Meeting Topic: "Achieving Better Sound in the Digital Age"
Speaker Name: Graham Boswell - Prism Sound
Meeting Location: Devlin Hall, Boston College Campus, Chestnut Hill MA
Boston AES Meeting
One Tues. Nov. 9th, 2010, the Boston Section of the Audio Engineering Society featured Graham Boswell with his presentation "Achieving Better Sound in the Digital Age". He addressed the subjective perception of "good quality sound" and how the accuracy of reproduction can be affected.
Our ability to perceive tones is different at different loudness levels. Masking can interfere with how we perceive sound. Graham ran a sweeping tone on one channel and a quieter constant tone on another channel. The example showed an area during the sweep where the constant tone disappears.
Dithering adds noise to the signal to give us more to work with which influences the resolution more accurately. If a sine wave were only loud enough to complete one step of quantization, it would in fact be a square wave. The amplitude cannot be controlled within that step. Graham played examples of dithering and compared with non-dithered examples at various sample rates.
Synchronizing should not change the sound but simply lock. Accurate synchronizing between digital devices is critical so that we don't get phase distortion and drifts in frequency between channels in different boxes. Graham concluded with some examples of "Psycho-Acoustic Trickery" showing that we can't always trust what we perceive.
Graham Boswell is the original founder of Prism Sound and currently manages the business in partnership with Chief Technology Officer Ian Dennis. He graduated in Electronic Engineering Design and Production from Middlesex Polytechnic in the UK and is an experienced Electronics Engineer and an audio enthusiast. Prior to working in the audio industry, Graham worked on avionics projects for GEC-Marconi, missile guidance systems for British Aerospace and ISDN digital telecoms projects for Marconi Communications. Graham then joined Neve Electronics Labs of Cambridge, UK, where Graham and Ian Dennis worked on ground-breaking digital audio mixers during the early and mid-1980's.
At Neve, Graham was responsible for designing the "Digital Transfer Console - DTC-1". Graham's work included adapting the Neve digital equalizer and dynamics processing for mastering applications as well as developing a time code-based moving fader automation system with snapshot capability for EQ, dynamics and routing.
Graham was looking for new challenges and founded Prism Sound as an engineering consultancy, conducting research and development projects for a range of clients including Neve. The company branched out into other areas including radar, optical disk technology and lighting systems but the core expertise remained audio technology. At the time, new products included the AD-1 high-end A/D converter and the DSA-1 digital audio interface. Prism Sound also introduced a digital Fast Fourier Transform (FFT) analyzer in 1993 named "dScope" and this evolved to become the "dScope Series III" analogue & digital audio analyzer, released in 2003.
Written By: Tony Schultz