TABLE OF CONTENTS 



ABSTRACT 1 



INTRODUCTION 1 



EXPERIMENTAL APPARATUS 2 



The Wind Tunnel 2 



The Pressure Transducer 3 



Electrical Equipment 4 



EXPERIMENTAL RESULTS 5 



Spectral Density of the Pressure Fluctuations 5 



Longitudinal Cross Spectral Density 7 



THE TRANSVERSE CORRELATION 12 



REFERENCES 12 



LIST OF ILLUSTRATIONS 



Page 



Figure 1 — Schematic of Adaptation of the Altec 21-BR-180 Microphone 



for Spectral Density Measurements 3 



Figure 2 - Schematic of Microphone Adapted for Cross Spectral 



and Correlation Measurements 3 



Figure 3 — Schematic Diagram of the Equipment Used in the Measurement 



of the Cross Spectral Density 4 



Figure 4 — Spectral Density of the Pressure Fluctuations 6 



Figure 5 — Real and Imaginary Parts of the Longitudinal Cross Spectral Density. ... 9 



Figure 6 — Longitudinal Coherence of the Pressure Fluctuations 11 



Figure 7 — Transverse Correlation Function 12 



