zero crossing in sound signal

is there a bulit in function for zero crossing in sound signal and if there isn't can you teach me one

Answer 1

[Gita]

Write your code using diff and sign functions

[Walter Roberson]

That algorithm does not appear to account for noise or measurement error

[Gita]

Filtering might be helpful

[Walter Roberson]

Consider the case of successive approximations to a square wave by adding more frequencies. The "top" of the square wave starts sinusoidal with low frequencies, and the relative period and amplitude of the sinusoids gets lower and lower, with the top more and more closely approximating a straight line to the level of our visual acuity. But at any stage before the infinite, examine with sufficient resolution and you will still see many increases and decreases on a local level along the top. None of those increases or decreases has anything to do with zero crossing of the signal.

Thus, purely local algorithms (including local smoothers) cannot be used to detect zero crossings with any reliability.