A 2003 study published in Clinical Otolaryngology, found that a cotton ball saturated with petroleum jelly was more effective at keeping water out of the ear, easier to use, and more comfortable than wax plugs, foam plugs, EarGuard, Aquafit, or EarSeal.
As many have advised, including Jacques-Yves Cousteau, ear plugs are actually harmful to divers, especially SCUBA divers. Scuba divers breathe compressed air or other gas mixtures, at a pressure matching the water pressure. This pressure is also inside the ear, but not between the eardrum and the earplug, so the pressure behind the eardrum will often burst the eardrum. Skin divers have less pressure inside the ears, but they also have only atmospheric pressure in the outer ear canal.
Furthermore, they may be either disposable or nondisposable, with elastic and viscous ones generally being disposable or for use a relatively limited number of times, while solid ones generally may be regarded as nondisposable.
This kind of earplug protection is often worn by industrial workers who work within hearing distance of loud machinery for long periods, and is used by the British Ministry of Defence (MoD) for soldiers to use when firing weapons. Earplugs are rated with "Noise Reduction Ratings" or NRRs (Single Number Ratings, or SNR, in the European Union), which provide a guide to the noise protection, in decibels, afforded by the device. Ratings usually spread between 26 and 33 decibels.
Most earplugs are elastic ones made of memory foam, that is typically rolled into a tightly compressed cylinder (without creases) by the wearer's fingers and then inserted in the ear canal. Once released, the earplug expands until it seals the canal, blocking the sound vibrations that reach the eardrum. Other plugs simply push into the ear canal without being rolled first. Sometimes earplugs are connected with a cord to keep them together when not in use. Other common material bases for earplugs are viscous wax or silicone.
Other devices that provide hearing protection include electronic devices worn around and/or in the ear, designed to cancel out the loud noise of a gunshot, while possibly amplifying quieter sounds to normal levels. While rich in features, these electronic devices carry a price over one hundred times their foam counterparts.
Since they reduce the sound volume, earplugs are often used to help prevent hearing loss and tinnitus (ringing of the ears), amongst other ailments.
Musicians who perform music styles noted for their loud nature, especially rock music, often wear earplugs to prevent their own performances from damaging their hearing. Musician earplugs are designed to attenuate sounds evenly across the audio band and thus do not affect the user's perception of bass and treble levels. These are commonly used by musicians and technicians both in the studio and in concert to avoid overexposure to high volume levels whilst providing a good balance over the frequency range.
They generally achieve this by incorporating a tiny diaphragm to reduce low frequencies, together with absorbant or damping material for high frequencies, and so can be quite costly, being intended for constant re-use unlike simple earplugs which are disposable. These earplugs usually give an attenuation of only about 20dB and are not intended for protection from very high noise levels (>105 dB).
Some musicians earplugs are custom-made for the individual listener. An audiologist administers a hearing test and makes molds of the ear. A company then makes a custom ear-piece into which different attenuator capsules can be inserted. These different capsules will provide different levels of attenuation, usually 9, 15, and 25dB. These types of earplugs will provide the flattest attenuation and the truest isolation from outside noise, as they fit firmly into the individuals ears. They also provide much better protection from very high noise levels. This type of plug is quite popular amongst audio engineers who can safely listen to loud mixes at for extended periods.
In other activities, hobby motorcyclists and skiiers may also choose to use decibel reduction earplugs, to compensate for the ongoing noise of the wind against their head or helmet.
To determine the comfort of earplugs used for sleeping, it is important to try it on while actually lying down. The pressure on the ear between the head and pillow may cause a significant reduction in comfortableness. Furthermore, just tilting the head back or to the side causes significant anatomical changes in the ear canal, mostly a reduction of the ear canal diameter, which may cause less comfortableness if the earplug is too large.
Nevertheless, prolonged or frequently repeated use of ear plugs have the following health risks, in addition to the short term health risks:
Pressure and flight earplug molds are less common, as they are typically not used as long as other earplugs, and are therefore less in demand.
For best results they are molded in the ear while in the position that they will be used. For instance, if they are to be used for sleeping then they should be molded in the ear while lying down, as it causes significant changes to the form of the ear canal, mostly a reduction of the diameter, which may cause less comfortableness if the earplug is made too large.