You can train your brain to hear better, scientists have found

The way we perceive music and speech is different from what we have believed until now. (CREDIT: Creative Commons)

Those who struggle to understand a person telling an agitated, fast-paced tale of adventure, or who lose the thread of a conversation during a rowdy cocktail party, may have trouble detecting rapid changes in sound, and a new study from the University of Maryland may help.

In a recent study published in the Journal of the Association for Research in Otolaryngology (JARO), researchers from the Department of Hearing and Speech found that people aged 18-30 and 65-85 with normal hearing, as well as participants in the older age group with impaired hearing – they can all be trained to increase their ability to distinguish subtle changes in the speed or “frequency” of sounds. Such changes can make speech intelligibility difficult in difficult situations, such as in noisy or reverberant environments, or when listening to fast-talking people.

“We have seen some evidence that this temporary processing deficit can be improved in animal models, but this is the first time we have demonstrated this in humans,” said Associate Professor Samira Anderson, lead author of the publication. Among her co-authors are professors Matthew Gupell and Sandra Gordon-Salant.

For training, participants in an experimental group of 40 compared several series of fast sounds (such as beeps or clicks) over nine sessions over three weeks. Compared to members of a control group of 37 who were asked to detect one tone in , members of the experimental group showed an overall improvement.

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Most importantly, older adults with normal hearing who receive training can essentially regain their ability to distinguish between rapid changes in time of sounds to a level similar to that seen in younger people.

This Frequency Discrimination Study is one of three UMD projects funded by an $8.2 million Neuroplasticity and Auditory Aging Program grant awarded in 2017 to Gordon-Salant, director of the UMD Hearing Research Laboratory and Principal Investigator of the projects. Each aims to explore how an aging brain contributes to auditory and speech difficulties, and ultimately whether targeted auditory and cognitive training can help restore effective auditory processing—with very different approaches.

Listeners

We recruited 301 participants in a double-blind, randomized, controlled clinical trial and determined whether they met the following age and audiometric criteria for these groups: young normal hearing (YNH, age 18–30 years), elderly normal hearing (ONH, age 65–30 years) ). 85 years old) and older people with hearing impairments (OHI, age 68–85 years).

Normal hearing was defined as a pure tone threshold ≤ 25 dB HL (relative to: ANSI 2018) from 125 to 4000 Hz in the right ear. Hearing impairment was defined as an average pure high-frequency tone (average thresholds at 1, 2 and 4 kHz) > 30 dB HL and thresholds at 2 and 4 kHz < 70 dB HL (to ensure the signal is audible).

Hearing thresholds had to be symmetrical (no inter-auricular differences > 10 dB at any frequency) for all listeners, and also free of air-to-bone gaps > 10 dB at any frequency. Word recognition rates were >70% for one list of 25 words in the NU-6 test (Tillman and Carhart 1966), presented on a two-way basis at a noise level of 75 dB HL in silence.

Middle ear function was bilaterally normal based on mean tympanometric peak pressure, peak conductance, tympanometric width, and equivalent volume. Acoustic reflexes were present from 500 to 2000 Hz, evoked ipsilaterally and contralaterally. Finally, auditory brainstem responses (ABRs) were recorded and the V wave latency was <6,8 мс без интерауральной асимметрии >0.2 ms.

Additional criteria included the following: Montreal Cognitive Test (MoCA; Nasreddine et al., 2005) passing score ≥ 26, negative history of neurological disease, Snellen vision screening score ≤ 20/50 (Hetherington 1954). ), being a native English speaker and having received a high school diploma.

All procedures have been reviewed and approved by the Institutional Review Board (IRB) of the University of Maryland, College Park. The trainees provided informed consent and received monetary compensation for their time.

The 125 participants who met the study criteria were randomly assigned to one of two training groups: experimental and active control. Of these, 48 students did not complete the study. Seventeen trainees were suspended due to: non-compliance with the training regimen (3), poor data quality (7), an adverse event (1) and excessive time delay associated with COVID-19 (6).

Twenty-six participants withdrew from the study for medical or transportation reasons. Eleven listeners were lost to follow-up. The total number of participants in each training group was 40 experimental (14 YNH, 16 ONH and 10 OHI; 30 women) and 37 active controls (15 YNH, 14 ONH and 8 OHI; 28 women).

Note that 1% of the listener data (31 out of 2618 measurements) is missing due to isolated issues during data collection or due to anomalous data that did not converge.

Pre- and post-training phase lock factor (PLF) for 100 and 300 Hz is displayed in the time-frequency domain for young normal hearing (YNH), normal hearing older (ONH), and normal hearing older people. Impaired listeners (OHI) in the experimental (upper three panels) and active control (lower three panels) groups. (CREDIT: Journal of the Association for Research in Otolaryngology)

Findings:

The speed discrimination study showed for the first time that “auditory training promotes neural changes in the brain known as neuroplasticity,” Gordon-Salant said. “The results hold great promise for the development of clinically feasible auditory training programs that can improve the ability of older listeners to communicate in difficult situations.”

Gordon-Salant and colleagues are actively recruiting people with normal hearing or mild to moderate hearing loss to participate in the next phase of this speed discrimination study, as well as another study funded by the Neuroplasticity Grant, to see if memory requirements affect for efficiency. human education programs.

The third grant project, on the ability of aging animals to hear sounds in the midst of noise, is led by Shihab Shamma of the Department of Electrical and Computer Engineering and the Institute for Systems Research.

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Note: Materials provided above by the University of Maryland. Content can be edited for style and length.

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