How is ANL Different from Signal-to-Noise Ratio Scores

Question

Answer

ANL is simply not an intelligibility task. I think that Audiologists have spent so much time working towards improving intelligibility in noise with various products that it is hard to get past the idea that ANL does not measure intelligibility. When someone is using the HINT or SPIN or QuickSIN, they are getting a very definite score. As an example, the HINT measures the level at which the patient can correctly identify 50% of sentences. An ANL is a little more subjective. You have to remember that our instructions are "...select the level of background noise that is the MOST you would be willing to accept of "put-up-with" without becoming tense and tired while following the story." This is very different than straining to get 50% correct, regardless of the signal-to-noise ratio. When an ANL is measured the listener may be identifying 40% or 50% or 60% of what the talker is saying to understand the story and tolerate the amount of noise that is present. This has been supported by our research in that we do not see a relationship between scores from tests like the HINT and ANLs. In other words, ANLs and speech perception tests measure two different reactions to background noise.

If you would like additional information on the ANL measurement, please visit our lab's website at web.utk.edu/~aspweb/faculty/nabelek/anl.shtml

Melinda C. Freyaldenhoven, Ph.D., CCC-A (Assistant Professor): Mindy earned the Ph.D. degree in Speech and Hearing Science from The University of Tennessee (Knoxville) in 2006. She is currently an Assistant Professor at Louisiana Tech University (Ruston).

Patrick N. Plyler, Ph.D., CCC-A (Assistant Professor): Patrick earned the Ph.D. degree in Speech and Hearing Science from The University of Tennessee (Knoxville) in 1998. He then moved to Louisiana State University (Baton Rouge), where he was an Assistant Professor for 5 years. In 2004, Patrick returned to The University of Tennessee (Knoxville) as an Assistant Professor.