Using the Spectrogram and Waveform Display

 

About the Spectrogram Display

The spectrogram shows a range of frequencies (lowest at the bottom of the display, highest at the top) and shows how loud events are at different frequencies. In general loud events will appear bright and quiet events will appear dark. The spectrogram can let you see at a glance where there is broadband, electrical and intermittent noise, and allows you to isolate audio problems easily by sight. RX features an advanced spectrogram display that is capable of showing greater time and frequency resolution than other spectrograms, allowing you to see an unprecedented level of detail when working with audio.

 

Transparency

The Spectrogram Display features a transparency slider which lets you superimpose a waveform display over the spectrogram, allowing you to see both frequency and overall amplitude at the same time. This can be invaluable for quickly identifying clipping, clicks and pops, and other events.  

 

Configuring resolution

The Spectrogram Display can be configured to show a high level of detail for critical applications. For example, this is vocal recording represented with standard spectrogram settings and then with a high quality "reassigned" mode:

Regular spectrogram settings

 


Spectrogram in "Reassigned" mode

 

In situations where you would like to see crisper detail, go to the View|Spectrogram Settings menu. There are presets in this menu for some of the more useful settings.

 

Changing Spectrogram Colors

RX's Spectrogram Display also allows you to choose from different color schemes. To choose from different color presets go to View|Spectrogram Settings.

 

Amplitude Scale

You can right-click on the spectral amplitude ruler to reveal a selection of amplitude scales.

 

dB - shows waveform levels in decibels, relative to digital full scale (it is the most common type of scale used for spectrum analyzers)

Normalized - shows waveform levels relative to the full scale level of 1.0

16 bit - shows waveform levels as quantization steps of a 16-bit audio format (-32768 to +32767)

Percent - shows waveform levels as percentage from full scale

 

Frequency Scale

You can also right-click on the frequency ruler to reveal a selection of different frequency scales:

 

Linear - Linear scale means that Hertz are linearly spaced on a screen.

Mel and Bark - Mel and Bark scale are frequency scales commonly found in psychoacoustics, i.e. they reflect how our ear detects pitch. They are approximately linear below 0.5 kHz and approximately logarithmic above that. Mel scale is reflecting our perception of pitch: equal subjective pitch increments produce equal increments in screen coordinate. Bark scale is reflecting our subjective loudness  perception and energy integration. It is similar to Mel scale, but puts more emphasis on low frequencies.

Log - In this mode, different octaves occupy equal screen space. The screen coordinates are proportional to the logarithm of Hertz down to 100 Hz.

Extended Log - This extends the logarithmic scale down to 10 Hz, so that it puts even more attention on lower frequencies.