Spectrogram

One of the types of objects in Praat. For tutorial information, see Intro 3. Spectral analysis.

A Spectrogram object represents an acoustic time-frequency representation of a sound: the power spectral density PSD (f, t), expressed in Pa2/Hz. It is sampled into a number of points centred around equally spaced times ti and frequencies fj.

Inside a Spectrogram

With Inspect, you will see the following attributes:

xmin
start time, in seconds.
xmax
end time, in seconds.
nx
the number of times (≥ 1).
dx
time step, in seconds.
x1
the time associated with the first column, in seconds. This will usually be in the range [xmin, xmax]. The time associated with the last column (i.e., x1 + (nx – 1) dx)) will also usually be in that range.
ymin
lowest frequency, in Hertz. Normally 0.
ymax
highest frequency, in Hertz.
ny
the number of frequencies (≥ 1).
dy
frequency step, in Hertz.
y1
the frequency associated with the first row, in Hertz. Usually dy / 2. The frequency associated with the last row (i.e., y1 + (ny – 1) dy)) will often be ymax - dy / 2.
zij, i = 1 ... ny, j = 1 ... nx
the power spectral density, in Pa2/Hz.

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© ppgb, March 21, 2007