Steady-state noise, such as the constant hum of an air conditioner, fan, or car engine, is generally easier for the noise reduction algorithms in hearing aids to manage because its acoustic characteristics are stable over time. Therefore, a hearing aid should be more successful at reducing these types of noise compared to transient or fluctuating noise sources, which change rapidly over time.
By reducing steady-state sounds, hearing aids can enhance the contrast between speech and background noise. However, the actual improvement in speech recognition will depend on several factors, including the user's degree of hearing loss, the characteristics of the noise, the quality and sophistication of the noise reduction algorithm, and the individual's ability to adapt to and benefit from the technology.
It's important to note that while noise reduction can help with speech recognition, it's not a perfect solution. Noise reduction algorithms can sometimes inadvertently reduce some aspects of speech, which can make it harder for the listener to understand. Also, there are limitations in reducing non-steady state noises like those coming from multiple talkers in a crowded room. DNR can also negatively affect music listening.
Given the limited benefits in noisy situations like restaurants, DNR should not be considered a viable solution to the cocktail party problem. However, DNR can greatly improve listening comfort by reducing the annoyance of noise, including background chatter.1, 3, 8