Tinnitus that's continuous, steady, and high-pitched (the most common type) generally indicates a problem in the auditory system and requires hearing tests conducted by an audiologist. Pulsatile tinnitus calls for a medical evaluation, especially if the noise is frequent or constant. MRI or CT imaging may be needed to check for a tumor or blood vessel abnormality.
To answer your question about NAC (N-acetyl-L-cysteine), I’ve seen little evidence suggesting that is effective for tinnitus. Instead – though the research is very limited – multiple anecdotal reports describe success with the herb ginkgo biloba. Try taking two tablets of standardized extract of ginkgo three times a day with meals (no more than a total dose of 240 mg a day). Ginkgo may work by increasing blood circulation to the head and neck. Give it at least a two-month trial. You might also explore cranial therapy, a gentle manipulative technique performed by osteopathic physicians. This approach seems to take the pressure or irritation off the auditory nerves. If high blood pressure is responsible for your tinnitus, try to get that under control through diet, exercise, and weight loss or medication if necessary.
In persons with pulsatile tinnitus, additional tests maybe proposed to study the blood vessels and to check the pressure inside the head. Gentle pressure on the neck can be performed to block the jugular vein but not the carotid artery. The Valsalva maneuver reduces venous return by increasing intrathoracic pressure. If there is a venous hum, this usually abates or improves markedly. If the pulsation is arterial, these tests have no effect.
Exposure to loud noise: Loud noise exposure is a very common cause of tinnitus today, and it often damages hearing as well. Unfortunately, many people are unconcerned about the harmful effects of excessively loud noise from firearms, high intensity music, or other sources. Twenty-six million American adults have suffered noise-induced hearing loss, according to the NIDCD.

It is possible that the most common cause of pulsatile tinnitus is sigmoid sinus diverticulum and dehiscence, which can be collectively referred to as sinus wall abnormalities or SSWA. The sigmoid sinus is a blood carrying channel on the side of the brain that receives blood from veins within the brain. The blood eventually exits through the internal jugular vein. Sigmoid sinus diverticulum refers to the formation of small sac-like pouches (diverticula) that protrude through the wall of the sigmoid sinus into the mastoid bone behind the ear. Dehiscence refers to absence of part of the bone that surrounds the sigmoid sinus in the mastoid. It is unknown whether these conditions represent different parts of one disease process or spectrum, or whether they are two distinct conditions. These abnormalities cause pressure, blood flow, and noise changes within the sigmoid sinus, which ultimately results in pulsatile tinnitus. Narrowing of the blood vessel that leads into the sigmoid sinus, known as the transverse sinus, has also been associated with pulsatile tinnitus.
Tinnitus can occur as a sleep disorder - -this is called the "exploding head syndrome". This most often occurs while falling asleep or waking up. It is a tremendously loud noise. Some theorize that this syndrome is due to a brief seizure in auditory cortex. It is not dangerous.(Green 2001; Palikh and Vaughn 2010). Logically, anticonvulsants might be useful for treatment.
We conducted a randomized, double-blind, placebo-controlled trial investigating the effects of the customized music-based sound therapy for reducing tinnitus. Participants (N = 50) who suffered from tinnitus were randomly allocated (with 1:1 ratio) to the treatment and placebo groups with assessments at baseline, 3, 6, and 12 months. The primary outcome was the differences in mean scores of the THI compared at four time intervals. Independent and paired samples t-tests were conducted to compare THI scores between and within groups, respectively.
A large, 2014 study of almost 14,000 people found obstructive sleep apnea was linked to significantly higher rates of hearing impairment and hearing loss. Scientists think one reason for this is changes to blood flow to the ear that result in inflammation. (We know that sleep apnea causes changes to circulation and weakens blood flow to some areas of the body, including the brain.) A related factor? People with sleep apnea are at greater risk for high blood pressure, and high blood pressure can exacerbate hearing loss, according to research.
Prevention involves avoiding loud noise.[2] If there is an underlying cause, treating it may lead to improvements.[3] Otherwise, typically, management involves talk therapy.[5] Sound generators or hearing aids may help some.[2] As of 2013, there were no effective medications.[3] It is common, affecting about 10–15% of people.[5] Most, however, tolerate it well, and it is a significant problem in only 1–2% of people.[5] The word tinnitus is from the Latin tinnīre which means "to ring".[3]
Some persons with severe TMJ (temporomandibular joint) arthritis have severe tinnitus. Generally these persons say that there is a "screeching" sound. This is another somatic tinnitus. TMJ is extremely common -- about 25% of the population. The exact prevalence of TMJ associated tinnitus is not established, but presumably it is rather high too. Having TMJ increases the odds that you have tinnitus too, by about a factor of 1.6-3.22 (Park and Moon, 2014; Lee et al, 2016). This is the a large risk factor for tinnitus, similar to the risk from hearing loss (see table above).
Ear canal obstructions, infections, injuries or surgeries. This can include ossicle dislocation within the ear that affects hearing or recurring ear infections (like swimmer’s ear) either in the outside or inside of the ear canal (otitis media or otitis externa). Other ear disorders tied to tinnitus include otosclerosis (causes changes to the bones inside the ears), tympanic membrane perforation or labrynthitis (chronic infections or viruses that attack tissue in the ears).
For some people, the jarring motion of brisk walking can produce what is called a seismic effect which causes movement in the small bones or contractions in the muscles of the middle ear space. You can experiment to find out if this is the cause by walking slowly and smoothly to see if the clicking is present. Then, try walking quickly and with a lot of motion to see if you hear the clicking. You can also test for the seismic effect by moving your head up and down quickly.