Topping SHA's Noisy Toys List this year is Fisher Price's Shake 'N Go Mater, a toy car that literally screeches at 120.8 dB. At that level, a person starts to risk hearing damage in less than eight seconds, according to National Institute of Occupational Safety and Health (NIOSH) guidelines. Interestingly, "Mater's" friends, Ramone and The King, were some of the loudest toys on last year's list.

The second loudest toy on the list is the Little People ABC Letter Sounds puzzle. This toy, meant for a 1 ½ -year-old toddler, sounded off at 114.5 dB. At 113.5 dB is the Disney High School Musical Rockerz Boomin' Drums, a handheld musical toy made by Zizzle. Mattel's Speed Racer Mighty Mach 5 Racing Wheel made it into the top four loudest at 112.8 dB. Other notables on the list are the Press & Go Animal Parade, a toy recommended for babies six months and up, which rang out at 109.3 dB.

Resident otolaryngologists at the University of Minnesota tested the toys for the Sight & Hearing Association in a sound-proof chamber.

There is one toy SHA found to add to its Ear-Friendly Toys list, a list of toys with sounds the organization highlights for their low levels. The VTech Bright Lights Phone measured 80.3 dB directly at the speaker, a safe level for more than eight hours.

Sounds that are 85 dB or louder can permanently damage hearing. The louder the sound, the less time it takes to cause damage. For example a sound at 85 dB may take as long as eight hours to cause permanent damage, while a sound at 100 dB can start damaging hair cells after only 15 minutes of listening. According to NIOSH, part of the Centers for Disease Control, the permissible exposure time (the amount of time you should listen) is cut in half with every three decibels over 85 dB.

Click here to view 2008 Noisy Toys List. (pdf)

Because of a child's shorter arm span, toys are often potentially more dangerous to hearing because children hold them closer to their ears. Some toys, like play cell phones, are meant to be held close-to-the-ear. This year, SHA tested another play cell phone, the VTech Dial & Discover Phone. Made for a six-month-old, this toy measured at 98.5 dB. In the Sight & Hearing Association study, the toys were repeatedly tested at distances simulating how a child might hold the toy, directly near the ear (0 inches) and at arms' length (10 inches). A soundproof acoustic chamber was used to ensure accurate measurements.

Until five years ago, there were no regulations in the United States regarding the loudness of toys. An acoustics standard (ASTM F963), adopted and revised in March 2004 by ASTM International, states that a hand-held, table-top or crib toy cannot exceed 90 dB 25 cm (approx. 10 in.) from the surface of the toy. Compliance with the standard is voluntary. Directly at the speaker of the toy, all of the toys tested this year measured louder than 90 dB. At 10 inches from the toy's surface, three of the toys measured louder than 90 dB: the Speed Racer Mighty Mach 5 Racing Wheel (93.9 dB), the Nano Blaster (92.2) and Shake 'N Go Nascar Jimmie Johnson (92.8).

So what should you do if your child receives a noisy toy this Christmas?

• Place clear packing tape over the speaker of the toy. This helps muffle the sound level.
• If the toy has a volume button, make sure it's turned to the lowest setting. Repeatedly check the toy. (Kids like to move buttons!)
• Report the noisy toy to the Sight & Hearing Association at ReportAToy@sightandhearing.org or call the Consumer Product Safety Commission at 1-800-638-2772.

How NIHL happens
There are roughly 40 million Americans suffering from hearing loss, of which 10 million can be attributed to noise-induced hearing loss (NIHL). NIHL can be caused by a one-time exposure to loud sound as well as by repeated exposure to sounds at various loudness levels over an extended period of time. Damage happens to the microscopic hair cells found inside the cochlea. These cells respond to mechanical sound vibrations by sending an electrical signal to the auditory nerve. Different groups of hair cells are responsible for different frequencies (rate of vibrations). The healthy human ear can hear frequencies ranging from 20Hz to 20,000 Hz. Over time, the hair cells may get damaged or broken. If enough of them are damaged, hearing loss results. The high frequency area of the cochlea is often damaged by loud sound.

Decibels : Permissible exposure time
140 dB = Immediate danger
118 dB ~ 15 sec.
115 dB ~ 30 sec.
112 dB ~ 1 min.
109 dB < 2 min.
106 dB < 4 min.
103 dB= 7.5 min.
100 dB= 15 min.
97 dB = 30 min.
94 dB =1 hour
91 dB = 2 hours
88 dB = 4 hours
85 dB = 8 hours
60-70 dB = Normal conversation
30 dB = Whisper