Noise-Induced Hearing Loss (NIHL): The patient's audiogram shows a significant notch at 4000 Hz, which is a common finding in NIHL. The symmetry of the hearing loss and the specific frequencies affected also support this diagnosis.

Ototoxicity: Certain medications or chemicals can cause hearing loss, particularly at high frequencies. The patient's history of exposure to such substances could support this diagnosis.
Genetic Hearing Loss: Some forms of genetic hearing loss can present in young adulthood, and the patient's family history may be relevant in supporting this diagnosis.
Middle Ear Pathology: Conditions such as otosclerosis or a middle ear effusion could cause a conductive hearing loss, but the patient's audiogram suggests a sensorineural hearing loss.

Acoustic Neuroma: Although rare, an acoustic neuroma can cause unilateral or asymmetric sensorineural hearing loss. It is essential to rule out this diagnosis due to its potential impact on the patient's health and treatment options.
Meniere's Disease: This condition can cause fluctuating sensorineural hearing loss, vertigo, and tinnitus. While the patient's audiogram does not show the typical low-frequency loss associated with Meniere's, it is crucial to consider this diagnosis due to its potential for significant impact on the patient's quality of life.
Infections such as Syphilis or Lyme Disease: These infections can cause hearing loss, and it is essential to rule them out due to their potential for serious health consequences if left untreated.

Usher Syndrome: A genetic disorder that causes combined hearing and vision loss, typically presenting in childhood or adolescence.
Pendred Syndrome: A genetic disorder that causes hearing loss and thyroid abnormalities, often associated with a specific type of hearing loss on audiogram.
Autoimmune Inner Ear Disease: A rare condition in which the immune system attacks the inner ear, causing hearing loss, vertigo, and tinnitus.