| Decibel (dB) | The unit of measure loudness level of sound. It’s a logarithmic scale where a small change in decibel level represents a large change in sound intensity. For example, a whisper might measure around 20 dB, while a rock concert can exceed 120 dB. |
| Amplitude | The measure of intensity of a sound wave determines its volume or loudness. Greater amplitude means a louder sound. |
| Echo | The reflection of sound waves off a surface, results in a repetition of the sound after a delay. It occurs when sound waves bounce off a surface and return to the listener. |
| Frequency | The number of cycles of a sound wave that occur per second is measured in Hertz (Hz). Higher frequency corresponds to higher pitch, while lower frequency relates to lower pitch. |
| Hertz | SI unit of frequency, 1 hertz (1Hz) = 1 vibration per second. |
| Larynx | Sound producing organ (voice box) in humans. |
| Loudness | The degree of sensation of sound depends on the frequency of sound. |
| Pitch | Characterized of sound depending on the frequency of sound. |
| SONAR | A technique used to determine the depth of the sea and locate underwater objects. |
| Timber | The characteristics of sound that help us to distinguish between two sounds of the same loudness. |
| Vacuum | Absence of all material particles |
| Vibration | High-frequency oscillations. |
| Harmony | The combination of different musical notes played or sung simultaneously to create a pleasing sound. Harmony adds depth and richness to music. |