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Learn how to use LabVIEW to retrieve an audio signal from a WAV-format file, and how to save an audio signal that you have createdto a WAV-format file.

Overview

LabVIEW offers a variety of ways to read and write audio files in WAV format. After completing this module you will be able to use the Simple Read and Simple Write subVIs located in the “Programming | Graphics&Sound | Sound | Files” palette to retrieve an audio signal as a 1-D array from a .wav file, and also to save a 1-D array that represents an audio signal to a .wav file. Additional points covered include scaling your audio signal to have a maximum absolute value of one before saving as an audio file, and how to create a two-channel (stereo) audio file.

Retrieve an audio signal from a .wav file

The Sound File Simple Read subVI accepts a filename for an audio file in .wav format and returns a waveform data type. You can read mono or stereo files, and also determine information such as the audio signal’s sampling frequency and its total number of samples.

The following video screencast shows how to use Simple Read to retrieve the audio signal as an array data type that can be used as a signal input for your own VIs. You may want to start LabVIEW now, then follow along to create your own version of the VI pictured below. If so, you will need the two audio files referenced in the screencast: tone-noise.wav and left-right.wav .

[video] LabVIEW Techniques: Retrieve an audio signal from a .wav file

Save an audio signal to a .wav file

The Sound File Simple Write subVI accepts a signal in waveform data type and a filename and stores the signal as a .wav file. You can set the number of bits per sample (16 is recommended for best fidelity). You must ensure that your signal values lie in the range -1 to +1, otherwise other applications may not be able to read your .wav file properly.

The next video screencast shows how to use Simple Write to save an existing 1-D array that represents an audio signal to a .wav file. The screencast also covers some not-so-obvious data-type transformations required to successfully create your .wav file. You may want to start LabVIEW now, then follow along to create your own version of the VI pictured below. If so, you will need the audio file referenced in the screencast: tone-noise.wav .

[video] LabVIEW Techniques: Save an audio signal to a .wav file

Scale your audio before saving to a .wav file

As mentioned earlier, you must ensure that all of the samples in your signal lie in the range -1 to +1. It is easy to create signals that exceed this range, especially when you add multiple signals together.

The next screencast illustrates how Quick Scale is an easy way to scale your 1-D array such that the maximum absolute value is always one; Quick Scale is located in the “Signal Processing | Sig Operation” palette, and should be used as the last step before converting to the waveform data type.

[video] LabVIEW Techniques: Scale audio signal to +/- 1 range beforesaving to a .wav file

Create a two-channel (stereo) .wav file

Creating a stereo .wav file requires that you assemble an array of waveforms, one for the left channel and the other for the right channel. Watch the next screencast video to learn how.

[video] LabVIEW Techniques: Save a stereo (two-channel) audio signalto a .wav file

Questions & Answers

Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
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I only see partial conversation and what's the question here!
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what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
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What is meant by 'nano scale'?
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What is STMs full form?
LITNING
scanning tunneling microscope
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if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
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analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
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research.net
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Source:  OpenStax, Musical signal processing with labview -- programming techniques for audio signal processing. OpenStax CNX. Jul 18, 2007 Download for free at http://cnx.org/content/col10440/1.1
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