Article Outline

1. INTRODUCTION
2. REVIEW OF MEASUREMENT TECHNIQUES
3. THEORY OF ACOUSTIC IMPEDANCE MEASUREMENTS
4. CALIBRATION OF IMPEDANCE HEADS
   1. Review of calibration techniques
   2. General calibration technique using up to three resonant-free loads
   3. Choice of calibration loads
5. ERRORS
   1. Inadequate spectral resolution
   2. Nonlinear transducer responses
   3. Diameter mismatch at the reference plane
   4. Random noise (acoustical or electrical)
   5. The “singularity factor”
   6. Calculating the error in Z
6. OPTIMIZATION OF THE OUTPUT SIGNAL
7. MATERIALS AND METHODS
   1. The impedance spectrometer
   2. Calibration loads
8. RESULTS AND DISCUSSION
   1. Effect of optimizing the output signal
   2. Effect of calibration
   3. Conclusions and practical considerations for measurement