Tinnitus is a kind of sound that patients feel when there is no external sound source. It is reported that the global incidence of adult tinnitus is 10% to 15%, and 20% of these patients need clinical intervention [1]. The incidence of tinnitus in people over 60 years old is reported to be 14.5% in China. There are three reasons for the increase in tinnitus: the first is the deepening of social aging degree; the second is the impact of urban pollution, especially noise pollution; and the third is the extensive use of all kinds of vehicles. Accordingly, the tinnitus population who need intervention treatment increases.
Tinnitus itself is not a disease, but a symptom. It is the sound perception of the ear or head when these is no external sound. Its occurrence is the result of many factors, and sometimes it is the precursor of a disease. The incidence of tinnitus has gradually increased in recent years [2]. Studies have shown that tinnitus not only affects patients' language communication and sleep quality, but also causes anxiety, depression and even suicidal tendencies in patients with chronic tinnitus [3,4]. Tinnitus is one of the three most common complications in otology. The number of tinnitus patients is quite large, and the prevalence rate is usually 10%-15% [5].
In the course of this new product trial, a global COVID-19 outbreak. Going to the hospital for a follow-up is a greater risk of infection. In this case, the doctor is difficult to grasp the patient's condition, and timely adjustment of treatment program. Based on this, in the course of this experiment, we contact the relevant departments of the hospital to take measures to ensure that doctors can timely access to patients with tinnitus. To channel the patients' emotions in a proper way and reduce the negative impact of the epidemic on their emotions. So that all participants can maintain an optimistic attitude to receive treatment, to maximize the efficacy of the product.
Current common methods and analysis of tinnitus treatment
Causes and treatment of tinnitus
With the development of society and the acceleration of life rhythm, the incidence of tinnitus is increasing year by year. It seriously affects the people’s body, mind and life. According to survey study of Ma and Zhu (2009), 2.4% of the tinnitus patients would seek for hospital treatment [6]. Therefore, it is a pressing problem for the medical community to explore effective methods to prevent and treat tinnitus. Tinnitus is only a sensation, rather than sound hallucinations or illusions. At present, there is no evidence of visual perception about tinnitus in medicine. There are different opinions on tinnitus’s pathogenic site and its lesion physiological changes. Experts generally believe that tinnitus is not an independent disease [7]. Tinnitus can be caused by the lesions in any part of the auditory system, meanwhile, it sometimes can also be a concomitant symptom of systemic diseases. The etiology and influencing factors of tinnitus are diverse, so it is difficult to find its exact cause [8].
The pathogenesis of tinnitus is complex and related to many diseases[9]. Moreover, due to the unclear mechanism, there is still a lack of specific treatment methods and drugs at this stage. As a result, the treatment process of tinnitus is also diversified. From the perspective of medicine, tinnitus treatment commonly focuses on the physiological treatment, such as surgical removal of acoustic nerve tumors, including drug therapy [10] and surgery, so as to achieve the purpose of treating tinnitus. But in the field of audiology, another more commonly used method to treat tinnitus called "tinnitus management", which focuses on the improvement of the overall condition, i.e. physiological and psychological condition after the treatment[11], including counseling, cognitive behavioral therapy[12], acclimation therapy, application of hearing aids, tinnitus masks and auxiliary devices, etc. In conclusion, there are two principles for the treatment of tinnitus at this stage. The first is etiological treatment, which means to treat the protopathy of the tinnitus. After the treatment of the protopathy, there still will be long-term severe tinnitus. The cause of this long-term tinnitus is unclear, but it will remain exist seriously for quite a long time. The second is symptomatic treatment, including tinnitus retraining therapy, masking therapy, music therapy, relaxation therapy and so on.
Sound-based therapy: tinnitus retraining therapy and masking therapy
There are two recognized and widely used methods in sound therapy of tinnitus, namely tinnitus retraining therapy and tinnitus masking therapy. The former is widely used in the world, while the latter is commonly used in some areas, such as China [13]. Tinnitus retraining therapy (TRT) is a therapy based on the tinnitus neurophysiological model. Its purpose is not to eliminate the production of sound, but to block the tinnitus-related sound signals (the activity of tinnitus-related neuron) transmitted from the auditory pathway to other brain systems, especially the limbic system and autonomic nervous system. Xu and Bu (2012) stated that tinnitus retraining therapy belongs to the incomplete masking therapy and proposed that masking the sound intensity cannot actually cover up tinnitus but coexist with tinnitus[14]. Through long-term retraining training (psychological adjustment, diversion of attention and sound therapy, etc.), the central sensitivity of the patients would reduce, which makes the patients adapt to the tinnitus. The method has been widely used in the treatment of tinnitus [15]. Jastreboff PJ (2013) believes that TRT is suitable for any type of tinnitus treatment [16].
