The first article, without references, is a mixed bag. The hearing conservation guidelines cited are public-domain information and they apply to workers who are exposed to loud sounds five days a week, every week for a lifetime. They do NOT prevent hearing loss. The criteria by which these exposure levels and times were developed allow for hearing loss, but attempt to preserve enough that, at the end of a working career, normal conversational speech at 1 m distance is possible. Hi-fi hearing is long gone.
The workers engaged in such a hearing conservation program need to be tested on day one, so that lawyers have some defense if unexpected hearing loss is claimed later in their careers or tours of duty. It is considered acceptable for hearing loss to accumulate up to 25 dB in both ears at the 1kHz, 2kHz and 3 kHz audiometric frequencies. This means that one's dynamic range has been reduced by those amounts!. Small sounds are gone. In practical terms this translates to a loss of about 10% understanding of entire sentences, about 50% misunderstanding of monosyllabic “PB” words (words that are ambiguous because of similar sounding consonants) during conversation at normal voice levels, in the quiet, with persons one meter apart (Kryter, JASA 1973). And this is considered to be an acceptable situation −“normal” hearing. Further losses from 25 to 40 dB are described as “slight”. Really? For whom?
This is what your friendly audiologist is concerned with, not the ability to hear the finer details of music.
Hearing damage can occur as a result of many normal recreational or domestic activities like shooting, carpentry, mowing the lawn, chain-sawing, listening to personal music systems and so on. Power tools are noisy, kitchen blenders are noisy, and impact sounds like driving nails can generate very high momentary sound levels. Playing in a band, even a symphony orchestra, can be hazardous. Going to movies, rock concerts, and discos must be factored in. Over time it all adds up, and the cumulative effect is hearing loss, the amount depending on the sound levels and the exposure times. – it even has a name: “sociocusis” to differentiate it from occupational hearing loss. It is not practical to track the noise exposure resulting from casual activities like these so it is difficult to be dogmatic about what is or is not “safe”. The notable exceptions are extremely high sound levels produced by nearby guns, explosions, jet and rocket engines, etc. A single exposure to these sounds can produce permanent damage. However, not to be forgotten is that these accumulated exposures add to any occupational noise exposures.
So it is not new knowledge to say that presbyacusis (the statistical average hearing loss as a function of age) is not due to age. That, to be kind, is obvious. It is understandable that men experience higher losses than women - who has the noisy hobbies? Decades ago some scientists visited a tribe in Africa that lived a very quiet life. Their hearing was remarkable, and they could converse over large distances outdoors in near mumbles. So, if one grows old in a quiet environment it is highly probable that good hearing will be sustained over many years. However, that is not how we live our lives, and to accumulated damage as a result of noise exposure, one must add damage from ototoxic drugs, including NSAIDs, over the counter pain and inflammation medications (naprosin sodium/Aleve did it to me). Some prescription drugs are as damaging as a nearby gunshot. Instant, permanent, loss.
New data relate to our binaural hearing processes that allow us to separate multiple sounds in a complex environment, and to separate the sound source from reflections in a room. The findings indicate that these capabilities can be degraded without any change in our audiometric thresholds. This is disturbing.
Nothing is forever, so do what you can - musician's earplugs are highly recommended - while you can.
