Audio Engineering Guide: Contents and Introduction

[More Parts and Sections to be added, so please check back frequently]

Part 1—Acoustics

Section 1 : Audio and Acoustic DNA—Audio and Acoustic Founders and Gurus

Section 2 : Fundamentals of Audio and Acoustics (coming soon)

Section 3: Psychoacoustics

Part 4--Electronic Audio Circuits and Equipment

Section 19: Power Supplies

Part 5—Recording and Playback

Section 27: Analog (vinyl) Disc Playback

Section 28: Magnetic Recording and Playback [part 1, part 2, part 3, part 4, part 5]

Part 6—Design Applications

Section 32: Grounding and Interfacing

Part 7—Measurements

Section 46: Test and Measurement

Introduction

We have seen a tremendous change in the field of sound and acoustics since the first edition of the Audio Engineering Guide came out. Digital is certainly finding its place in all forms of audio, however, does this mean analog circuitry will soon be a thing of the past? Analog systems will still be around for a long time. After all, sound is analog and the transfer of a sound wave to a microphone signal is analog and from the electronic signal to the sound wave produced by the loudspeaker is analog.

What is changing is our methods of producing, reproducing, and measuring it. New digital circuitry and test equipment has revolutionized the way we produce, reproduce and measure sound.

The Audio Engineering Guide discusses sound through seven sections, Acoustics, Electronic Components, Electro-Acoustic Devices, Audio Electronic Circuits and Equipment, Recording and Playback, Design Application, and Measurements.

When we listen to sound in different size rooms with different absorptions, reflections, and shape, we hear and feel the sound differently. The Audio Engineering Guide explains why this occurs and how to control it.

Rooms for speech are designed for intelligibility by controlling shape, reflections and absorption while rooms for music require very different characteristics as blend and reverberation time are more important than speech intelligibility. Multipurpose rooms must be designed to satisfy both speech and music, often by changing the RT60 time acoustically by use of reflecting/absorbing panels or by designing for speech and creating the impression of increased RT60 through ambisonics. Open plan rooms require absorbent ceilings and barriers and often noise masking. Studios and control rooms have a different set of requirements than any of the above.

There are many types of microphones. Each installation requires a knowledge of the type and placement of micro phones for sound reinforcement and recording. It is important to know microphone basics, how they work, the various pickup patterns, sensitivity and frequency response for proper installation.

To build, install, and test loudspeakers, we need to know the basics of loudspeaker design and the standard methods of making measurements. Complete systems can be purchased, however, it is imperative the designer understand each individual component and the interrelation between them to design and install custom systems.

With the advent of digital circuitry, sound system electronics is changing. Where once each analog stage decreased the SNR of the system and increased distortion, digital circuitry does not reduce the SNR or increase distortion in the normal way. Digital circuitry is not without its problems however. Sound is analog and to transfer it to a digital signal and change it back to an analog signal does cause distortions. To understand this, the Audio Engineering Guide delves into DSP technology, virtual systems, and digital interfacing and networking.

Analog disk and magnetic recording and playback have changed considerably in the past few years and are still used around the world. The CD has been in the United States since 1984. It is replacing records for music libraries because of its ability to almost instantly locate a spot in a 70+ minute disc. Because a disc can be recorded and re-recorded from almost any personal computer, disc jockeys and home audiophiles are producing their own CDs. Midi is an important part of the recording industry as a standardized digital communications language that allows multiple related devices to communicate with each other whether they be electronic instruments, controllers or computers.

The design of sound systems requires the knowledge of room acoustics, electroacoustic devices and electronic devices. Systems can be single source, multiple source, distributed, signal delayed, installed in good rooms, in bad rooms, in large rooms, or small rooms, all with their own particular design problems. Designing a system which should operate to our specs, but where we did not take into consideration the proper installation techniques such as grounding and common mode signal, can make a good installation poor and far from noise and trouble free. The Audio Engineering Guide covers these situations, proper installation techniques, and how to design for best speech intelligibility or music reproduction through standard methods and with computer programs.

The new integrated circuits, digital circuitry and computers have given us new sophisticated test gear unthought of a few years ago, allowing us to measure in real time, in a noisy environment, and measure to accuracies never before realized. It is important to know, not only what to measure, but how to measure it and then how to interpret the results.

Fiber optic signal transmission is solidly in the telephone industry and it is becoming more popular in the audio field as a method of transmitting signals with minimum noise, interference and increased security. This does not mean that hard-wired transmission will not be around for a long time. It is important to understand the characteristics of fiber optics, wire and cable and their affects on noise, frequency response and signal loss.

The guide also covers message repeaters, interpretation systems, assistive listening systems, intercoms, modeling and auralization, surround sound, and personal monitoring.

The sound level through mega-loudspeakers at rock concerts, through personal iPods, iPhones, and random noise from machinery, etc. is constantly increasing and damaging our hearing. The Audio Engineering Guide addresses this problem and shows one method of monitoring noisy environments.

Many of us know little about our audio heritage, therefore a Section is dedicated to sharing the history of these men who, through their genius, have given us the tools to improve the sound around us.

No one person can be knowledgeable in all the fields of sound and acoustics. This guide has been written by those people who are considered, by many, as the most knowledgeable in their field.