In the present study, we conducted voice therapy using telepractice on patients with hyperfunctional voice disorder and identified vocal improvement based on multi-dimensional vocal evaluations. In addition, interview-based qualitative analysis was performed for the in-depth analysis of voice therapy using telepractice. The findings of the study were as follows.
4.1. Identification of Vocal Improvement through Vocal Evaluations
According to the GRBAS scale, which was used for auditory–perceptual evaluation, the results showed decreases in values for G, R, and B parameters. According to most previous studies, voice therapy using telepractice showed improvement based on auditory–perceptual evaluation [
3,
10,
11], which is consistent with the findings of the present study. Therefore, voice therapy using telepractice showed a positive effect based on auditory–perceptual evaluation.
In the acoustic evaluation, the results showed an increase in F0 and decreases in jitter, shimmer, and NHR. Before treatment, the F0 of Participants A and C was lower than that of typical adult females. However, after treatment, the F0 increased to indicate vocal improvement. It is suspected that the F0 increased as a result of a reduction in vocal cord weight due to the reduction or removal of lesions through treatment. Moreover, decreases in jitter, shimmer, and NHR also indicated improvement in voice quality. Such findings were consistent with those of a previous study reporting a significant decrease in jitter and shimmer in patients with vocal polyps after applying multi-voice therapy techniques [
4]. Although the treatment was not performed face to face like the previous study, the present study reconfirmed the effectiveness of voice therapy using telepractice by demonstrating the same improvement in voice quality. Additionally, VRP results showed expanded pitch range, which was also reported in a study in which patients with hyperfunctional voice disorder underwent a vocal aerobic treatment program [
17]. In the present study, the pitch range expanded, particularly at high frequencies, which may be explained by two reasons. Firstly, treatment that induced relaxed vocalization improved vocal function to a normal level, and as a result, the F0 increased, while the vocalizable high-frequency range also expanded. Secondly, among the therapeutic techniques applied to the participants, VFE focused on gliding. Accordingly, because stretching training was carried out while controlling all laryngeal muscles and improving flexibility, such training was able to induce high-pitched sound to be produced naturally.
In the aerodynamic evaluation, the MPT increased, while the MAFR and the Psub appeared within the normal range after treatment. This can be viewed as improvement from enhanced respiration after voice therapy using telepractice. A case study on application of voice therapy using telepractice on children with voice disorder caused by septic pharyngitis and flu reported that the MPT increased from 6.7 to 15 s after 12 sessions of voice therapy [
10]. Resonant voice therapy, VFE, and SOVTE were applied, and after treatment, the MPT increased, while hoarseness and strained voice were relieved. As in the previous study, the holistic voice therapy used in the present study focused on coordination between respiration, phonation, and resonance to promote proper vocalization. Consequently, increase in the MPT and improvement in voice quality were achieved.
Meanwhile, Participants B and C showed MAFR within the normal range regardless of treatment. However, Participant A showed an MAFR of 30 mL/s before the treatment, which increased to 80 mL/s after treatment, which was within the normal range. This result could be interpreted as the treatment promoting vocalization with the goal of relaxation being able to bring positive change to vocal function by relieving tension. Moreover, Participant C showed a decrease in the Psub from 13.98 cmH2O before treatment to 8.11 cmH2O after treatment, which was within the normal range. This result can also be interpreted as treatment with the goal of relaxation being able to improve the usual habit of uttering words forcefully and with tension.
In the patient self-evaluation using the VHI, participants showed lower scores in functional, physical, and emotional domains. It is suspected that participants felt that their voice had improved after voice therapy using telepractice. Previous studies have also reported that patients felt that the severity of their vocal problems were reduced after voice therapy using telepractice [
3,
17,
18]. In particular, Participants A and B showed decreases of at least 22 points in their scores for the physical domain, and as a result, they showed a much greater margin of decrease than Participant C, showing a difference of at least 47 points in their overall scores. The severity of voice disorder perceived by each person is different. Participants A and B, who were occupational voice users, responded more sensitively to vocal changes than Participant C, who was a non-occupational voice user. Both Participants A and B perceived their vocal problems to be more serious than Participant C before treatment, and thus, they accepted the vocal changes after therapy using telepractice to be more significant. In other words, such findings could be understood as occupational voice users showing more positive acceptance of the effects of voice therapy using telepractice.
4.2. Interview-Based Qualitative Analysis
Firstly, the participants in the voice therapy using telepractice had doubts about the effectiveness of telepractice before starting treatment. However, they expressed satisfaction upon completion of treatment. The common factor that was satisfactory for all participants was not having to get ready for treatment since patients did not need to allocate separate time for voice therapy, and there were no space constraints, which means that accessibility to treatment was increased. In Korea, telepractice was initially adopted to eliminate the risk of COVID-19 infection, although once such practice was implemented, time and cost savings and greater access to treatment were viewed positively. From the patient’s perspective, satisfaction levels were high since vocal improvement could be achieved without the effort required to take part in face-to-face treatment. It is important to emphasize the elimination of potential viral infection and increased treatment access to promote the implementation of telepractice.
Secondly, all participants reported efficient time management as an advantage of voice therapy using telepractice, and additionally, Participant B indicated a positive evaluation of the reduced risk of COVID-19 spread. Participant C indicated that it was easier to concentrate since treatment was carried out in a comfortable place, consistent with reports in a study on voice therapy using telepractice for children [
10]. During voice therapy for children, the guardian must watch from behind or observe from a distance, but with voice therapy using telepractice, the child can participate in the treatment together with his or her guardian at home. This can naturally build rapport between the therapist and the child and his or her guardian, while the child can comfortably take part in the treatment. Moreover, because treatment takes place at home, the treatment contents may be accepted more readily, and the transition to daily life may be easier.
