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This is similar to another post but not quite the same... At work, our ventilation system produces a constant low pitched sound - like a rumble - as well as the sound of air blowing through the vents. It's not very loud, we can certainly talk, even whisper to each other, but when it shuts off, it's like a huge weight off my shoulders. My ears don't really pop but there's sort of a slight "tingling" sensation - like when the blood starts flowing to a hand or foot that fell asleep. You can usually hear several people in the same room say "Ahhh" as in we are all glad the noise has stopped. I have worked in this location for over 10 years and in that time I have developed tinnitus which is probably attributed to a number of bad behaviors as a youth. But I was wondering if this constant noise could contribute to the decline in hearing? Also, that sense of relief when the noise stops makes me wonder if the constant noise adds to our stress levels?

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  • $\begingroup$ All unnecessary noise (noise pollution) causes some degree of stress; often one accommodated to it well. Clearly the noise in your office is loud enough that you find it stressful, as do others. Most times, the cause of tinnitus is unknown; noise can make it worse, however. You might want to try to protect your hearing at work? $\endgroup$ – anongoodnurse Nov 18 '14 at 23:23
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Basically you are asking: (1) does the low-pitch noise affect my hearing sensitivity; (2) has the noise aggravated hearing loss acquired earlier in life; (3) if the noise can induce stress and (4) if the noise may cause tinnitus (kind of a hidden question).

(1) Is the ventilator noise damaging?: Noise-induced hearing loss typically occurs at high sound levels. Occupational safe noise levels are set at around 85 dB SPL (Nat. Stand. Occupational Noise). This is comparable to listening to traffic on a busy road from 10 meters away for 8 hours/day for 5 days/week (see wiki on sound levels), or a diesel truck at 15 meters going 64 km/h. If you can still talk normally, the noise cannot be much more than 60 dB SPL, which is normal conversational level (see sound chart). So the ventilation noise is not bad for your ears as it is well below 85 dB SPL.

(2) Does the noise aggravates present damage?: Similarly to the answer under (1), the noise is not loud enough to be regarded damaging even with existing hearing loss.

(3) Does it cause stress? As @anongoodnurse suggested: yes it causes stress, apparently. Every unpleasant sensation will do so to a certain level.

(4) Effects of the noise on tinnitus: Typically, tinnitus is caused by hearing loss (see cause of tinnitus) and the pitch of tinnitus often coincides with the lost frequencies (see cause and effect of tinnitus). So if your "bad behaviors" at youth refer to loud music, then it is probably noise-induced hearing loss that has resulted in a dip at your hearing acuity at 4 kHz (the 4-kHz notch). In effect, the tinnitus you are experiencing will be around this frequency and therefore high-pitched. As the loudness of the ventilator is too low to cause damage, it is probably unrelated to your tinnitus.

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Noises over 75dB can cause temporary damage (temporary threshold shift), noises over 85dB can cause both temporary and permanent damage (permanent threshold shift). The size of the permanent damage depends on the intensity of the noise, the duration, and many other parameters e.g. genetics, antioxidants, time between two exposures, etc... For example daily 8h of 80dB is considered safe, while daily 8h of 85dB or 20mins of 100dB is considered unsafe. Tinnitus is a sign of hearing loss, so it can be both temporary and permanent.

You should measure the noise levels. For example install Sound Meter to your mobile phone. (The results can depend on the microphone. Most of the mobile phones cannot measure 100dB+ sounds, but I think this is not your case.) For example the ventilator of my computer is 35dB. I agree with Chris Stronks, that it is unlikely that your noisy ventilator caused your tinnitus or has any effects on it.

According to new studies continuous exposure to low dB (65-70) sound (which don't damage inner hair cells) can cause neural changes in sound processing. Constant noise can cause annoyance, concentration disturbance, etc... as well.

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I am a Noise Engineer and an Air-conditioning (Mechanical) Engineer, and it is my job to understand the effects of noise to our hearing capability. To start with an analogy, can you smell yourself on your pillow that you used for a long time (say 3 months)? You cannot, but a visitor who just borrowed your pillow for a night can smell it.

Now to answer the question directly, a "prolonged and constant" exposure to a low level noise, even less than 30 dBA (whisper), can cause hearing loss. Specific study showed that exposure to 40 dBA on specific frequency for 3 months will cause a hearing loss on that frequency. Notorious about this common occupational risk are those working in an improperly designed air handling system, those living/working a 2 km radius from a Wind Turbine, those living within a 1.5 km from a sub-station transformer, and many more.

What causes hearing loss is not the sound(pressure/level) itself, but the SOUND POWER. Power is a product of sound level/pressure/energy and TIME! A Firecracker is an explosion that has very high sound energy but short duration. A wind turbine sound has very low sound energy but very long duration. In effect, the product or result is the same.

I hope this has answered directly the question and put the issue to rest.

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  • $\begingroup$ Can you please provide some references to support your answer (preferably research articles)? It could be your own research too but should be published in a peer-reviewed journal. $\endgroup$ – WYSIWYG Apr 8 at 14:14

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