The term frequency for a periodic wave can be defined as the number of times a repeating pattern occurs in a given time period (eg: no. of crest and trough cycles per second for EM wave). But what does frequency mean in the context of a human voice? I was trying to understand Modulation (out of interest) and human voice is plotted with time of $x$-axis and amplitude on $y$-axis. And amplitude/frequency of carrier is modulated based on amplitude of the input signal. Where is frequency dimension? Can someone please help me here?
Really sorry about typo in the previous version of the question. I meant to understand the frequency dimension in a typical human voice and not really interested about exact values. More specifically, if frequency of voice is plotted against time, how does the graph look? And, in general graphical representation of voice, what is plotted against time, frequency of amplitude?
Best Answer
Human voices tend to average around middle C - male voices average an octave below this and female voices an octave above. Middle C is 261.6Hz.
If you have an amplitude-time graph the way to measure the frequencies contained in it is to Fourier transform it. This gives you a plot of amplitude against frequency. If you take some reasonable clear signal, like a singer singing a constant note, you should see a clear fundamental frequency and overtones. For some random bit of speech you'll most likely get a broad range of frequencies.