Sound

• Sound waves are produced by vibrating bodies
• Vibrations of bodies cause the air around them to vibrate, producing the sensation of sound in our ears
• Examples of sound production include vibrations of guitar strings, vocal chords, human heart beats, and other organs like lungs
• Doctors use stethoscopes to hear sounds produced by the human body
• A tuning fork is used in school laboratories to produce sound waves when struck against a rubber hammer
• Loudness is a characteristic of sound that distinguishes between loud and faint sounds
• Factors affecting loudness include the amplitude of the vibrating body, the area of the vibrating body, and the distance from the vibrating body
• Pitch is a characteristic of sound that distinguishes between shrill and grave sounds
• Pitch depends on the frequency of the sound
• Quality is a characteristic of sound that distinguishes between sounds of the same loudness and pitch
• Intensity of sound is the amount of sound energy passing per second through a unit area held perpendicular to the direction of sound wave propagation
• Intensity level of sound is measured in decibels (dB) on a scale known as the decibel scale
• Decibels (dB) is a logarithmic measure of the amplitude of sound waves
• Equal intervals in a logarithmic scale correspond to multiplying by 10 instead of adding equal amounts
• Reflection of sound is caused by the bouncing back of sound waves from a surface, resulting in an echo
• To hear a clear echo, the time interval between the original sound and the reflected sound must be at least 0.1 s
• The speed of sound in air is 343 m/s at one atmosphere of pressure and room temperature (21°C)
• The audible frequency range for a normal human ear is between 20Hz and 20,000 Hz
• Ultrasound, or ultrasonics, are sounds of frequency higher than 20,000 Hz that are inaudible to the normal human ear
• Ultrasound waves carry more energy and higher frequency than audible sound waves
• Ultrasound is used in medical fields for diagnosis and treatment, such as detecting blood clots and locating objects underwater
• Bats can hear frequencies up to 120,000 Hz, while humans can hear up to about 20,000 Hz
• Sound is produced by a vibrating body and travels in the medium in the form of compressional waves
• Loudness of sound depends on the amplitude, surface area, and distance from the vibrating body
• Intensity of sound is the sound energy flowing per second through unit area held perpendicular to the direction of sound waves
• Pitch of sound depends on the frequency and distinguishes between shrill and grave sounds
• Quality of sound distinguishes between two sound waves of the same loudness and pitch
• Musical sounds have a pleasant effect on our ears, while noise has a jarring effect
• Noise pollution is a major concern in big cities and can be reduced by using environment-friendly machinery and equipment, sound-reducing barriers, or hearing protection devices
• Acoustic protection is the technique used to absorb undesirable sound energy by using soft and porous surfaces
• Sound waves are produced by vibrating bodies
• Vibrations of bodies cause the air around them to vibrate, producing the sensation of sound in our ears
• Examples of sound production include vibrations of guitar strings, vocal chords, human heartbeats, and other organs like lungs
• Doctors use stethoscopes to hear sounds produced by the heart and other organs
• Sound is produced by a vibrating body
• In school laboratories, a tuning fork is used to produce sound waves by striking it against a rubber hammer
• We can hear the sound produced by a tuning fork by bringing it near our ear
• We can feel the vibrations of a tuning fork by touching one of the prongs with a plastic ball suspended from a thread
• Sound requires a material medium for its propagation
• Unlike light waves, sound waves require a material medium for their propagation