes (which you are reading) are a natural place to publish such visual aids.

I faced three challenges for this podcast in three steps I do not usually do for my weekly podcast.

First, I'm not used to preparing a transcript, which I wrote in advance. It wasn't that bad though, as I enjoy writing.

Second, I found the drafting of the diagram to be a challenge, since I only very rarely use Adobe Illustrator, and this is the first time I've used it (CS6 now) since CS4 a few years ago. I've never really used any other tool for creating diagrams.

Third, and most challenging, was recording the podcast alone, and from a script. I'm used to recording live, ad lib, with my friend Hobbes. I think it took me four takes to get a clean one.

I hope you like it and it exposes you to something new. I'd appreciate your feedback. Thanks for listening.

Soundtrack for preparation of this assignment

Language of The Ancients by S1gns Of L1fe
Black Boulder by Phon.o
Amber by Autechre
Strike 100 by various artists

Key Terms

transducer: converts sound waves to/from an electrical signal; e.g. a microphone, speaker, or headphones

analog audio signal: sound represented as voltage in an electrical signal

analog to digital converter: converts analog audio signal to digital

digital audio signal: audio signal represented as binary data stream - a stream of 1s and 0s

Digital to analog converter: converts digital audio signal to analog

Episode 1: Audio signal flow for the Late Night Geekery podcast