If the frequencies of two component waves are 24 Hz an 20 Hz, they should produce beats per second

When two waves combine, they produce two new waves.

The frequencies of the two new waves are

(the sum of the two original frequencies)

and

(the difference of the two original frequencies).

The new waves are called the 'beats'.

If the frequencies of the two original waves are 24 Hz and 20 Hz,

then the frequencies of the beats are

(24 + 20) = 44 Hz

and

(24 - 20) = 4 Hz.

These are called the 'beat frequencies'.