Foam earplugs will block out all or most external sound and are useful when using: electric power tools, noisy garden equipment etc. They are not ideal for reducing external sound and one should use "noise reducing" earplugs for this purpose. If foam earplugs are used on a regular basis to suppress normal everyday sounds, it is likely the auditory system will become more sensitive to sound, making it hypersensitive and the risk of hypercusis becoming worse.
Similarly, noise reducing earplugs have their use. However, if they are used too regualarly the auditory system can be affected in a similar way as discribed above. One of the best ways to desensitize the auditory system, is to use sound enrichment and go out daily for a walk to get used to normal everyday sounds. This helps to close down the auditory receptors or gateways that have opened up in the brain due to noise trauma. Anyone with noise induced tinnitus with or without hyperacusis, will delay healing of the auditory system and the habitation process by overusing earplugs to suppress normal everyday sounds.
Michael