Turn down the volume, please.
Sound Levels
Sound levels (loudness) are measured in decibels; see https://en.wikipedia.org/wiki/Decibel
Some typical levels (approximate). For more, click HERE.
30-40 dB: Quiet room or library.
60 dB: Restaurant conversation; can be higher in crowded rooms with bare walls.
85 dB: Recommended occupational noise limits.
90 dB: Legal limit for workplace noise, established by Occupational Safety and Health Administration.
90 dB: Boeing 737 or DC-9 passenger aircraft from one nautical mile away.
110 dB: Average threshold of pain in humans.
120 dB: Chainsaw, gas powered, as heard by user. Wear ear protection !
For comparisons, 20 dB louder means 10 times as loud. 40 dB louder means 100 times as loud.
Noise reduction of 20 dB by the better noi$e-$uppre$$ing headphone$ or ear bud$ reduces outside sound levels to 1/10 as loud, not counting noise reduction by the ear muffs or seals.
Monitoring Loudness in Your Environment
Smart-phone and pad apps like Decibel X (see app store for your phone or pad) can help you to measure sound levels, and thus to know when you are in environments that are hazardous to your hearing. You should avoid, or wear hearing protection in, locations where the sound level exceeds 85 bB, which is just below the legal noise limit for workplaces. Many lawnmowers, snowblowers, leaf blowers, weed trimmers, and chainsaws exceed this limit for their users.
Online Hearing Test
In class, I will discuss briefly how to use this online hearing test. The main uses for such a test is to compare hearing in your two ears, and to monitor changes in hearing over time. This test is not a substitute for hearing tests administered by qualified medical specialists.
How do hearing aids work? In short, they pick up sounds with an external microphone, amplify it, modify it to compensate for your specific hearing loss, and then broadcast the amplified and modified sound through tiny speakers in your ear canals. Beyond that point, your ears are working in the normal way (see Science of Music, Unit 6).
How does a cochlear implant work? A cochlear implant converts the vibrations of outside sounds directly into stimulation of the hair cells in your cochlea, without relying on the hair structures of sensory cells to respond to the sound. (Almost all YouTube videos on this subject are touting a particular product. This one has a clear review of how ears normally work and how a cochlear implant works, as well as advice about questions to ask if you ever need this kind device.)
