Click the following links to learn more about sound:
Sound:
dosits.orgSound Waves:
macrosonix.comWaveforms:
techtarget.comAuditory Perception:
wisegeek.comAmplitude:
howmusicworks.orgDecibels:
earq.comSound Digitization:
cs.cf.ac.ukSampling:
clara.netQuantization:
mediacollege.comSound Compression:
music.tutsplus.comDigital Audio Compression:
ncsu.eduMP3 Compression:
techradar.comThreshold of Hearing:
hyperphysics.phyMasking
vivid-acoustics.comThis page is all about auditory perception, including what is meant by this term and the limit of human hearing. It will also explain a little more about amplitude and decibels.
What is Auditory Perception?
The physics of sound and waveforms don’t explain the full story of sound. Auditory perception refers to how human brains interpret what they hear. The perception of sound is not as simple as registering the sound wave and knowing what the sound is, it’s much more complicated than this.
In order to understand this complication, consider that humans would believe that if we heard a 200 Hz tone played softly, and then loudly, we would usually believe that the louder tone has a lower pitch than the softer one. However, if the same thing was done with a higher-frequency sound, humans wouldn’t perceive the same illusion as before.
Another interesting complication of sound is the fact that most people with good hearing would be able to hear the sound of their own name if somebody spoke it on the other side of a noisy room, even if they couldn’t perceive anything else that was said. Auditory perception is complicated indeed isn’t it?
What can Humans Hear?
Humans can hear sounds with frequencies of between approximately 20 Hz (Hertz) and 20 kHz (20,000 Hertz), though this varies for individuals. As humans age and grow into adults, we struggle to hear sounds within the upper frequency limit. Few adults can hear sounds as high as 20 kHz, but children can.
To put these frequencies in context, the highest note on a piano has a frequency of around 4186 Hz. Click the button on the left to hear this sound (ensure your volume isn’t on full blast or else you may be about to get a painful shock!
More About Amplitude &Decibels
As you have learnt, amplitude (sound pressure level) is measured in Decibels (dB). The table below shows examples of the approximate Decibels of different sounds.
Sound |
Decibels |
| Whisper | 30 |
| Typical Speech | 60 - 65 |
| Busy City Traffic | 85 |
| Motorcycle | 100 |
| Paint Begins | 125 |
| 12 Gauge Shotgun Blast | 165 |
As you can see by reading the table, we typically speak at around 60 decibels and whisper at around 30. If you think you might have problems hearing, then try this website to find out.
Always consider that anything above about 125 Decibels is the pain threshold of the human ear, and sounds that are this loud should be avoided if possible to avoid ear damage. Remember that if you’re going to a rock concert, it would be a bad idea to run onto the stage, not least because of how unhealthy it would be for your ear!