Sound and Music

Sound Characteristics of Sound

Important: There is no sound in vacuum Important: There is no sound in vacuum! For sound waves to travel you need an elastic medium!

Speed of Sound in the Air: v=(331 + 0.6T) m/s, Where T is the temperature in C.

Conceptual Example: Distance from Lightning Strike A rule of thumb that tells how close lightning has hit is:”one mile for every five seconds before the thunder is heard:. Justify, noting that the speed of light is so high that the time for light to travel is negligible compared to the time for sound.

Loudness is related to the energy in the sound wave. The pitch of a sound refers to whether it is high, like a sound of piccolo or low like string bass. The lower the frequency of sound, the lower the pitch.

Audible Frequency Range The human ear responds to frequencies in the range from about 20Hz to 20000 Hz. It could slightly depend on individuals.

“Pressure Waves”

Sources of Sound: Vibrating Strings and Air Columns

The lowest three frequencies in the string

Interference and Sound Waves

Beats

Doppler Effect

Shock Waves and Sonic Boom

Which of the following properties of a sound wave determines its loudness (or intensity): wavelength, speed, amplitude, or frequency? Which of these properties determines its pitch? How does the fundamental frequency of an organ pipe, which is open at both ends, change as you close one of the ends? How does the wavelength of the fundamental standing wave on a violin string compare with the length of the string?

You have an organ pipe that resonates at frequencies of 300, 450, and 600 hertz but nothing is between. It may resonant at lower and higher frequencies as well. Is the pipe open at both ends or open at one end and closed at the other? How can you tell? Same for 500, 700 and 900 Hz. An automobile sounding its horn is moving toward you at a constant speed. How does the frequency you hear compare with that heard by the driver?