Using Light to Transmit Sound Directly to the Receiver’s Ear

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Communication has come a long way but this is about to blow your mind. Researchers at the MIT have discovered a way to transmit audio to a particular person’s ear by using a laser to direct a modulated beam of light at the ear.

Before now, researchers in sound and optics have been working on a way to transmit audio over the air directly to a receiver’s ear, doing so where the receiver lacks a piece of communication equipment.

This was first proposed by Graham bell but for the first, it has been put to use properly and safely by researchers at the MIT.

The authors of the work published in OSA Optics Letters demonstrate how sound can be transferred safely to a particular person over a specified distance, in a system where the receiver hears clear audio without the need for a piece of receiving equipment.

Man on earphone
No need for earphones man (Image source: Pexels)

The system is so good that messages sent over specific distances can only be received at the specified distance. Even if someone cuts across the beam of light, they won’t hear the audio.

How Audio Is Transmitted Using Light

In this amazing discovery, the audio message to be transmitted is encoded upon a modulated laser beam and sent to the ear of the receiver through photoacoustic effects.

The photoacoustic effect involves the formation of sound waves following the absorption of light in a material sample. Since there is always some vapour in the air, the encoded sent as an optical signal is converted into audible signal as the light is absorbed by ambient water vapour available near the receiver’s ear.

Once the signal is converted, the audible signal is transmitted to the ear by airborne acoustic transmission. This removes the need for the receiver to use any audio equipment to receive and convert the signal.

The researchers were able to record speech and musical audio and transmit it safely using a laser in a process termed “photoacoustic communication.” (I love technology!)

This new communication system includes the use of both traditional photoacoustics and dynamic photoacoustics to transmit audio using a laser.

The dynamic photoacoustics involved sweeping a laser beam at the speed of sound.

Doing this at a wavelength absorbed by water is an efficient way of transmitting sound with higher audio – the traditional technique does not involve sweeping the laser beam. Any other difference between the two?

Yes. While traditional photoacoustics delivered sound with greater fidelity, the laser sweeping technique delivered sound with higher audio.

Related: Selecting a Surround Sound System


And the entire transmission can be done safely. It is well known that light from a laser could cause damage to the eye and skin. However, using traditional photoacoustics, the researchers are able to use lasers to send audio without causing damage to the eye and skin in any setting.

Source: Optical Society of America - OSA Publishing
Visit DOI: 10.1364/OL.44.000622
 for the complete paper
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