Since my last entry I have been into the studio to conduct some more experiments.
The first using CLIO, an electrical and acoustic measurement system, I played pink noise from a speaker at a number of different stereo arrays and measured the dBSPL from each microphone in the array for two different locations of the speaker- directly in front and 2 meters off to the side. By comparing the difference between levels for the pair of microphones the ability of each technique to localise sound based on level differences could be assessed.
The next experiment involved setting up the microphone techniques one at a time and playing a short burst of sound from 4 different locations within the room. These signals were recorded into Pro-Tools and then later by zooming in and using the selector tool to measure the difference in samples between the two microphones within a pair the time difference was calculated. This gave some interesting results showing which techniques use time delays for localisation.
The combination of these two experiments have led me to choose a different room for my final recording, although I would like to use the SSL AWS 900 that comes with the room, it just isn't wide enough to get a large enough stereo field. I've spoken to some local string groups and it seems I will be creating my final recordings at some point in mid march.
My research is continuing, now moving forward to investigate the processes involved with reproducing stereo sound. Today I have been focusing on loudspeakers and the problems of acoustic crosstalk as well as reading a lot about transaural stereo- the process of recreating three dimensional virtual sound sources all around the listener using just two sound sources located infront of the listener. It's very clever but the research indicates it sounds quite unnatural to the listener and tends to cause fatigue pretty quickly.
Tomorrow I will move onto investigating binaural and headphone stereo, I've already found some fascinating albums recreating Rachmaninov piano concertos recorded in both standard stereo and binaural and the differences between them are striking.