What feature do narrowband spectrograms primarily display?

Narrowband spectrograms primarily display harmonics of a sound signal. This type of spectrogram utilizes a long analysis window, which allows for better frequency resolution, making it particularly effective for visualizing the harmonic structure of complex sounds. In a narrowband spectrogram, each horizontal line represents a distinct frequency, which corresponds to a harmonic of the sound waveform.

Harmonics are integer multiples of the fundamental frequency and are crucial for understanding the timbre and quality of the sound. The clarity of the individual harmonics on a narrowband spectrogram provides valuable insights into the resonant characteristics of vocalizations and musical instruments, making it useful for speech analysis and other audio applications.

In contrast, while formant frequencies are important in speech and are often shown on spectrograms, their resolution is more pronounced in wideband spectrograms. Amplitude variation is typically visualized using intensity and doesn't focus specifically on frequency components, while pitch variations relate more to changes in fundamental frequency rather than the harmonic structure itself.