Presentation
Primary symptoms:

sounds or speech becoming dull, muffled or attenuated
need for increased volume on television, radio, music and other audio sources
difficulty using the telephone
loss of directionality of sound
difficulty understanding speech, especially women and children
difficulty in speech discrimination against background noise (cocktail party effect)Secondary symptoms:

hyperacusis, heightened sensitivity to certain volumes and frequencies of sound, resulting from "recruitment"
tinnitus, ringing, buzzing, hissing or other sounds in the ear when no external sound is presentUsually occurs after age 50, but deterioration in hearing has been found to start very early, from about the age of 18 years. The ISO standard 7029 shows expected threshold changes due purely to age for carefully screened populations (i.e. excluding those with ear disease, noise exposure etc. ), based on a meta-analysis of published data. Age affects high frequencies more than low, and men more than women. One early consequence is that even young adults may lose the ability to hear very high frequency tones above 15 or 16 kHz. Despite this, age-related hearing loss may only become noticeable later in life. The effects of age can be exacerbated by exposure to environmental noise, whether at work or in leisure time (shooting, music, etc.). This is noise-induced hearing loss (NIHL) and is distinct from presbycusis. A second exacerbating factor is exposure to ototoxic drugs and chemicals. Over time, the detection of high-pitched sounds becomes more difficult, and speech perception is affected, particularly of sibilants and fricatives. Patients typically express a decreased ability to understand speech.
Examples of sociocusis-related stimuli are the continuous noises from traffic, home appliances, music, television, and radio. The accumulated exposure to these noises over many years can lead to a condition similar to pure presbycusis. Nosocusis
Nosocusis factors are those that can cause hearing loss, which are not noise-based and separate from pure presbycusis. They may include:
Ototoxic drugs: Ingestion of ototoxic drugs like aspirin may hasten the process of presbycusis. vascular degeneration
Atherosclerosis: May diminish vascularity of the cochlea, thereby reducing its oxygen supply. Dietary habits: Increased intake of saturated fat may accelerate atherosclerotic changes in old age. Smoking: Is postulated to accentuate atherosclerotic changes in blood vessels aggravating presbycusis. Diabetes: May cause vasculitis and endothelial proliferation in the blood vessels of the cochlea, thereby reducing its blood supply. Hypertension: causes potent vascular changes, like reduction in blood supply to the cochlea, thereby aggravating presbycusis.However, a recent study found that diabetes, atherosclerosis and hypertension had no correlation to presbycusis, suggesting that these are nosocusis (acquired hearing loss) factors, not intrinsic factors. Pathophysiology
Examples of microscopic changes seen in this condition are hair cell degeneration of the cochlea and giant stereociliary degeneration. There are four pathological phenotypes of presbycusis:

Sensory: characterised by degeneration of the organ of Corti, the sensory organ for hearing. Located within the scala media, it contains hair cells with stereocilia, which extend to the tectorial membrane. The organs outer hair cells play a significant role in the amplification of sound and is extremely sensitive to external and internal factors.