The period of a pendulum is of the pendulum. A skipper on a boat notices wave crests passing his anchor chain every 5 seconds. An insect flaps its wings to and fro at a rate of 680 vibrations per second. When you wave goodbye to someone, the flapping of your hand generates a sound wave. Lightning is seen, then ten seconds later thunder is heard.
Echoes are examples of standing waves.
The three characteristics of a musical tone are loudness, quality, and timbre. As a guitar string is tightened, the pitch of the sound produced by the string gets higher. The speed of the wave on the string when the string is tightened. Loudness is most closely associated with the of a wave. The second harmonic on a guitar string has twice the speed of the fundamental for that string.