Matlab audio recording signals frequency sampling I am a lit

Matlab audio recording, signals, frequency, sampling

I am a little confused on this plot of an audio recording I recorded using Matlab. The prompt said to read \"Hello, DSP is fun.\" Once recorded the plot came out like so:

Here is some additional info:

SampleRate: 8000

       BitsPerSample: 16

    NumberOfChannels: 2

            DeviceID: -1

       CurrentSample: 257

        TotalSamples: 40000

             Running: \'on\'

            StartFcn: []

             StopFcn: []

            TimerFcn: []

         TimerPeriod: 0.0500

                 Tag: \'\'

            UserData: []

                Type: \'audioplayer\'

So a few questions: Is the x-axis the samples? I am assuming so since the total samples is 40000. I know its not time. And what is the y-axis? frequency in Hz? If I wanted to convert the x-axis to time how would I do so? The sampling frequecy is 8000 Hz. The sampling interval is 1/Fs and T=n*Ts. So do I just multiply the sampling interval by 40000?

Help would be very appreciated! Thanks

0.8 0.6 0.4 0.2 -0.2 -0.4 -0.6 -0.8 0.5 1.5 25 3.5 10

Solution

From the above given graph, what the X-axis represents is \"Time\" only, so no need to convert it .

and the Y-axis represents amplitude of the audio signal.

sampling rate is simply calulated as  1/Fs only.so u can do multiplication