Presbycusis
Encyclopedia
Presbycusis, or age-related hearing loss, is the cumulative effect of aging on hearing
. Also known as presbyacusis, it is defined as a progressive bilateral symmetrical age-related sensorineural hearing loss. The hearing loss is most marked at higher frequencies. Hearing loss that accumulates with age but is caused by factors other than normal aging is not presbycusis, although differentiating the individual effects of multiple causes of hearing loss can be difficult.
, whether at work or in leisure time (shooting, music, etc). This is Noise-induced hearing loss (NIHL) and is distinct from presbycusis.
Over time, the detection of high-pitched sounds becomes more difficult, and speech perception is affected, particularly of sibilants and fricatives. Both ears tend to be affected.
and giant stereociliary degeneration.
), and the development of a cell phone ringtone, Teen Buzz, for students to use in school, that many older instructors are unable to hear. In September 2006 this technique was used to make a dance track called 'Buzzin'. The track had two melodies, one that everyone could hear and one that only younger people could hear.
Hearing (sense)
Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses...
. Also known as presbyacusis, it is defined as a progressive bilateral symmetrical age-related sensorineural hearing loss. The hearing loss is most marked at higher frequencies. Hearing loss that accumulates with age but is caused by factors other than normal aging is not presbycusis, although differentiating the individual effects of multiple causes of hearing loss can be difficult.
Presentation
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 frequently 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 noiseNoise health effects
Noise health effects are the health consequences of elevated sound levels. Elevated workplace or other noise can cause hearing impairment, hypertension, ischemic heart disease, annoyance and sleep disturbance. Changes in the immune system and birth defects have been attributed to noise exposure...
, whether at work or in leisure time (shooting, music, etc). This is Noise-induced hearing loss (NIHL) and is distinct from presbycusis.
Over time, the detection of high-pitched sounds becomes more difficult, and speech perception is affected, particularly of sibilants and fricatives. Both ears tend to be affected.
Pathophysiology
Examples of microscopic changes seen in this condition are hair cell degeneration of the cochleaCochlea
The cochlea is the auditory portion of the inner ear. It is a spiral-shaped cavity in the bony labyrinth, making 2.5 turns around its axis, the modiolus....
and giant stereociliary degeneration.
Causes
Factors that can cause hearing loss, which can be difficult to distingish or separate from presbycusis, include:- HeredityHeredityHeredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve...
: Features like early aging of the cochlea and susceptibility of the cochlea for drug insults are genetically determined. - AtherosclerosisAtherosclerosisAtherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
: May diminish vascularity of the cochlea, thereby reducing its oxygen supply. - Dietary habits: Increased intake of saturated fatSaturated fatSaturated fat is fat that consists of triglycerides containing only saturated fatty acids. Saturated fatty acids have no double bonds between the individual carbon atoms of the fatty acid chain. That is, the chain of carbon atoms is fully "saturated" with hydrogen atoms...
may accelerate atherosclerotic changes in old age. - Diabetes: May cause vasculitis and endothelial proliferation in the blood vessels of the cochlea, thereby reducing its blood supply.
- Noise trauma: Exposure to loud noiseNoise pollutionNoise pollution is excessive, displeasing human, animal or machine-created environmental noise that disrupts the activity or balance of human or animal life...
/musicLoud musicThe term loud music is often used to refer to music that is played at a volume that disturbs others, such as neighbors or bystanders, who do not wish to hear the music, or that is otherwise viewed as a nuisance to the public...
on a continuing basis stresses the already hypoxic cochlea, hastening the presbycusis. - SmokingSmokingSmoking is a practice in which a substance, most commonly tobacco or cannabis, is burned and the smoke is tasted or inhaled. This is primarily practised as a route of administration for recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them...
: Is postulated to accentuate atherosclerotic changes in blood vessels aggravating presbycusis. - HypertensionHypertensionHypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
: Causes potent vascular changes, like reduction in blood supply to the cochlea, thereby aggravating presbycusis. - Ototoxic drugsOtotoxicityOtotoxicity is damage to the ear , specifically the cochlea or auditory nerve and sometimes the vestibular system, by a toxin. It is commonly medication-induced; ototoxic drugs include antibiotics such as the aminoglycoside gentamicin, loop diuretics such as furosemide, and platinum-based...
: Ingestion of ototoxic drugs like aspirinAspirinAspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
may hasten the process of presbycusis.
Cultural aspects
Recently, the ability of young people to hear high frequency tones that are inaudible to others over 25 or so has led to the development of technologies to stop younger people from loitering near British shops (The MosquitoThe Mosquito
The Mosquito or Mosquito alarm is an electronic device, used to deter loitering by young people, which emits a sound with a very high frequency...
), and the development of a cell phone ringtone, Teen Buzz, for students to use in school, that many older instructors are unable to hear. In September 2006 this technique was used to make a dance track called 'Buzzin'. The track had two melodies, one that everyone could hear and one that only younger people could hear.
See also
- Hearing rangeHearing rangeFor more detail on human hearing see Audiogram, Equal loudness contours and Hearing impairment.Hearing range usually describes the range of frequencies that can be heard by an animal or human, though it can also refer to the range of levels...
- Absolute threshold of hearingAbsolute threshold of hearingThe absolute threshold of hearing is the minimum sound level of a pure tone that an average ear with normal hearing can hear with no other sound present. The absolute threshold relates to the sound that can just be heard by the organism...
- The MosquitoThe MosquitoThe Mosquito or Mosquito alarm is an electronic device, used to deter loitering by young people, which emits a sound with a very high frequency...
- PresbyopiaPresbyopiaPresbyopia is a condition where the eye exhibits a progressively diminished ability to focus on near objects with age. Presbyopia’s exact mechanisms are not known with certainty; the research evidence most strongly supports a loss of elasticity of the crystalline lens, although changes in the...