Technical Papers

  • Acoustics and Psychoacoustics
  • Acoustic Simulation
  • Audio Electronics
  • Headphone Systems

Acoustics and Psychoacoustics

Title: The Elements of Musical Perception
Author: HeadWize
An introduction to acoustics and psychoacoustics with a section on 3D hearing. Examples are selected for relevance to audiophiles.

Title: 3-D Audio Primer
Author: Aureal Corporation
This paper compares different 3D audio technologies (extended stereo, surround sound, positional 3D audio) and includes a section on the basics of 3D hearing.

Title: The Psychoacoustics of Headphone Listening (HeadRoom White Paper)
Author: HeadRoom Corporation
Why headphones sound different from loudspeakers and how crossfeed processing can improve headphone sound.

Acoustic Simulation

Title: Technologies for Surround-Sound Presentation in Headphones
Author: HeadWize
Tracing the development of 4-channel headphone and acoustic simulators for playback of 3-D sound in headphones. Includes discussion of the inventions of Ohta; König; Bauer; Asahi; Brungart; Lowe; Tucker and Green; McGrath; Turner; Cohen; Iwahara and Klayman – from patent disclosures and technical papers.

Title: Surround Enhancement Processing for Stereo Loudspeakers
Author: Mike Sokol
A look at Spatializer, a single-ended enhancement processor for recording and playback of 3D sound from 2 channels. The author discusses its theory of operation and its effects.

Title: High Resolution Simulation of Acoustic Environments
Author: David McGrath, Lake DSP Pty, Ltd.
An overview of issues for high quality audio simulation of Virtual Reality. Computer synthesis of room acoustic responses is reviewed with emphasis on Virtual Reality.

Title: Creation, Manipulation and Playback of Soundfields
Author: Andrew Reilly and David McGrath (Lake DSP Pty, Ltd.)
This paper explains basic methods used in soundfield recording and playback (B-Format Ambisonics). The research merges technologies from Architectural Acoustics (Auralization) and Virtual Reality (head-tracking and 3D simulation).

Title: Convolution Processing for Realistic Reverberation
Author: Andrew Reilly and David McGrath (Lake DSP Pty, Ltd.)
Arbitrary reverberation impulse responses may be applied to real time audio data by the use of long convolution. This paper outlines the techniques for measuring, generating and manipulating reverberation functions. In addition, some less traditional functions are proposed as reverberation impulse responses for use as musical effects.

Title: Dolby Pro Logic Surround Decoder: Principles Of Operation
Author: Roger Dressler (Dolby Labs)
A discussion of theory and operation of Dolby Surround and Dolby Pro Logic decoders.

Title: Dolby Digital: The Sound Of The Future-Here Today
Author: Dolby Labs
This paper outlines the theory and operation of Dolby Digital (AC-3).

Title: 3D Audio and Acoustic Environment Modeling
Author: William G. Gardner
A discussion of 3D audio reproduction over loudspeakers and in headphones with special focus on the acoustic environment modeling technology developed by Wave Arts, Inc. and Dr. William Gardner. General 3D audio topics include: binaural synthesis, crosstalk cancellation, and reverberation algorithms.

Title: Virtual Audio For Headphones
Author: Alastair Sibbald
This paper examines the role of HRTFs in headphone virtualization with special attention to the differences between 3D audio reproduction from loudspeakers and in headphones.

Title: Chaotic Waves for 3D Audio
Author: Alastair Sibbald
In spatial hearing, the indirect sounds (which arrive at the ears after the direct sounds) are reflected and scattered in a complex pattern and are called chaotic waves. This paper discusses the importance of chaotic waves to spatial hearing and synthesis of chaotic waves in interactive acoustic simulation environments in headphones.

Audio Electronics

Title: Understanding Headphone Power Requirements
Author: Dennis Bohn, Rane Corporation
Much confusion abounds regarding headphone power requirements. How much power is really needed for your application?

Title: Sound System Interconnection
Author: Rane Corporation Technical Staff
How to hook up audio equipment without suffering through all sorts of bizarre noises, hums, buzzes, whistles, etc.

Title: Signal Processing Fundamentals
Author: Dennis Bohn, Rane Corporation
The basics of crossover networks, equalizers and dynamic controllers (compressors, expanders, etc.).

Title: Why Not Wye
Author: Dennis Bohn, Rane Corporation
Tips for using Y-connectors to split and sum signals. Has plans for balanced and unbalanced summing boxes – with section on summing low signals to drive subwoofers.

Title: Setting Sound System Level Controls
Author: Dennis Bohn, Rane Corporation
Correctly setting a sound system’s gain structure is one of the most important contributors to creating an excellent sounding system. A dozen possible procedures exist for correctly setting the gain structure of any system. The fundamental principles are applicable to different system configurations.

Title: Digital Dharma of Audio A/D Converters
Author: Dennis Bohn, Rane Corporation
A primer on digital audio and the workings of analog-to-digital converters.

Headphone Systems

Title: Technologies for Surround-Sound Presentation in Headphones
Author: HeadWize
Traces the development of 4-channel headphone and acoustic simulators for playback of 3-D sound in headphones. Includes discussion of the inventions of Ohta; König; Bauer; Asahi; Brungart; Lowe; Tucker and Green; McGrath; Turner; Cohen; Iwahara and Klayman – from patent disclosures and technical papers.

Title: In-Ear Monitoring
Author: Garwood Communications
The concepts, operation and applications of in-ear monitoring systems. Includes a FAQ and discussion of hearing conservation issues.

Title: Active Noise Reduction Headphone Systems
Author: A HeadWize Design Paper
Theory and implementation of noise cancellation headphones with attention to open-loop, closed-loop and adaptive systems. Includes discussion of the inventions of Williams, Kyle, Bose, Sapiejewski, Bartels, Eriksson, Feintuck and Lo – from patent disclosures and technical papers.

Title: Adaptive Active Noise Control for Headphones Using the TMS320C30 DSP
Author: Angela Kuo Wang and Benedict Tse
Adaptive noise controller for headphones implemented on a Texas Instruments DSP. Superior performance over fixed noise control due to the tracking capabilities of the controller in response to surrounding noise. This document is currently available in PDF format only (courtesy of Texas Instruments).

Title: High Impedance Headsets for Crystal Radios
Author: Alan R. Klase
A spec comparison of various old-style high impedance headsets with specific application to use with crystal radios.