Welcome to the jungle: Aesthetic preference mediates soundscape evaluation, with limited effects of ultrasound exposure

Listening to nature soundscapes has been associated with aspects of psychological restoration, including increased cognitive performance and positive affect. Most recordings of these environments, however, are limited to the audible frequency range (i.e., 20 Hz – 20 kHz), which leaves open the question of whether frequencies beyond the range of human hearing (ultrasound) influence psychological restoration. Ultrasound has been associated with increased alpha wave activity in the brain, which in turn has been associated with decreased stress and a state of relaxed alertness, suggesting that ultrasound might augment the restorative potential of soundscapes. To investigate this, we conducted a randomized controlled trial ( n = 111) comparing different types of soundscapes (nature, recorded in a Borneo rainforest, or urban, recorded in a city in Ontario) with different bandwidths (audible-only or audible plus ultrasound) to quantify their effects on cognitive performance (backward digit span, n -back), self-reported mental fatigue, affect, and perceived restoration. During the sound intervention, participants additionally aesthetically rated the soundscapes. The results revealed no significant effects of ultrasound or environment on cognitive performance. However, ultrasound exposure increased mental fatigue. Additionally, there was no effect of ultrasound on either affect or perceived restoration. Notably, although nature soundscapes facilitated affective and perceived restoration, these effects were driven by participants’ aesthetic ratings of the soundscapes. • Ultrasound did not enhance cognitive, affective, or perceived restoration outcomes • Ultrasound exposure increased self-reported mental fatigue across soundscapes • Nature soundscapes buffered affective decline but did not improve cognition • Perceived restorativeness of nature sounds decreased when ultrasound was present • Aesthetic preference, not environment type, best predicted restorative outcomes