In our apartment complex we have fire alarms that are outrageously loud. Last night, we woke at 4:30 am to the alarm going off all through the building. We got out as quickly as possible, but I'm worried about my 4 month old. The alarm is loud enough to make my ears ring and even pretty far away from the building it was louder than I liked. The alarm rang for about half an hour and this is the second time it has happened since my son was born. How much noise does it take to damage hearing and can early hearing loss be recovered if you are not exposed to more noise?
Infants are especially susceptible to hearing damage from loud noises because their skulls are thinner, according to the Women’s and Children’s Health Network.
We are born with tiny sensors in the inner ear called “hair cells”. Throughout life, we lose hair cells very slowly resulting in frequent gradual loss of hearing with age. Loud noise can lead to the sudden death of many hair cells while exposure to prolonged noise results in continual and accelerated loss of cells. The cumulative effect of that loss results in earlier hearing difficulties for children who are exposed to damaging noise at a young age.
Therefore, safe levels can vary according to the duration of the exposure and the loudness level. Noises less than 75 to 80 decibels (the equivalent to noise in a restaurant or in city street traffic) should not cause hearing damage, according to The Children’s Hearing Institute. A normal conversation is about 60 decibels.
My research revealed that the suggested sound level for fire alarms is 5 to 15 dB above the normal sound level existing at the site with maximum at 110 to 120 db depending on the standard specs in different locals.
If the sound level of your alarms are above 80 dB (which is very likely) there is significant risk for you and your child's hearing. If their loudness in is the 110-120 dB range the risk is even greater.
I’d recommend that you get ear protection for yourself and for your child that will be readily available to use when needed.
Per http://www.e-a-r.com/pdf/hearingcons/NIHLChildren.pdf there are no product specifications for hearing protection devices for children under age 5 years. The malleable (wax) ear plugs lose some of their protective quality in young children because the full amount will not usually fit in their ears. These plugs also present a swallowing and choking hazard. Other devices include corded plugs pinned to a child's clothing and ear muffs.
In the end of the reference above, there are photos of devices available for children. I was impressed with the Natus MiniMuffs adhesive earmuffs recommended for NICUs during use of ventilators, MRIs or emergency transport.
The device you select should fit well and be comfortable with good sound blockage. The U.S. Environmental Protection Agency requires all products be labeled with a Noise Reduction Rating (NRR). The numbers are based on optimum fitting in idealistic conditions therefore it is recommended that the NRR be used as a guide that the device was designed and tested for noise reduction.
I applaud your awareness of the impact of noise on your child's hearing! As a speech-language pathologist, I work with children and adults who suffer from the consequences of prolonged exposure to noise. Thank you for presenting such a timely and beneficial question to SE Parenting.
Sound volume is measured in decibels (dB). Hearing damage starts at 120 dB, although prolonged exposure to just 85 dB can also cause damage. Here is a chart that lists some relative values with examples. Damage can be temporary (e.g. disco), but if the noise was loud enough (e.g. explosion) then the damage can also be permanent. Talk to a pediatrician or your own doctor if you're concerned about measuring and treating any damage that has potentially already been done. Read more about noise-induced hearing loss here.
However, it takes a lot less volume to make your ears ring (especially at the high frequencies used by fire alarms), so luckily your ringing ears are not an automatic indication of hearing damage.
Fire alarms are of course meant to be very loud, so that not even the deepest sleeper would overhear it. But I do not believe that they would be that loud as to cause actual hearing damage. Although it's a fact that children's ears are more sensitive than adults' ears, I don't think that a child's ear is more easily damaged.
To prepare for future fire alarms, buy some disposable earplugs at your local pharmacy. The best ones are made from soft wax (the size of a small marble) that you heat with your fingers and push onto the ear; talk to the pharmacist for guidance concerning infants. You can also get regular headset-style ear protectors (used in e.g. factories). These are nearly as effective and more convenient to use, but more bulky to store.
Also, when the fire alarm goes off, move as far away as you can and/or go sit in the car with all the windows closed.