Introduction: Essential vocal tremor (EVT) is vocal tremor occurring in an individual diagnosed with essential tremor and is an action induced tremor that occurs during speech production. It causes fewer communication attempts, difficulty initiating and maintaining phonation, effortful speaking avoidance of social events trouble sustaining relationship leading to impair quality of life for such persons.
Aim of the study: The aim of present study was to find out the efficacy of voice therapy in persons with voice tremors which may be shown in improvement in acoustic analysis and quality of life measures.
Methodology: The study was conducted at ENT department of PGIMER, Chandigarh. Two subjects were included in the study having a complaint of vocal tremors. A 65-year-old male patient and a 68 -year old female patient both diagnosed with EVT The acoustic assessment was done using Dr. Speech software. Effect of voice disorder on quality of life was assessed using Voice Handicap Index. Measurements were repeated after completion of a voice therapy program with a frequency of twice a week for eight weeks. A combination of Laryngeal maneuvers, Relaxation exercises and Breathing exercises were used in voice therapy protocol.
Results and Discussion: Pre-therapy and post-therapy comparison shows improvement in the quality of life shown by reduction of VHI scores across three parameters (functional, physical and emotional) of VHI in both the patients. Acoustic parameters of voice also showed improvement in terms of shimmer and HNR in both the patients.
Conclusion: The voice therapy shows improvement in the quality of life as well as acoustic parameters of voice in this population. More research is required in this area to find out the efficacy of this therapy protocol on a larger population.
Keywords: Essential Voice Tremors; Acoustic measurements; Quality of life; Voice Handicap Index Essential vocal tremor (EVT)
Essential vocal tremor (EVT) is vocal tremor occurring in an individual diagnosed with essential tremor and is considered to be an action induced tremor that occurs during speech production [1,2]. EVT affects the aging populations most as it is neurogenic in origin,  and may be present in isolation or in association with other disorders such as with Parkinson's disease, amyotrophic lateral sclerosis, spinal muscular dystrophy, spasmodic dysphonia, and other types of essential tremor, such as those affecting the limbs or face . Vocal tremors are present in musculature isolated to or combined with the larynx , tongue , jaw , face , head , and respiratory system . Main symptoms of vocal tremors include rhythmic modulations of pitch and loudness causing a fluctuating in the amplitude and fundamental frequency of the voice. Vocal tremor modulation rates may range from3-12 Hz during sustained phonation . It causes fewer communication attempts, difficulty initiating and maintaining phonation, effortful speaking avoidance of social events trouble sustaining relationship leading to impair quality of life for such persons .
Vocal tremors result from a lesion in the extrapyramidal system or cerebellum, basal ganglia or thalamus . Damage in these areas may disturb motor functions and coordination of muscles involving at any level of the speech production mechanism. Managing options for vocal tremors include Pharmacological drugs , Alcohol , Botox , and Deep brain stimulation . Use of Voice Therapy - In literature, it has been reported that voice therapy techniques are generally ineffective in treating vocal tremor [4,14]. The need of study- An
effective technique of voice therapy is the required which can reduce tremors in patients with vocal tremors as well as may be effective in improving the quality of life in such patients.
a. Case 1: A 65-year-old male patient was referred from Neurology department with a complaint of EVT to the speech and hearing unit, PGIMER, Chandigarh with a complaint of tremors in voice. Tremors were seen more during initiation of the conversation and led to breathlessness sometimes. Tremors were present in the right hand while writing. Perceptual voice assessment was done, which showed that Pitch and loudness variations were affected.
b. Case 2: A 68-year-old female patient was referred from Neurology department with a complaint of EVT to speech and hearing unit PGIMER, Chandigarh with a complaint of tremors in voice. The voice quality was strained. Tremors were seen more during initiation of the conversation and led to breathlessness sometimes. On perceptual voice assessment pitch and loudness, variations were affected.
Both cases underwent perceptual, acoustic assessments. The acoustic assessment was done using Dr. Speech software. Effect of voice disorder on quality of life was assessed using Voice Handicap Index Jacobson et al. . Both patients were enrolled for voice therapy program with a frequency of twice a week for eight weeks.
A combination of Laryngeal maneuvers, Relaxation exercises (to reduce muscle tension in and around the head and neck region) and Breathing exercises were used.
Laryngeal lowering: Dromey et al.  found that low- pitch phonation reduced the amplitude rate of vocal tremor. They concluded that a lowered larynx may have contributed to relaxation and stability in the vocal system, resulting in the reduction of tremor severity. Laryngeal lowering was achieved using digital manipulation.
Yawn-sigh : In this technique, the larynx drops to a low position, the tongue is more forward, there is slight opening between the vocal folds, and pharynx is usually dilated. The patient is asked to perform a yawn followed by relaxed sigh which is combined with phonation.
Easy voice onset: It facilitates reduced effort during voicing onset and to promote increased airflow through the vocal folds to achieve a slightly breathier and softer voice quality than typically exhibited .
Anterior focus: It was used to improve the use of vocal tract resonance for voice projection. At first, whisper is used to repeat front of the mouth words followed by repetition of light voice .
Differential relaxation exercise: It involves sequentially increasing tension in each body part and then relaxing it starting with either the feet and working upward to the head and neck and vice versa .
Breathing exercise: Laryngeal lowering/vocal tract lengthening also can be achieved through increases in lung volume, which cause the diaphragm and the supporting respiratory musculature to stabilize and lower the larynx through a diaphragmatic tracheal pull Iwarsson & Sundberg  Iwarsson et al. . These exercises include the use of forceful inhalation and exhalation and abdominal breathing techniques. Acoustical analyses of voice, as well as VHI, were re-administered after completion of voice therapy.
Pre and post therapy comparison for Acoustical analysis as well as VHI measures are given in the Tables 1-4. In Case 1 acoustical analysis Table 1 shows improvement in terms of shimmer and HNR. There was a slight increase in the jitter (0.22 to 0.82). However, the value is within normal limits (<1.04%). While on VHI (Table 3) there is improvement across all three parameters i.e. functional, physiological and emotional. In Case 2 there was an improvement in all three parameters of the acoustic measures i.e. jitter, shimmer and HNR (Table 2). VHI shows improvement in all three parameters (Table 4).
Previous research has indicated that individuals with neurologically-based voice disorders, including EVT, often experience reduced quality of life . Reduced quality of life may be related to fewer communication attempts, difficulty initiating and maintaining phonation, effortful speaking avoidance of social events trouble sustaining relationships . In this study also persons with vocal tremors reported reduced quality of life as shown by a high score on VHI in both the subjects.
Pre-therapy and post-therapy comparison of VHI shows reduction in scores in all three parameters i.e. functional, physical and emotional in both the patients indicating an improvement of the quality of life in both the patients. Pre and post therapy comparison of acoustical analysis of voice also showed improvement in shimmer and HNR measures in both the patients. In case 1 there is a slight increase in jitter post therapy (from 0.22 to 0.82). However, the value is within normal limits only. Thus a combination of relaxation exercises, laryngeal lowering, and breathing exercise are effective in improvement in acoustical parameters as well as an increase in quality of life in persons with vocal tremors.
The study highlighted the efficacy of voice therapy in persons with vocal tremors. The voice therapy shows improvement in the quality of life as well as acoustic parameters of voice in this population. More research is required in this area to find out the efficacy of this therapy protocol on a larger population.