Which of the following is NOT a method for viewing the vocal folds?

Acoustic analysis is primarily a method used to study the sound waves produced during phonation and does not provide a direct view of the vocal folds. This technique involves analyzing the frequency, intensity, and waveform of vocal sounds, which can offer insights into voice quality and potential disorders but does not involve any physical examination of the vocal folds themselves.

In contrast, methods such as endoscopy, direct laryngoscopy, and indirect laryngoscopy involve direct or indirect visualization of the vocal folds. Endoscopy utilizes a flexible or rigid tube with a camera to visualize the larynx, while direct laryngoscopy allows for a more invasive view through the mouth, and indirect laryngoscopy typically involves using mirrors to view the vocal folds. Each of these techniques provides a visual examination, making them appropriate for assessing the structural and functional aspects of the vocal folds.