Video Asylum

Posted by David Aiken (A) on October 22, 2007 at 13:42:42

In Reply to: RE: Except that posted by DavidLD on October 22, 2007 at 06:29:21

I used to work in occupational health and safety and hearing protection is an issue in that field.

There are standards for occupational noise exposure which are intended to limit the risk of hearing damage. Here in Australia those standards are based on a maximum daily exposure (8 hours a day, 5 days a week) to a continuous level of 85 dBA. Varying levels need to be averaged.

Music and soundtracks do not have continuous uniform sound levels. Brief exposures to loud sounds, ie sounds of the duration of a cannon shot, aren't going to add much to actual exposure levels when 8 hour averaging is done. There is a problem with impulse noise like actual cannon shots but I wonder how close to reproducing genuine impulse noise a speaker system would go. Headphones would probably go closer due to the lower mass of the diaphragm, especially with sealed headphones, so I would think that caution would be needed with such sounds but otherwise the hearing protection picture with headphones is not going to be significantly different to listening with speakers. It's all going to depend on levels and time spent listening. If you listen at the same actual volume levels measured in dB at the ear, not listening with the volume control set at the same point, then listening with headphones should be no more dangerous than listening with speakers.

As for dynamic range, that problem exists with both speakers and headphones and many AV receivers have dynamic compression options (eg "night mode") which can reduce the dynamic range but depending on how they operate they may tend to make speech less understandable. One can only try such options on a disc by disc basis to see if they help.

It's worth noting that the OP said he prefered using headphones because of the greater immediacy of the sound which does not necessarily mean greater volume levels. In fact there's no mention of volume levels in his post, so you're really jumping to a conclusion about the levels he's listening at and their potential hearing impact with no evidence at all when you respond that using headphones is an easy way to damage hearing. As with speakers it all depends on sound pressure levels and exposure times. Yes, you can damage your hearing with headphones but you can damage it also with speakers. Do you tell anyone who says they listen to movie soundtracks using speakers that "this is a great way to damage your hearing at an early age"?

Headphones can be used safely as can speakers. Both can also be used unsafely. Apart from the possible impulse noise issue, movies like "Master and Commander" are going to be no more dangerous on headphones than they are on speakers when listened to at the same volume levels.


David Aiken