Pulsatile tinnitus is yet another of the typical symptoms of SCDS and is caused by the gap in the dehiscent bone allowing the normal pulse-related pressure changes within the cranial cavity to enter the inner ear abnormally. These pressure change thus affect the sound of the tinnitus which will be perceived as containing a pulse-synchronized "wave" or "blip" which patients describe as a "swooshing" sound or as being like the chirrup of a cricket or grasshopper. Brain fog and fatigue are both common SCDS symptoms and are caused by the brain having to spend an unusual amount of its energy on the simple act of keeping the body in a state of equilibrium when it is constantly receiving confusing signals from the dysfunctional semicircular canal. Headache and migraine are also often mentioned by patients showing other symptoms of SCDS due to the body overcompensating for poor hearing in the affected ear by tensing up nearby parts of the face, head, and neck and using them as almost a secondary eardrum. Causes
According to current research, in approximately 2.5% of the general population the bones of the head develop to only 60–70% of their normal thickness in the months following birth. This genetic predisposition may explain why the section of temporal bone separating the superior semicircular canal from the cranial cavity, normally 0.8 mm thick, shows a thickness of only 0.5 mm, making it more fragile and susceptible to damage through physical head trauma or from slow erosion.
Superior semicircular canal dehiscence syndrome  is a set of hearing and balance symptoms, related to a rare medical condition of the inner ear, known as superior canal dehiscence. The symptoms are caused by a thinning or complete absence of the part of the temporal bone overlying the superior semicircular canal of the vestibular system. There is evidence that this rare defect, or susceptibility, is congenital. There are also numerous cases of symptoms arising after physical trauma to the head. It was first described in 1998 by Lloyd B. Minor of Johns Hopkins University in Baltimore. Symptoms
Superior canal dehiscence (SCD) can affect both hearing and balance to different extents in different people.Symptoms of SCDS include:

Autophony – persons own speech or other self-generated noises (e.g. heartbeat, eye movements, creaking joints, chewing) are heard unusually loudly in the affected ear
Dizziness/ vertigo/ chronic disequilibrium caused by the dysfunction of the superior semicircular canal
Tullio phenomenon – sound-induced vertigo, disequilibrium or dizziness, nystagmus and oscillopsia
Pulse-synchronous oscillopsia
Hyperacusis – the over-sensitivity to sound
Low-frequency conductive hearing loss
A feeling of fullness in the affected ear
Pulsatile tinnitus
Brain fog
Fatigue
Headache/migraine
Tinnitus – high pitched ringing in the ear

Symptoms in detail
SCDS-related autophony differs greatly in quality and range from the more common form which results from an open, or patulous Eustachian tube through which sufferers of this disorder hear the sound of their own voice and breathing. In contrast, patients with SCDS-related autophony report hearing their own voice as a disturbingly loud and distorted "kazoo-like" sound deep inside the head as if relayed through "a cracked loudspeaker."