The ratio of the response or amplitude from signals of interest to the response or amplitude of indications that contain no useful information for the test being conducted is referred to as:

The response or amplitude from signals of interest in an inspection context can be significantly affected by unwanted indications, often referred to as noise. The signal-to-noise ratio quantifies the relationship between the useful signal and the background noise. A higher signal-to-noise ratio indicates that the useful signal is much stronger than the noise, which allows for more reliable and accurate interpretations of the data collected during testing.

This concept is crucial in non-destructive testing techniques, where distinguishing between relevant test indications and irrelevant noise is essential for obtaining valid results. Understanding and maximizing the signal-to-noise ratio helps technicians identify meaningful signals related to potential defects or areas of concern, ultimately leading to better assessments of the integrity of the material or structure being tested.