When a patient with voice disorder and hoarseness refers to speech therapy, and the speech therapist performs regular and continuous evaluations to diagnose the causes of the patient's hoarse voice, which is not limited to the first meeting of the patient with the speech therapist. Voice evaluation is the first step in the treatment of hoarseness. The otolaryngologist may perform a voice evaluation before and after the full examination, therefore the speech therapist examines the results of the otolaryngologist's evaluation to set up a treatment plan, although the medical diagnosis of laryngeal disease is the responsibility of the otolaryngologist, but the voice diagnosis and analysis of the acoustic, perceptual and physiological aspects of the voice and the treatment of hoarseness are the responsibility of the speech therapist. When do we need sound therapy? Any abnormality in voice quality that affects speech and causes changes in various aspects of voice such as pitch, loudness, hoarseness, breathiness, violence and overall voice quality is included in the voice therapy screening test. Some people with voice disorders and hoarseness, for example, are people who do not speak loud enough or those whose voice pitch is abnormal and speak loudly, and it seems that the causes are functional and do not need a doctor's evaluation. Patients with problems in voice quality and resonance generally need to be examined by an otolaryngologist for the effectiveness of the speech therapy treatment program. Voice therapy largely depends on the extent to which the speech therapist can correctly diagnose the causes of hoarseness and related disorders. What is sound therapy? Voice therapy includes tests that evaluate voice from different aspects. **The most important parts of voice evaluation in voice therapy are:** #### Patient history taking Evaluation of pitch and frequency of sound Assessment of loudness and intensity of sound Quality analysis of sound wave complexity Analysis of the otolaryngologist's report The ability to choose and provide patient-specific treatment methods Detecting the loss of exhaled air or measuring the air flow rate Video endoscopy data analysis Observe the patient's behavior Analysis of data from electroglottography Some types of hoarseness develop gradually, and hoarseness is gradual due to the variable situations in which patients are placed, and sometimes hoarseness is due to mental stress, stress, or after fatigue. Sometimes hoarseness is the only initial sign of a progressive neurological disease. Here, there is a long history of hoarseness, and the medical diagnosis does not indicate the presence of a specific disease, but when we refer the patient to a neurologist in the clinic, we see that the initial symptoms of progressive paralysis are Supranuclear has been diagnosed. Sound therapy, like other forms of compensatory therapy, will be more successful in patients who are motivated to overcome their problems. In speech therapy and sound therapy, the aspects of voice are evaluated from seven aspects, which are: **height, loudness, quality, resonance of horns, mouth resonance, speed of speech and changeability of the song** are examined and the production of each of the aspects of voice is examined in three situations, which **are:** 1. Dialogue 2. During the game 3. Reading the text In the clinic, people suffering from voice disorders and hoarseness should be evaluated for hearing. Hearing loss has a profound effect on the pressure below the eardrum, the vibration of the vocal folds, the reverberation and loudness of speech, and the hearing status of the patient should be checked. Before starting the treatment of hoarseness, the audiometer should evaluate the patient. Evaluation of the mouth, facial organs, tongue, teeth, hard palate, soft palate, pharynx, nasal cavities and how the teeth grow is important in evaluating the voice. In general, the larynx and respiratory system should be fully evaluated. **What is the larynx? The larynx and its function in the vocal cords and how to produce sound** last word Viewing the vocal tract and imaging through endoscopy are among the methods that are used for extensive examination of the vocal tract and organs of the larynx, palate, and pharynx. Many hoarseness is the result of subtle abnormalities in the physiology of the larynx, and the way the vocal cords approach each other is wrong, and the vocal cords are in the position of the tongue or in the pharynx or in excessive stiffness. As the flow of exhaled air passes through the middle of the closed throat, the vocal cords are forced to produce sound, measuring breathing and evaluating it is an essential part of voice therapy.