100 Things #51: Flexible Options for Scaling WAV Files

SoundCheck offers multiple ways to work with WAV files; normalize to peak, scale to sound card values, and user defined scaling. Normalizing to peak ensures the waveforms take advantage of as much headroom as is available. Scaling to sound card values is perfect for working with multiple WAV files, making multi-channel measurements and data manipulation easy and reliable. For increased functionality with external programs like MATLAB, WAV files can be scaled to a user defined level, all from within SoundCheck.

Scaling WAV files in SoundCheck

Learn more about Scaling WAV files in SoundCheck

The most comprehensive information on this subject can be found in the SoundCheck Manual (Page 367 in the SoundCheck 21 manual)


Video Script: Flexible Options for Scaling WAV files

It’s often necessary to use multiple audio processing software programs in test and measurement applications. SoundCheck’s scaling options make it easy to manipulate audio files between packages while retaining maximum data integrity. For example, you might acquire audio files using another device and need to process them in SoundCheck. Or conversely, you may want to take SoundCheck-acquired data and import it into MatLab for additional analysis.

SoundCheck uses a proprietary binary file format for handling audio files, .wfm, which is a digital amplitude vs time representation of analog audio. This format is advantageous as it saves the metadata, such as units, scaling factors etc, along with the data. However, SoundCheck also supports the widely used .wav format, including multichannel wav files, for easy data transfer between programs.

It’s important when transferring files between systems to ensure that they are correctly scaled and to understand how they are scaled. SoundCheck offers a variety of options.

Normalizing a WAV to peak (FSD) saves the waveform so that the peak value of the waveform is 100% full scale, regardless of the actual level of the waveform. This ensures that when you’re saving recordings to be played back out of a different system, you’re using as much head-room as possible, therefore maximizing signal-to-noise ratio. However, the absolute calibration in physical units, for example, V or Pa are lost.

If you’re working with multiple files and need to retain the differences in level between them you can scale them to the sound card Vp value. This lets you save them as wav files, but retains the relative difference in level between them and will play the wav files back at the same level when using the same sound card.

You can also save the waveform relative to a user defined maximum level of physical units which can be useful if you are exporting data to be used in other tools such as MATLAB.

You have similar options when you’re importing a WAV file into SoundCheck.  SoundCheck prompts you to select either the units of Full Scale  where the max amplitude of digital sine wave is -3dB or the AES 17 Full Scale option,  where the max amplitude is 0dBFS.

So, as you can see, there are various options for both saving and opening wav files, giving you the flexibility you need for exchanging soundCheck files with other programs while maintaining data integrity. More detailed information is available in the SoundCheck manual.