The maximum number of beats per second that a human ear can distinguish is

What is beat frequency?

$56$ tuning forks are arranged such that each fork produces $4$ beats per second with its previous one. If the frequency of the last fork is twice that of the first, the frequency of the $19^{\text{th}}$ fork is . . . . . . (in $\text{Hz}$)

$A$ tuning fork of known frequency $256\,Hz$ produces $5$ beats per second with the vibrating string of a piano. The beat frequency decreases to $2$ beats per second when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was

Ten tuning forks are arranged in increasing order of frequency in such a way that any two consecutive tuning forks produce $4$ beats per second. The highest frequency is twice that of the lowest. Possible highest and lowest frequencies (in $Hz$) are ................

Two sources of sound are emitting progressive waves $y_1 = 4 \sin 708 \pi t$ and $y_2 = 3 \sin 700 \pi t$. The sources are placed close to each other. The number of beats heard per second and intensity ratio between waxing and wanning are respectively