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Tactile stimulation has been shown to increase auditory loudness judgments in listeners. This bias could be utilized to enhance perception for people with deficiencies in auditory intensity perception, such as cochlear implant users. However, several aspects of this enhancement remain uncertain. For instance, does the tactile stimulation need to be applied to the hand or body, or can it be applied to the wrist? Furthermore, can the tactile stimulation both amplify and attenuate the perceived auditory loudness? To address these questions, two loudness-matching experiments were conducted. Participants matched a comparison auditory stimulus with an auditory reference, either with or without spectro-temporally identical tactile stimulation. In the first experiment, fixed-level tactile stimulation was administered to the wrist during the comparison stimulus to assess whether perceived auditory loudness increased. The second experiment replicated the same conditions but introduced tactile stimulation to both the reference and comparison, aiming to investigate the potential decrease in perceived auditory loudness when the two tactile accompaniments were incongruent between the reference and comparison. The results provide evidence supporting the existence of the tactile loudness bias in each experiment and are a step towards wrist-based haptic devices that modulate the auditory dynamic range for a user. [ABSTRACT FROM AUTHOR]

Cochlear implant (CI) users often report being unsatisfied by music listening through their hearing device. Vibrotactile stimulation could help alleviate those challenges. Previous research has shown that musical stimuli was given higher preference ratings by normal-hearing listeners when concurrent vibrotactile stimulation was congruent in intensity and timing with the corresponding auditory signal compared to incongruent. However, it is not known whether this is also the case for CI users. Therefore, in this experiment, we presented 18 CI users and 24 normal-hearing listeners with five melodies and five different audio-to-tactile maps. Each map varied the congruence between the audio and tactile signals related to intensity, fundamental frequency, and timing. Participants were asked to rate the maps from zero to 100, based on preference. It was shown that almost all normal-hearing listeners, as well as a subset of the CI users, preferred tactile stimulation, which was congruent with the audio in intensity and timing. However, many CI users had no difference in preference between timing aligned and timing unaligned stimuli. The results provide evidence that vibrotactile music enjoyment enhancement could be a solution for some CI users; however, more research is needed to understand which CI users can benefit from it most. [ABSTRACT FROM AUTHOR]

Music listening experiences can be enhanced with tactile vibrations. However, it is not known which parameters of the tactile vibration must be congruent with the music to enhance it. Devices that aim to enhance music with tactile vibrations often require coding an acoustic signal into a congruent vibrotactile signal. Therefore, understanding which of these audio-tactile congruences are important is crucial. Participants were presented with a simple sine wave melody through supra-aural headphones and a haptic actuator held between the thumb and forefinger. Incongruent versions of the stimuli were made by randomizing physical parameters of the tactile stimulus independently of the auditory stimulus. Participants were instructed to rate the stimuli against the incongruent stimuli based on preference. It was found making the intensity of the tactile stimulus incongruent with the intensity of the auditory stimulus, as well as misaligning the two modalities in time, had the biggest negative effect on ratings for the melody used. Future vibrotactile music enhancement devices can use time alignment and intensity congruence as a baseline coding strategy, which improved strategies can be tested against. [ABSTRACT FROM AUTHOR]

This study aimed to investigate differences in audio-visual (AV) integration between cochlear implant (CI) listeners and normal-hearing (NH) adults. A secondary aim was to investigate the effect of age differences by examining AV integration in groups of older and younger NH adults. Seventeen CI listeners, 13 similarly aged NH adults, and 16 younger NH adults were recruited. Two speech identification experiments were conducted to evaluate AV integration of speech cues. In the first experiment, reaction times in audio-alone (A-alone), visual-alone (V-alone), and AV conditions were measured during a speeded task in which participants were asked to identify a target sound /aSa/ among 11 alternatives. A race model was applied to evaluate AV integration. In the second experiment, identification accuracies were measured using a closed set of consonants and an open set of consonant-nucleus-consonant words. The authors quantified AV integration using a combination of a probability model and a cue integration model (which model participants' AV accuracy by assuming no or optimal integration, respectively). The results found that experienced CI listeners showed no better AV integration than their similarly aged NH adults. Further, there was no significant difference in AV integration between the younger and older NH adults. [ABSTRACT FROM AUTHOR]

McKay, Henshall, Farrell, and McDermott [J. Acoust. Soc. Am. 113, 2054-2063 (2003)] developed a practical method to estimate the loudness of periodic electrical signals presented through a cochlear implant. In the present work, this method was extended to time-varying sounds based on two models of time-varying loudness for normal listeners. To fit the model parameters, loudness balancing data was collected with six cochlear implant listeners. The pulse rate of a modulated pulse train was adjusted to equalize its loudness to a reference stimulus. The stimuli were single-electrode time-limited pulse bursts, repeated at a rate of 50 Hz, with on-times varying between 2 and 20 ms. The parameters of two different models of time-varying loudness were fitted to the results. For each model, parameters defining the time windows over which the electrical pulses contribute to instantaneous loudness were optimized. In each case, a good fit was obtained with the loudness balancing results. Therefore, the practical method was successfully extended to time-varying sounds by combining it with existing models of time-varying loudness for acoustic stimulation. [ABSTRACT FROM AUTHOR]