Which one of the following statements is not correct ?

The statement that the loudness of sound is related to its frequency is incorrect. Loudness is primarily determined by the amplitude of the sound wave, whereas frequency determines the pitch. An increase in decibels, which measures sound level, corresponds to an increase in perceived loudness. Pitch is the characteristic that allows us to distinguish between male and female voices, as males typically have lower fundamental frequencies (90-155 Hz) compared to females (165-255 Hz) [2]. Musical sounds consist of a fundamental frequency and its harmonics, which are integer multiples of that base frequency [3]. Timbre, the quality that distinguishes different instruments or voices at the same pitch and loudness, is determined by the specific waveform and the relative amplitudes of its constituent harmonics [3].

Sources

1. [2] https://en.wikipedia.org/wiki/Voice_frequency
2. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC3826062/