SOUND

SOUND

1. PROPERTIES OF SOUND WAVE

   • amplitude determines loudness
     • Amplitude refers to the distance of the maximum vertical displacement of the wave from its mean position. Larger the amplitude, the higher the energy. In sound, amplitude refers to the magnitude of compression and expansion experienced by the medium the sound wave is travelling through. This amplitude is perceived by our ears as loudness. High amplitude is equivalent to loud sounds.
   • frequency determines pitch
     • Frequency in a sound wave refers to the rate of the vibration of the sound travelling through the air. This parameter decides whether a sound is perceived as high pitched or low pitched. In sound, the frequency is also known as Pitch. The frequency of the vibrating source of sound is calculated in cycles per second.

2. FREQUENCY

   • The frequency of a wave refers to how often the particles of the medium vibrate when a wave passes through the medium. The frequency of a wave is measured as the number of complete back-and-forth vibrations of a particle of the medium per unit of time. If a particle of air undergoes 1000 longitudinal vibrations in 2 seconds, then the frequency of the wave would be 500 vibrations per second. A commonly used unit for frequency is the Hertz (abbreviated Hz), where 1 Hertz = 1 vibration/second

3. LOUDNESS

   • Loudness is the property by which one can distinguish between two sounds of the same frequency and pitch. The loudness of sound is determined by the intensity and amplitude of the sound waves. The loudness of sound is directly proportional to the square of the amplitude of vibration and If the amplitude of the sound wave is large, then the sound is said to be loud.

4. INTENSITY

   • The amount of energy that is transported past a given area of the medium per unit of time is known as the intensity of the sound wave. The greater the amplitude of vibrations of the particles of the medium, the greater the rate at which energy is transported through it, and the more intense that the sound wave is. It is measured in decibels (dB)

5. PITCH AND RESONANCE

   • a condition that exist when the frequency of a force applied to a system matches the natural frequency of vibration of the system

6. USES OF SOUND IN EVERYDAY LIFE

   • Small speakers in your headphones use electricity and moving magnets to create sound waves. The sound waves that come from the speaker bounce off your eardrums, which your brain interprets as music. Sound waves that you hear, whether they come from another person or a speaker, bounce off objects and move through the air and into your ears. Your brain uses the waves to interpret where a sound is coming from and how loud it is.
   • Speaking (as well as hearing) involves vibrations. To speak, we move air past our vocal cords, which makes them vibrate. We change the sounds we make by stretching those vocal cords. When the vocal cords are stretched we make high sounds and when they are loose we make lower sounds. This is known as the pitch of the sound.
   • Ultrasound is sound with a frequency higher than 20 kHz. This is above the human range of hearing. The most common use of ultrasound, creating images, has industrial and medical applications. The use of ultrasound to create images is based on the reflection and transmission of a wave at a boundary. When an ultrasound wave travels inside an object that is made up of different materials (such as the human body), each time it encounters a boundary (e.g., between bone and muscle, or muscle and fat), part of the wave is reflected and part of it is transmitted. The reflected rays are detected and used to construct an image of the object.
   • A sound wave is transmitted and bounces off the seabed. Because the speed of sound is known and the time lapse between sending and receiving the sound can be measured, the distance from the ship to the bottom of the ocean can be determined. This technique is called sonar (originally an acronym for SOund Navigation And Ranging).