am i hearing things?

My dad just bought headphones as a gift for my grandmother and I didn't really think about them. However, I heard this irritating high pitched squeal one morning, but when I asked my parents if they heard the noise they said they couldn't hear anything. When I found out the noise was coming from the headphones I told my dad and he thought I was messing with him because he couldn't hear anything. Apparently the frequency of the noise is too high for either of my parents to hear anymore. Like we learned in class, humans can have a hearing range from 20 Hz to 2000 Hz, but it varies from person to person. Once a frequency is outside of a person's range, they no longer hear it. However, since I can hear it, my grandmother's dog probably can, too.

wave action

Ocean waves have the same characteristics as the waves we are learning about right now. The velocity of a wave stays constant, even when frequency or wavelength changes. Ocean waves are both transverse and longitudinal waves because particles on the wave move both perpendicularly and parallel to the direction of the wave. They also pass through one another. Ocean waves are example of waves that are easier to understand than sound waves, because they can actually be seen and observed. An example of wave observation would be when people pick opihi. They count the big waves, which normally come in threes, and then go down to pick during the lull that comes right after the last wave. The pickers still have to watch the waves, but the frequency and pattern of the waves stays relatively constant. I'm not really sure why they come in threes though.

Sound waves

During spring break, a bunch of us went to waikiki for karaoke and although I didn't know much about the subject at the time, there were a lot of sound waves. Higher voices have a higher frequency. However, because frequency is equal to the reciprocal of the period of the wave, higher voices have smaller periods. Even when frequency changes, it does not affect the speed of the sound wave. This is because speed=frequency x wave length and frequency and wave length have an inverse relationship. This is why two people can be singing a duet at different frequencies, but their voices will be heard by others at the same time. So there really is physics even in singing.