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Sonifying the Cosmic Microwave Background

Ryan McGee (PhD student, Media Arts and Technology), Jatila van der Veen (Department of Physics, UCSB), Matthew Wright (Media Arts and Technology), JoAnn Kuchera-Morin (Media Arts and Technology), Basak Alper (PhD student, Media Arts and Technology), Philip Lubin (Department of Physics, UCSB)

The Cosmic Microwave Background (CMB) is the oldest light that we can detect, having originated approximately 13.7 billion years ago, around 380,000 years after the so-called Big Bang singularity to which we trace the origin of our universe. Because the fluctuations in the CMB are the light echoes of the primordial sound waves that permeated the very early universe, it is natural to explore sonification as a means of teaching students and the public how we extract information about the universe’s physical properties from the power spectrum of the CMB. Just as the fundamental and higher harmonics of an instrument are determined by the physical properties of that instrument, the fundamental and higher harmonics of the CMB are controlled by the cosmological parameters that have shaped our universe, such as overall density, relative proportions of baryonic matter, dark matter, dark energy, and expansion history. Because our ears are more sensitive to audible frequencies than our eyes are to visual frequencies, the sonification makes apparent subtle differences than can not be perceived by data visualization alone. This work has also made the CMB data accessible to sight impaired students.

Turbulent Topologies

Screen shot of CMB sonification software running alongside the corresponding CMB visualization

The following sound examples were recorded directly from the output of the sonification software. In the first example we hear the transition from the raw noise of the CMB to the isolated partials. The second example transitions between multiple theoretical universe configurations.

Noise to Partials:

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Universe Transitions:

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This project was presented at the 2011 International Conference on Auditory Display (ICAD) in Budapest, Hungary, 2011.

Submitted paper (PDF):  Sonifying the Cosmic Microwave Background.

Abstract:  We present a new technique to sonify the power spectrum of the map of temperature anisotropy in the Cosmic Microwave Background (CMB), the oldest observable light of the universe. According to the Standard Cosmological Model, the universe began in a hot, dense state, and the first 380,000 years of its existence were dominated by a tightly coupled plasma of baryons and photons, which was permeated by gravity-driven pressure oscillations - sound waves. The imprint of these primordial sound waves remains as light echoes in the CMB, which we measure as small-amplitude red and blue shifts in the black body radiation of the universe, with a typical angular scale of one degree. With our software, users can observe how the temperature map and power spectrum of the CMB change in response to different compositions of baryonic matter, dark matter, and dark energy, and explore these different universes in "sound space". Our simulation is designed to enhance understanding of how we can infer properties of the universe from the power spectrum of CMB temperature anisotropies. We discuss the theory, the software, and potential applications in education.


Sonifying the CMB involved research collaboration between MAT and the UCSB Physics department.


The work was supported by NASA and the Planck Mission.

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