Can Sound Break Glass?

When you read the title you must not presume that I’m an expert  physicist. Though physics has always fascinated me, I chose a career which do not require physics in the main stream. So don’t expect this post to enlighten you with laws and theorems and authentically prove the facts.

Last year I was sharing a rented apartment with a friend. My land lady was so generous that she let us use all her furniture and her home appliances. Among them where an beautiful office table with a thin glass mounted atop wooden plank. The plank was a bit old with uneven shallow area in the middle. But the glass masked the defect and I was using it as a reading table.

I was using a HTC windows mobile which I had forgotten to switch on after a meeting that day. So, once I reached home, I pressed the power on button and placed it on the middle of the table and was keenly waiting for it to boot. 

The moment a welcome tone was heard, I was stunned by what I saw. The glass on which the phone rested, split into two starting from beneath the speaker. I could clearly see the crack appearing and then extending across along the entire breath of the glass.

Now that was fascinating. I called my room mate and explained what happened. He gave me strange looks as though I was cooking up something. Though not convinced, after seeing me struggle to persuade, he offered to believe me.

I called a few of my friends, whom I thought might give me a valid explanation. Like my room mate, many of them didn’t believe what I said,  some started laughing and some put the entire blame on the glass.

Then I moved on to the Internet and here is one of the videos that clarified things.

Internet sources say : When the frequency of the sound is equal or above the natural resonant frequency of the glass, it can break the glass. It is said that opera singers can break a wine glass by singing!