Final answer:
An ascending pitch occurs when the frequency of a sound wave increases, which is perceived by our ears as a higher pitch.
Step-by-step explanation:
The term used to indicate when pitches are going up is ascending pitch. This can happen when the muscles of the larynx adjust to tighten the vocal cords, which increases the frequency of the vibration and results in a higher pitch. The frequency of a sound wave is indeed what our ears perceive as pitch; a higher frequency equates to a higher pitch, like the chirp of a bird, while a lower frequency results in a lower pitch, such as the roar of a lion.