Sound waves
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32 terms
Terms | Definitions |
|---|---|
 Sound | Longitudinal, mechanical wave produced by the vibration of a material object |
| Range of human hearing | Sound waves that are between 20-20,000 Hz (audible) |
| Infrasonic | Sound waves less than 20 Hz which is too low to be heard |
| Ultrasonic | Sound waves that are greater than 20,000 Hz which is too high to be heard |
| Doppler effect/shift | A change in frequency due to relative motion between the source of waves and an observer. If the source and the observer are getting closer, the observed frequency would be higher |
| Bow wave | V shaped, two dimentional, overlapping crests |
| Shock wave | Cone shaped, three dimentional. Object is moving faster than the waves it is creating |
| Sonic boom | Loud sound heard when the conical shell of compressed air from a shock wave strikes your eardrum |
| Supersonic | Faster than the speed of sound |
| Subsonic | Slower than the speed of sound |
| Mach number | Number of times the speed of sound |
| Pitch | Percieved highness or lowness of a sound, depending on the frequency of the sound waves |
| Echo | A reflection of sound arriving at the listener some time after the direct sound |
| Reverberation | Multiple echos |
| SONAR | (Sound Navigation and Ranging) Generic name for the technology that is used to locate objects underwater on a basis of acoustic echo. |
| Echolocation | SONAR used by animals. |
| Dead spots | Sound waves intefering destructively which cause spots of low amplitude. |
| Loudness or volume | Percieved size of sound wave. |
| Intensity | Rate at which sound energy is transfered through a unit area. |
| Decibel | Scale for measuring relative intensity. Loudness is a factor of 2. Intensity is a factor of 10. |
| Threshold of hearing | The softest sound that can be heard by the average human ear. (0 db) |
| Threshold of pain | Level above which audible sounds are painful. (120 db) |
| Elasticity | The ability of a material to resume its initial shape, the more elastic the medium, the better sound travels through it. |
| Consonance | Pleasant sound when 2 or more pitches in small whole number ratios are played at the same time. (chords) |
| Dissonance | Unpleasant sound when 2 or more pitches played at the same time are not in small whole number ratios. |
| Octave | 2 notes with frequencies related by the ratio 1:2 |
| Beats | The inteference of 2 slightly different frequencies of sound cousing a fluctuation in loudness |
| Beat frequency | The number of beats per second. fb=If2-f1I |
| Natural frequency | Special sound formed from an objects own unique set of frequencies |
| Forced vibrations | Sound produced when an object is forced to vibrate at a certain frequency by another object. |
| Resonance | A dramatic increase in amplitude when forced vibration matches objects natural frequency |
| Timbre (pronounced tambray) | tone color/quality due to presence of harmonics.(distinguishing different instruments playing the same note) |
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