Pitch, Loudness, and Quality of Sound

1. Pitch, Loudness, and Quality of Sound by RifkiIrawan

4. Frequency and Pitch Pitch = frequency of sound The perceived pitch of a sound is just the ear's response to frequency. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. A high pitch(>2kHz) will be perceived to be getting higher if its loudness is increased, whereas a low pitch (<2kHz) will be perceived to be going lower with increased loudness. The ear has an ability to detect such frequencies and associate them with the pitch of the sound, because sound waves traveling through air are longitudinal waves which produce high- and low-pressure disturbances of the particles of the air at a given frequency.

5. Low frequency wave pressure time period The pitch of a note increases with the frequency of vibrations High frequency wave pressure time period

6. Intensity and Loudness The intensity of a sound wave depends on the amount of energy in each wave. Intensity of a sound wave increases as its amplitude increases. Loudness is the human perception of sound intensity. The higher the intensity and amplitude, the louder the sound . The loudness of a sound increases with the amplitude of vibration . The intensity of a sound is measured in units called decibels (dB) . The faintest sound that can be heard by most human ear is 0 dB. Sound with intensities above 120 dB may cause pain and hearing loss .

7. Familiar sounds and their intensity

8. Note that the prolonged listening to loud music through headphones/earphones can damage your ears as well Noise Level (dB) Effect Pin dropping 0 Limit of hearing Soft whisper 30 Soothing Hair dryer 50 Normal conversation possible School dining hall 60 Disturbing Motorcycles and cars 80 Annoying if not involve The noise levels of common sounds Pneumatic drill 90 Signs of ear damage; ringing in ears Shouting in ear 100 Working efficiency falls Heavy hammering machine 110 Conversation impossible Police car sirine 120 Ear uncomfortable Music concert 130 Ear pain Nearby jet at take off 140 Unbearable > 150 Ear damage

9. Intensity Calculation The amount of energy which is transported througha given area of the medium per unit of time is known as the intensity of the sound wave. Energy Power = Intensity = Time x Area Area Typical units for expressing the intensity of a sound wave are Watts x meter-2 ( W ∙ m -2).

10. String instruments : • The pitch of the notes produced by stringed instruments depends on : • the tension • the length; and • the mass per unit length (or thickness) • To obtain a note of higher pitch, the frequency of the string can be increased in the following ways : • increasing the tension • shortening the length; and • using the thinner string of smaller mass per unit length

11. Humans are equipped with very sensitive ears capable of detecting sound waves of extremely low intensity = 0 dB 0 dB = 1 x 1012W ∙ m-2 0 dB = a sound which will displace particles of air by one-billionth of a centimeter have a nice day ! This faintest sound which a human ear can detect is known as the threshold of hearing ( TOH ) To be continued . . . ! thank you for watching