A paper presented at the Institute of Acoustics Reproduced Sound 25 conference in 2009 looking at the response of two SoundField Ambisonic microphones to sound sources at different distances from the microphone.

1. Reproduced Sound 25 Dr Bruce Wiggins Tom Spenceley Signal Processing Applications Research Group University of Derby DISTANCE CODING AND PERFORMANCE OF THE MARK 5 AND ST350 SOUNDFIELD MICROPHONES AND THEIR SUITABILITY FOR AMBISONIC REPRODUCTION [email_address] http://www.derby.ac.uk/staff-search/dr-bruce-wiggins

9. NFC Filters for 1m (solid) and 3m source with a speaker distance of 1.5m

11. Why would the Mics be different? – A to B Format Pre-filter A Pre-filter B Pre-filter C Pre-filter D Degree 0 Filter Degree 1 Filter Degree 1 Filter Degree 1 Filter W = (A+B+C+D) X = (A+C)–(B+D) Y = (A+B)–(C+D) Z = (A+D)–(B+C)

13. Results – ST350

14. Results - ST350

15. ST350 Calibration Amplitude

16. ST350 Calibration Phase

17. Results - MKV

18. Results – MKV

19. Results – MKV Amplitude

20. Results – MKV Phase