Moderate presbycusis boosts audio-visual integration, but not lip-reading.

Area of Science:

• Audiology
• Neuroscience
• Speech Perception

Background:

• Speech comprehension typically relies on auditory input alone.
• Real-world communication involves audio-visual (AV) integration, especially with degraded auditory signals due to hearing loss (HL) or noise.
• The impact of HL and aging on AV speech integration is not well understood.

Purpose of the Study:

• To investigate the effects of HL and age on unimodal visual (lip-reading) and bimodal (AV) speech processing.
• To determine how HL and aging influence audio-visual gain, a measure of AV integration.
• To disentangle the independent and interactive effects of HL and age on speech perception.

Main Methods:

• Sixty-five participants aged 50+ with normal to moderate HL were tested.
• Speech comprehension was assessed in auditory, visual, and AV conditions using an adaptive procedure.
• Multiple linear regressions and causal inference were used to analyze the impact of HL and age.

Main Results:

• Mild to moderate HL did not improve unimodal visual speech processing.
• Mild to moderate HL significantly improved audio-visual gain.
• Aging negatively impacted visual speech processing but did not directly affect AV gain.

Conclusions:

• Mild to moderate HL enhances AV speech integration, improving overall AV performance.
• Age-related decline in visual processing does not impair AV integration.
• These findings suggest central plasticity in response to HL, potentially counteracting age-related sensory decline.