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Analytical Chemistry

The Sound Of Spectra

Educators convert infrared data into sound files, giving chemists with limited vision a new tool

by Craig Bettenhausen
August 5, 2013 | A version of this story appeared in Volume 91, Issue 31

CORRECTION: This story was updated on Oct. 10, 2013, to correct the structure of butanoic acid; the previous incorrect structure was of pentanoic acid.
Butanoic Acid
Early in the audio version of this spectrum, the O–H stretch of butanoic acid can be heard. A little later, the C=O stretch is distinguishable, followed by a variety of peaks in the spectrum’s fingerprint region.
Credit: J. Chem. Educ.
Try to identify the key functional groups in these audio spectra.

The marimba is rarely called for when analyzing chemical data. But it is the instrument of choice for a team of educators who have adapted infrared spectra into an audio format for use by visually impaired scientists and students (J. Chem. Educ. 2013, DOI: 10.1021/ed4000124). Florbela Pereira, Joao Aires-de-Sousa, and coworkers at the New University of Lisbon used open-source software—available on their MOLInsight project page—to convert IR data to MIDI format, a type of digital music file. The magnitude of the IR peaks, normally the y axis in spectra, is represented by the pitch, with a higher note indicating a stronger signal. The frequency, normally the x axis, is represented by time. After some training, a group of visually impaired students were able to correctly identify the main functional groups represented in sample spectra and use that information to identify organic molecules. The software could be easily extended to other types of spectra. One student, Sérgio Neves, says the approach “allows me to summarize the spectral data into a small audio graphic, providing a more global overview of the spectrum.”


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