If you have clients who are particularly concerned about being able to understand speech in noisy environments, you might want to explore the potential of a new test. It can help estimate how satisfied users will be with a hearing aid in real-life, noisy surroundings. 
Called a Tracking of Noise Tolerance (TNT) test, it’s a computerised, automatic procedure that simply and reliably measures what any person considers tolerable noise. In other words, it determines how much effort the listener has to make to be able to hear.

We hypothesise that the more noise a person can put up with, the less effort it takes to remain engaged in a noisy situation. Knowing how much noise someone can tolerate while ensuring acceptable speech understanding could predict if they’ll be successful communicating in noisy situations.

So, the TNT test can validate the potential success – or failure – of a fitted hearing aid to help the wearer distinguish speech in loud noisy environments.
How the TNT test works
The TNT software runs on any Microsoft Windows-based computer – preferably attached to two loudspeakers. Your client will need access to the keyboard, and you should conduct the TNT test in a quiet setting.

The client wears their current or potential hearing aids during the test. The hearing aids must already have been fitted.

First, the computer plays a test passage to make sure the client understands at least 90 percent of the passage they are hearing. Then it plays a new passage on the same topic, but with the noise level gradually increasing.

The test tracks the tolerable noise level (TNL): the loudest noise level that the client is able and willing to “put up with” without sacrificing speech understanding over a 2-min period. The higher the TNL, the more the client can tolerate loud noise and still understand speech.
What you can use the test for
In addition to predicting whether the client will be satisfied using hearing aids in real-life noisy situations, you can also use the TNT test to:

  • Identify whether clients potentially cannot tolerate loud sounds
  • Select/adjust hearing aid features
  • Evaluate the efficacy of hearing aid features
  • Compare differences in activation times between signal processing algorithms
  • Evaluate whether the client is growing more or less tolerant towards sound after using the hearing aids for some time, indicating whether hearing aid acceptance has improved
Although you often can improve your clients’ ability to hear in noisy situations (using directional microphone, noise reduction options, etc.), even that doesn’t solve the problem for some hearing aid users. Why?
Effortless Hearing
Studies by Widex and others have shown that noisy environments increase the cognitive load on listeners, so more effort is needed to maintain successful communication – which often causes fatigue. That’s why we incorporate Effortless Hearing  into the design of our product s.

We’ve experimented with the TNT test as part of our research into Effortless Hearing.

Interested in the test?
You’re welcome to download a far more detailed article in Hearing Review on using TNT as an outcome measure for hearing aids. Please contact for additional information.

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