What is Pitch and Frequency?
An important measure of sound is frequency. It is the speed at which the sound wave vibrates. This is different from the speed at which the wave travels through the medium. Frequency is measured in hertz. The faster the sound wave vibrates, the higher it is.
For example, on a guitar, a large, heavy string will vibrate slowly and produce bass or high pitch. Thinner, lighter strings vibrate faster and produce a higher pitch or sound.
Talking
Not only is it important to hear sounds, but we also create sounds to communicate. The process of producing the correct sound for speech is complex and involves many parts of the body working together. Sound is produced by the vocal cords vibrating in our throat.
This way we can adjust our volume and pitch. We also use our lungs to force air through our vocal cords and make them vibrate. We also use our mouths and tongues to help form specific sounds. It’s amazing how much sound can be produced, let alone the complex sound systems humans can create for verbal communication.
Acoustics
Acoustics is the study of how sound travels. It is important to control the behavior of sound and its use in the design of buildings such as auditoriums, theaters and libraries. In some cases, acoustics are used to help the sound travel.
For example, in a large concert hall, acoustics help ensure that everyone in the building, including those in the back seats, can hear the music. In a library, soundproofing helps prevent sound from traveling to help keep the library quiet. There are two main ways to control
There are two main ways to control acoustics:
Reverberation – Reverberation is how sound bounces off things. Typically, a “noisy” room will be one with sound bouncing off walls and floors. Some materials resonate better than others. For example, a tiled floor will reflect sound better than a carpeted floor (which will absorb sound).
Absorption – Unlike reverberation, sound-absorbing elements do not reflect vibrations. Soft items like rugs and curtains will help absorb sound and make the room quieter.
The Doppler Effect
If you are standing still and a car passes in front of you, the frequency of the sound changes as the car passes you. This is called the Doppler effect. The pitch of the sound will be higher when the car is coming towards you, then lower when the car is moving away. The sound produced by the vehicle does not change. Its frequency is the same.
However, when a car is moving towards you, the speed of the car causes the sound waves to hit your ears faster or at a higher frequency than the car generating them. When a car passes you, the sound waves reach your ears at a lower frequency. The Doppler effect is named after scientist Christian Doppler, who discovered it in 1842.