WHAT DO WE KNOW ABOUT SOUND? Sound is a form of energy; the explosion of the volcano Krakatoa was heard 6,000 miles away. Other sounds have almost no energy - like the pebble that drops in the river. However, ALL sounds behave in the same way.
Sound begins at a SOUND SOURCE. –W–What do you hear? YES, a typewriter
SOUND SOURCE So, the sound source is where the sound is coming from. Click to hear a sound source.
SOUND RECEIVER Inside your ear a complex sequence of mechanical and neurological processes receive and interpret the sounds. Your ear is a Sound Receiver. Sound can be heard from above, below, or any direction because sound travels in every direction from a source.
VIBRATION Look at a triangle. If you look closely you will see that it vibrates when making a sound. When the triangle was whacked with the stick, energy was transferred to the metal and it started to vibrate. When the energy is used up, it stops vibrating. The sound stops. Sound will continue only as long as there is energy in the system to keep it going.
HOW SOUND TRAVELS Sound travels from one place to another through thin air. Sound can also travel through other gases, liquids, and even through solids. The only thing sound can not travel through is a vacuum.
VOLUME and PITCH Sounds can be loud or soft. They can sound high or low. Volume (loud/soft) is a measure of the amount of energy in the sound – the more energy, the louder the sound. Sound is measured in decibels. A whisper is about 10 decibels. A jackhammer is 100 decibels. Sounds over 90 decibels can cause hearing loss.
Pitch is a product of rate (or frequency) of vibrations. The faster the vibrations, the higher the pitch of the sound. The slower the vibrations, the lower the sound.