SOUNDS OF SPACETIME
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About GW Sounds

(What you need to know before listening)

Gravitational waves are not sound.

You can't hear them. But many of their properties are similar to sound waves. For example, photons are produced by atomic-scale particles and processes (e.g., electron transitions in an atom). Gravitational waves (GWs) are produced by the bulk motion of massive objects (two black holes orbiting each other; large-scale convection in a supernova). Think of a struck drum, bell, or guitar string--the sound comes from the large-scale motion of the material, not an atomic-scale vibration. Photons are easily absorbed, scattered, or reflected. But GWs easily propagate through most materials--just like sound. This is why it is useful to convert gravitational-wave signals to sound waves. This is not unique to GWs. Radio waves can be converted to sounds waves (this is what your radio does). And one can also go in the other direction: take a sound wave and make a picture of it (like I did with this recording of my voice): 
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The sounds you hear will depend on your speakers.

We can't play for you any gravitational wave. This is because the human ear can only hear frequencies between 20 Hz and 20,000 Hz (20 kHz; Hz = Hertz = 1 cycle/second). In principle, gravitational waves can be produced at any frequency. In practice, we don't expect to find gravitational-waves much above 50 kHz. However, there are potentially detectable gravitational waves with nHz frequencies or smaller. Here, we'll focus on GWs with frequencies corresponding to the range of human hearing. By coincidence, this range corresponds nicely with the actual frequency range that the LIGO detectors are sensitive to (GWs between 10 Hz and 10 kHz). Other detectors (like eLISA or pulsar timing) can detect GWs at much lower frequencies. 

The sounds you can hear are also constrained by your speakers. Laptop speakers can typically play sounds in the range 120 Hz - 16 kHz. With earphones or a subwoofer connected to your computer you'll be able to hear sounds from 30 Hz to 16 kHz.  When playing the sounds, you might not hear anything initially if your speakers can't play sounds at low frequencies. We'll usually indicate if a sound has significant low-frequency components (use earphones or a subwoofer to hear those). [You can test what frequency range your device can produce via this website or this one.]

To download our sounds: our current audio players don't have a simple download button. Use the following work-around instead: go to the page with the sounds you want. Right click on your browser and select "view page source." From there search for ".mp3" and click on the link corresponding to the sound you want (or save the link target to your computer).
soundsofspacetime.org
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