American Scientist

A slow beat thrums through a person’s body as they listen to music with headphones. Wearing a vest that creates vibrations in time with the music, the cochlear implant user sways and closes their eyes to take it all in. Later, they describe having felt immersed in the music, a rare occurrence, and say that the vibrations made the listening experience more intense.

Those who have cochlear implants are not new to feeling a lack of engagement in the media they consume on a day-to-day basis. For instance, cochlear implant users are known to have difficulty interpreting and understanding differences in the pitch, tone, and melody of music. Although plenty of research has focused on how cochlear implant users perceive music, fewer studies have examined what emotions these users feel during their listening experience.

Computer scientist Luca Turchet at the University of Trento in Italy and his colleagues at University Hospital of Verona wanted to explore how vibrational stimuli can help bring out emotions in the listening experience of cochlear implant users. “I was working with a doctor on a project that was not about music, but was still about the impact of sounds in interactive contexts on this population of cochlear-implanted people,” Turchet says. “I proposed to him a study that aimed actually at investigating something different from what turned out to be in this paper.” Turchet and his colleagues ended up altering their study because of a fortuitous finding. As the team reported in the journal Scientific Reports, they found that not only did participants report feeling more engaged in music when they wore a vibrational vest, but they also showed improvements afterward in understanding speech.

As Turchet recounts, they did an initial trial of the vest on a patient who had come in for his regular monitoring appointment. “He took the audiometric test that he was supposed to take anyway, and at that moment we understood that the performances of that person were very different from the average performances that he had in the past.” Repeating the trial with the vest on other patients consistently showed improved speech comprehension results. “So it was by chance, essentially, but also by being careful to notice that there was something important,” Turchet says.

Participants of this study were divided into two groups, both of which completed the same set of surveys and audio tests before and after listening to music. The participants were tested on how well they could hear tones or understand speech in both quiet and noisy conditions. Both groups listened to music samples that ranged from classical music to heavy metal, but only one of these groups wore the vibrating vest during listening. The vest translated the bass frequencies heard in the music into a signal that could be felt physically through vibrations created with motorized actuators embedded in the vest, which converted the electrical signal from the digitized music into synchronized mechanical motion.

Turchet and his colleagues had expected that participants might experience what’s called auditory fatigue after listening to music, and perhaps do worse on speech comprehension. Turchet thinks the explanation for the opposite finding is what’s called multisensory integration. He explains that the brain can combine auditory and somatosensory information. Because individuals with hearing deficits have a loss of one sense, stimulation of other senses such as touch allows for better stimulation of certain processing regions of the brain.

Not everyone who wore the vibrating vest preferred the experience; some users found the vibrations to be too intense. Turchet thinks that having a vest with adjustable levels of vibration might make the combined listening–vibration experience more tunable to the specific user’s preferences and improve results. Turchet also notes that studies on more users over longer periods of time will give them more reliable data on what works best for cochlear implant users.

In addition to a more immersive music experience for cochlear implant users, the results with speech comprehension indicate to Turchet and his colleagues that this approach could be the basis for developing new trainings. Studies conducted for longer periods of time could determine how much exposure to vibration stimuli is needed to show improvement in speech understanding.

“I hope that this result, which to me seems so encouraging, turns out to be useful for this category of users in some new forms of rehabilitation therapies,” Turchet says. “These technologies lead to deeper immersion in musical experience, and also a higher level of arousal, so I think it is promising.”