However, technical problems were mentioned as a disadvantage of voice therapy using telepractice. The participants reported the audio and video not being in sync, or the audio cutting off or fading at times, which are the same problems encountered in other countries where telepractice is more prevalent [
3]. At times, the participants had to reconnect after losing their internet connection during treatment, or sessions had to be cancelled due to difficulties with reconnection. It was suggested that an appropriate level of technical expertise is required to address such issues and that guidelines for telepractice need to be established. To resolve such technical difficulties, SLPs must coordinate with experts, and the participation of academic societies or associations for technical research and development should also be considered.
Another disadvantage mentioned was that there were parts that were difficult to understand within the treatment contents. Voice therapy using telepractice involves the exchange of information through the screen of the device used by each person. Generally, only auditory and visual cues are provided, but there are times when additional senses are required. Participant B expressed difficulty with sustained vocalization through abdominal breathing. Although the therapist explained how much the stomach should be expanded when inhaling and what physical changes are required when exhaling, it was not easy to perform the task. If the task was performed after personally feeling and comparing the physical changes in the other person, the treatment content may have been easier to understand. During telepractice, the therapist must provide accurate and detailed information to the patient, while the patients must try their best to accept such information. In addition, it is believed that the further development of treatment content and other related contents could be helpful in learning and generalizing the treatment content.
Thirdly, the areas for improvement of voice therapy using telepractice shared the same context as the technical limitations mentioned as the disadvantages of voice therapy using telepractice. In addition to technology development, institutional measures regarding telepractice must be established at the national level to promote the expansion of telepractice and change the perception of patients and therapists who use telepractice. Such actions could lead to universal acceptance of telepractice, which could naturally expedite the development of related technologies.
Fourthly, all participants indicated that they intend to participate in future telepractice, if given the opportunity. They mentioned prevention of concerns for potential COVID-19 infection and efficient time management. When vocal evaluations were classified according to the risk of exposure to COVID-19, self-evaluation by the patient or therapy using telepractice were viewed as low risk, while EGG or acoustic evaluation while wearing a mask was viewed as moderate risk, and aerodynamic evaluation was viewed as high risk [
8]. It was reported that vocal evaluation must take place in the face-to-face setting since such evaluation is difficult to perform by telepractice, but voice therapy should be performed by telepractice to avoid the risk of infection. Moreover, because face-to-face treatment involves both the therapist and patient wearing a mask, there are limitations in relaying accurate information due to distorted pronunciation, while certain exercises, such as SOVTE, may be difficult to perform accurately [
14]. Accordingly, voice therapy using telepractice was emphasized as a method that can overcome such issues. As described above, voice therapy using telepractice represents the present-day situation and it could be considered a method of providing beneficial service during potential future epidemics.
Fifthly, the participants preferred voice therapy using telepractice over face-to-face voice therapy. If the study had used an alternating treatment design to compare voice therapy using telepractice and face-to-face voice therapy, more reliable results may have been obtained. However, the participants were skeptical about the effectiveness of voice therapy using telepractice before their participation but were satisfied upon completion. From this, it can be inferred that patients prefer voice therapy using telepractice over face-to-face voice therapy. The participants were much more satisfied than they had anticipated since they noticed vocal improvement during voice therapy using telepractice and were able to comfortably participate in the treatment at the location of their choice while also being able to use their time efficiently. In particular, Participant B mentioned that she would like to see voice therapy using telepractice become more popular, and thus, it would be valid to view telepractice not just as an alternative to face-to-face treatment but as an equivalent method of service delivery.
Based on the findings described above, the significance of the present study can be found in the fact that it was the first study to identify vocal improvement through voice therapy conducted by non-face-to-face videoconferencing by providing only auditory and visual cues, when the discipline of speech therapy requires various cues, including auditory, visual, and tactile cues. Certainly, there are other studies in Korea that have reported on vocal improvement through voice therapy using telepractice [
17,
18]. However, the previous studies reported vocal improvement after applying both telepractice and face-to-face methods. Therefore, it is difficult to accept their findings that improvement was solely the effect of voice therapy using telepractice. However, all treatment sessions in the present study were conducted by telepractice and confirmed the usefulness of voice therapy using telepractice through vocal improvement, which can be viewed as important research findings. Moreover, by conducting an interview-based qualitative analysis with the participants, in-depth examination was also possible. However, it is difficult to generalize the findings due to the small sample size. Moreover, if the effectiveness of telepractice was demonstrated through a comparative study with a control group, the study could have been more meaningful.
Furthermore, the study selected patients with hyperfunctional voice disorder who have vocal fold lesions. Accordingly, the size of the lesion, the symmetry during vocal fold adduction/abduction, and the vocal fold vibration pattern of each participant could have been checked, but such factors were not analyzed after the treatment. Presenting the results from the analysis of such factors together could have enhanced the understanding of the effects of voice therapy using telepractice.
It would be useful to conduct future case studies on the speech therapists who delivered telepractice in the present study. Considering that other studies have reported that therapists with more experience tend to be more conservative toward telepractice [
19] and that improvement in awareness among therapists is needed for the expansion of telepractice [
14], a more specific approach is possible to determine which parts need improvement and upgrading for the expansion of telepractice.
In this post-COVID-19 era, people are using telepractice for some sense of comfort from the threat of infection. It is hoped that the findings of the present study will contribute to changing the perception about telepractice and provide an opportunity for telepractice to be incorporated into our lives so that therapy using telepractice does not remain a second-best choice but is regarded as a service that both SLPs and patients request as their first choice. As our research is a pilot study, it has limitations in drawing definitive conclusions. Therefore, validation through studies with a larger sample size and more rigorous statistical analysis is necessary.