Spectrographic Analysis of Speech

  • Wideband spectrogram provides higher temporal resolution at the cost of spectral resolution.

  • Narrowband spectrogram provides higher spectral resolution at the cost of spectral resolution.

  • Wideband spectrogram uses a short window size (typically 5 ms) for analysis, which results in a broader main lobe of the spectrum of the window signal. This smears or smoothens the spectral features of the speech segment thereby reducing the spectral resolution.

  • Periodicity information of voiced sounds is reflected as vertical striations in WB spectrogram, while the pitch harmonics manifest as horizontal striations in NB spectrogram.

  • Spectrogram reading (i.e., to decipher the message from the spectrogram alone) is possible, but requires a lot of training.

  • There are transitions among sound units, which can be used for marking boundaries between the units.