Acoustics

Author: Eric Reuter | Course Code: OLMSC-215

Become a better recording and live sound engineer, and improve your editing and mixing environment by learning the ins and outs of acoustics. Proper acoustics plays a major role in the success of any musical performance, whether it’s in a recording studio, concert hall, or outdoors. This course is designed to introduce the fundamentals of acoustics, with a focus on spaces designed for recording music and live performance. Through both theoretical study and practical experimentation, you will learn the basics that contribute to good acoustics, including control of noise, manipulation of sound propagation, and isolation of sound. You will learn how to measure and quantify these key components in existing spaces, and how to predict acoustical behavior in new spaces.

The course begins with the basics of sound, sound sources, and human perception. It then explores the relationship between the source of sound and the listener in three different scenarios: source and listener outdoors, source and listener in a room, and source and listener in separate rooms. These scenarios provide comprehensive coverage of the principles relevant to music performance, recording, and mixing.

Each week, you will be assigned acoustical problems to solve. Note that the course explores a number of mathematical concepts. These concepts will be reviewed before you are required to use them for the first time. The goal of the course is to enable you to predict and analyze the acoustical qualities of both indoor and outdoor environments, so that you can make informed decisions about the use or design of spaces in which to play, record, and mix.

By the end of this course, you will be able to:

  • Relate your experience of sound to the physical attributes of the source and the propagation path between the source and your ears
  • Predict and quantify the behavior of sound in rooms, including the effects of reflections and reverberation on the clarity of music and the intelligibility of speech
  • Predict and quantify the effects of outdoor environments on sound propagation, including sound barrier walls and other obstacles
  • Understand the challenges of small room acoustics and their effects on recording and mixing environments
  • Calculate change in sound pressure level relative to distance
  • Understand the principles of sound isolation and be able to predict and measure isolation between rooms
  • Measure room acoustics parameters using both traditional and state-of-the-art techniques
  • Use a handheld sound level meter
  • Understand sound absorption
  • Understand the basic principles and requirements of vibration isolation and HVAC noise control
  • Use your knowledge of these principles to improve the quality of your recordings and the fidelity of your mixing environment

Lesson 1: The Properties of Sound

  • What Is Sound?
  • Waves
  • Graphing Waves

Lesson 2: Modes and Harmonics

  • Vibration and Modes
  • Representing Waveforms with Equations
  • Harmonics and Complex Waveforms
  • Modes and Harmonics

Lesson 3: Decibels and Octaves

  • Review of Logarithms
  • Octaves and Octave Bands
  • Decibels
  • Sound Pressure Level

Lesson 4: Sound Level Measurement

  • Adding Decibels
  • Equal Loudness Contours
  • Frequency Weighting
  • Sound Level Meters

Lesson 5: Sound Outdoors

  • Inverse Square Law
  • Source Models
  • When Sound Hits Things
  • Sound Barriers

Lesson 6: Room Acoustics

  • Sound Absorption
  • Propagation Indoors
  • Impulse Response
  • Reverberation Time

Lesson 7: Room Acoustics (Continued)

  • Room Constant
  • Critical Distance
  • Converting Power to Pressure

Lesson 8: Sound Indoors—Virtual Field Trip

  • Theater Overview
  • Measurement Equipment
  • Measurements
  • Data Analysis
  • Sound Reinforcement System

Lesson 9: Sound Isolation

  • Absorption vs. Isolation
  • Transmission Coefficient & Transmission Loss
  • Laboratory vs. Field Measurement
  • Mass Law and Coincidence Dip

Lesson 10: Sound Isolation Continued

  • Single-Number Descriptors
  • Composite TL
  • Decoupling & Damping
  • Practical Sound Isolation

Lesson 11: Small Room Acoustics

  • Standing Waves & Modes
  • Effect of Isolation on Standing Waves
  • Room Acoustics for Listening Environments

Lesson 12: Vibration and HVAC Noise

  • Vibration Isolation
  • HVAC Noise Sources
  • HVAC Noise Calculations
  • HVAC Noise Control

Eric Reuter

Author & Instructor

Eric Reuter has more than a decade of experience as a consultant and educator in acoustics. He operates an acoustical consulting firm in Portsmouth, NH, and has taught a variety of courses in acoustics and audio electronics at Berklee College of Music since 2000. His consulting spans a broad range of acoustical project work, including architectural acoustics and noise control, environmental noise, and vibration.

Reuter is a Board Certified Member of the Institute of Noise Control Engineering, serves on the Board of Directors of the National Council of Acoustical Consultants, and is an active member of the Acoustical Society of America. He spends his time off racing his sailboat, chasing trains, and tinkering with antique Volvos.

Prerequisites

Completion of Math for Musicians, or equivalent knowledge and/or experience.


Recommended Textbook

Master Handbook of Acoustics (6th edition) by Everst and Pohlmann, McGraw-Hill


Software Requirements

  • Calculator: can be either a hardware or software calculator, as long as it has a LOG function. Both Macs and Windows come with calculators built into the system, which are sufficient when switched to Scientific mode
  • Mac Web Browser: Firefox (Recommended), Chrome, or Safari
  • PC Web Browser: Firefox (Recommended), Chrome, Internet Explorer, or Edge
  • Flash Player (if using the Record Live tool)



Hardware Requirements

All Users

  • Basic handheld or smartphone app sound level meter
  • Good quality over-the-ear headphones or earbuds capable of reproducing 100-20,000 Hz.

Mac Users

  • OS X 10.7 or higher
  • 2 GB RAM
  • 500 MB hard drive space
  • Sound card
  • Webcam

PC Users

  • Windows Vista SP2 or higher
  • Intel Pentium 4 or higher
  • 1 GB RAM
  • 500 MB hard drive space
  • Sound card
  • Webcam

Comments

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Next Term Starts September 26


  • Level
  • Duration
    12 weeks
  • 3-Credit Tuition
    $1,479
  • or
  • Non-Credit Tuition
    $1,229

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