Treatments for hoarseness due to unilateral vocal fold paralysis (UVFP) include surgical treatment and conservative treatment, and conservative treatment includes voice therapy. If laryngeal stroboscopy reveals that the glottal gap is mild during phonation, voice therapy is indicated. Voice therapy is also indicated when patients wish to improve their voice further after voice improvement surgery, and when laryngeal findings and voice evaluation indicate that voice therapy is effective.
In the past, hard attack and pushing method were performed as voice therapy techniques for UVFP, but today they are no longer actively used because hypertonic phonation may occur after treatment. We have actively used a modified version of vocal function exercises (VFE) to treat UVFP. One positive effect of VFE (modified method) to treat UVFP is that further improvement in vocal function can be expected by improving the regularity of vocal cord vibration by increasing the muscle strength of the laryngeal muscles and adjusting the mutual balance of the laryngeal muscles.

The singing voice derives from expiratory regulation, laryngeal regulation, and vocal tract morphology regulation, and is produced through their integration. The ideal singing voice differs mainly according to genre, language, and acoustic environment, and this diversity must be understood. For this purpose, it is necessary to evaluate the vocal status based on the mechanisms of vocalization. I devised a three-step process to consistently and objectively assess the three elements of vocalization.
Step 1: I devised a simple respiratory evaluation method, named the Saida method, based on the strain gauge system and MRI, to classify into five categories.
Step 2: Using a high-speed camera and electroglottogram (EGG), I clarified the characteristics of four vocal fold vibration patterns (vocal fry, modal, falsetto, and whistle voice), and developed a Voice range map based on voice pitch and expiratory flow rate. The relationships between vibratory patterns were also clarified.
Step 3: I developed a Tone color map based on sound source characteristics and vocal tract characteristics. This corresponds to the auditory impression, and use of the map enables knowledge of the vocal tract morphology and what laryngeal adjustment to perform for the desired tone color, permitting free voice design.
Following these three steps produces a blueprint of the voice which is helpful in the performance of voice surgery and voice therapy.

This paper describes Music Therapy Voice Protocol (MTVP), a rehabilitative application of singing to improve vocal/speech functions. Developed for patients with Parkinson's disease (PD), this intervention method focuses on the motor effects of singing. Professional singers' excellent skills in controlling their diaphragm movement, visualized by real-time MRI, indicate that singing is a "sport" with dynamic use of respiratory organs and trunk muscles. Senior singers with years of singing experience showed higher vocal functioning than non-singer seniors, which implies the merit of a years-long singing habit. The MTVP consists of a series of exercises including a physical warm-up, respiratory/phonatory/articulation exercises, reading exercises, and the singing of preferred songs. Music therapists aim to improve vocal/speech functions of PD patients along with considering the psychological impacts singing has on them.

The origin and evolution of spoken language is the last frontier in studies of human evolution. Humans use a series of phonemes even in a single exhalation for language communication, whereas nonhuman primates utilize volume, pitch, and length of a single vocal sound in a single exhalation for their vocal communication. Voices are generated through the resonance of the vocal tract with a vocal source that is usually generated by vibrations of the vocal folds. The human vocal tract consists of a long pharyngeal cavity and a short oral cavity compared to nonhuman primates, and this feature allows us to modify the volumetric shape of the vocal tract sequentially to generate the phonemes intended. On the other hand, our simple vocal fold, which has lost a vocal membrane, allows us to maintain its vibration stable. Such a vocal source underlies our faculty to correctly convey phoneme changes. Monkeys have a static vocal tract, and although the vocal membrane improves the efficiency of source generation, it impairs its stability. Our spoken language probably has arisen as a form of communication that enables the sender to stably deliver a series of phonemes to a receiver face-to-face.

There are currently no internationally standardized diagnostic criteria for the diagnosis of spasmodic dysphonia. In Japan, diagnostic criteria and severity classifications for spasmodic dysphonia were established in 2018. Currently, we are working on validation and revision of these diagnostic criteria. According to Japanese diagnostic criteria, stuttering is one of the diseases that should be differentiated from spasmodic dysphonia. In this paper, we review the literature on the speech symptoms and epidemiology of spasmodic dysphonia and stuttering, and summarize the key points in their differential diagnosis.

We report the case of a 7-year-old left-handed boy with moderate hearing loss who, based on his speech characteristics, was suspected to have phonological impairment. Although the child had been examined at several facilities due to his language delay, a definitive diagnosis, including hearing loss, had not been reached. Therefore, in addition to a thorough examination of his hearing, we administered cognitive function tests, including a phonological awareness test, and performed diagnostic imaging, including SPECT and MRI. Results indicated that the child had both moderate hearing loss and several features of specific language impairment (SLI), leading to a diagnosis of disproportionate language impairment (DLI). He simultaneously underwent phonological-language training as well as hearing intervention, and his language ability improved rapidly. The diagnosis of hearing loss is important, but the child's symptoms in this case also required a detailed examination of language and cognitive functions, and appropriate support was necessary.