Scream pipe

Can you scream as loudly as an animal? The barrel has a microphone connected to an amplifier. The intensity of the sound produced is measured in decibels and displayed as a column of lamps.

Sound is generated by changing air pressure. The earth has a constant air pressure called atmospheric pressure. When a person speaks, the vocal cords oscillate (move backwards and forwards) which changes the air pressure making it either higher or lower than atmospheric pressure. The pressure difference is called amplitude and affects volume which is measured in decibels (dB). So a lion’s roar has a high amplitude.

The sound’s frequency is how often the vocal chords oscillate. Sound frequency is measured in Hertz (Hz). It measures how many pressure waves hit the eardrum every second. If the vocal cords oscillate many times per second, there are more sound waves, which means the peak distance between the waves is short. The distance between the peaks is called wavelength and affects frequency. Shorter wavelengths create squeakier sounds, whereas lower wavelengths produce muffled sounds.