The principle of tinnitus masking therapy is, making the tinnitus patient always in a circumstance of some small volume natural voice, rather than an absolutely quiet circumstance, by which the patient’s attention could divert from the tinnitus and the patient’s tension could relax. This therapy can also improve insomnia, depression, anxiety and other non-auditory problems in patients with severe tinnitus [17]. At present, masking therapy is widely used in clinical treatment of tinnitus patients in China. Masking therapy is also a physiological treatment. It is simple, safe, and with fewer adverse reactions. However, masking therapy can only work on a particular kind of tinnitus patients. Moreover, if the patients leave the masking, tinnitus will still occur. As thus, masking therapy cannot achieve the desired therapeutic effect.
There are three goals of using sound to treat tinnitus, no matter with tinnitus retraining therapy or masking therapy. Firstly, to reduce stress and tension caused by tinnitus. Secondly, to divert patients' attention from tinnitus by reducing the difference between tinnitus and ambient sound. Thirdly, to actively distract patient from the tinnitus. This study investigated the tinnitus rehabilitation technology used by different hearing aid manufacturers. Given Sonova in Switzerland and Audikang in Denmark as examples, the hearing aids of these companies adopted the traditional "masking" technology. The devices in fact cover up the tinnitus with a louder voice, in order to help the patients ignore the existence of tinnitus. This also exposed the limitations of masking technology. After a period of time, tinnitus often occurs again and produces a new round of tinnitus. At this time, patients often feel an even louder tinnitus than before (i.e. a "rebound"). Consequently, the patients need a higher decibel of sound to mask tinnitus, which can lead to repeated tinnitus symptoms, and even cause hear loss or other secondary damages to patients.
Emerging Application of music therapy in tinnitus treatment: From white noise to pink noise
Application of music therapy in tinnitus treatment
The methods of sound therapy for tinnitus includes not only tinnitus retraining therapy and masking therapy, but also music therapy. In recent years, with the change of medical model, people's psychological and social attributes have attracted more and more attention. Therefore, the great importance is gradually given to the music therapy. This therapy is considered to be creative, flexible, safe and effective. Music has a relaxing effect, so that patients can temporarily ignore the existence of tinnitus. This music therapy has been widely used in the world and its effect has been verified. Studies have shown that the brain dominates music activities, and many human emotions and behaviors are under the control of the right hemisphere [18]. Music plays a direct role on the right hemisphere of the brain, which can regulate human emotions and behaviors. This is an important basis for the principles of music therapy. Music therapy is a kind of therapy which takes music activities as the medium and influences the human body through the characteristics of music to help patients achieve the integration of physiology, psychology and emotion in the course of treatment, thus eliminating psychological obstacles and restoring or improving mental and physical health [19]. Zhou and Ma (2012) found that the relaxation training of music is very helpful to adjust the mentality of tinnitus patients [20].
Christoph et al. (2015) studied on the neurological basis of Heidelberg music model in the treatment of tinnitus[21]. Fifty patients with acute tinnitus were randomly divided into treatment group and control group. The treatment group was treated with Heidelberg music model. Before and after treatment, MRI and noise levels were measured and analyzed. The results showed that the structural gray matter in the precuneus, medial frontal lobe and auditory cortex of the treatment group was higher than that of the control group.
The limitations of current music therapy and the "pink noise"
Simple music therapy for tinnitus has been discussed for a long time in clinical research. The sound of beautiful external music can attract the patients' attention from the tinnitus and reduce patients’ perception of tinnitus. In this way, patients would temporarily ignore the tinnitus and gradually adapt to tinnitus. Recently, music therapy is playing an important role in tinnitus treatment. However, previous research also showed that if the patients listen to the same piece of music for a long term, their sensitivity of hearing will reduce, due to auditory fatigue. Furthermore, because the background noise of hearing equipment is uncontrolled, the patients are easy to get further hearing loss. Therefore, it is called for more efforts to spend on exploring other types of music that can also be used as the base note in the tinnitus treatment, with the similar or even better curative effect.
At present, in the treatment of tinnitus, most of the tones are based on "white noise". White noise refers to the sound in which the power of the frequency component is uniform in the whole audible range. As the human ear is sensitive to high frequency, this “white noise” sounds very noisy rustle. The white noise is recognized as an effective "sound cosmetic treatment" for nervous system diseases such as mental distraction, tinnitus, auditory hypersensitivity and hyperactivity disorder.
Referring to the latest findings in audiological research, we find that the frequency component power of pink noise mainly distributes in the middle and low frequency bands, which have better suppression function for tinnitus. Based on this, the semi-duplicated "pink noise" was used as the basic tone in this study, aiming to optimize the performance of tinnitus rehabilitation. On the other hand, from the perspective of waveform, pink noise is fractal. The audio data within a certain range has the same or similar energy. Fractal music is more effective than white noise in the treatment of tinnitus, which is also recognized by international audiologists. Meanwhile, pink noise can be used to simulate natural sounds such as waterfalls or rain. This kind of sound can soothe people's emotions and make people relax.