Question

what does frequency, measured in hertz (hz), indicate about sound?
the duration of the sound
the loudness of the sound
the temperature of the sound
the number of sound vibrations in a single second

Explanation:

Frequency is defined as the number of vibrations or cycles per second. Hertz (Hz) is the unit of frequency. The direction of sound is not related to frequency. Loudness of sound is related to amplitude. Temperature is a separate physical quantity. So, frequency (in Hz) indicates the number of sound vibrations in a single second.

Answer:

The number of sound vibrations in a single second