I am sitting in a cigar lounge, and under the jazz music playing I can hear this strange, rising and falling tone, that sounds similar to one of those weird tubes you can find at a fun fair. You tilt the tube this way, and tip it that way, and a weight moves in the tube and creates a weird tube sound. The pitch seems generally to descend or ascend (with some local irregularities) depending on which direction the pipe is tilted and what it's previous state was.
The guy packing boxes in the corner with the adhesive packing tape seems to be creating a sound similar to this as he draws out long sections of tape from the roll.
I am wondering if there is a physical explanation for the sound made by the dispensing of packing tape, and what this explanation would be?
Best Answer
The adhesive on tape is a viscoelastic material. I think popular brands like Sellotape use a low molecular weight synthetic rubber like polyisobutylene.
Anyhow, as you peel the tape away from the roll the adhesive stretches until the tension in it is greater than adhesion to the top of the tape below it, then it breaks free. As it breaks away, the stretched adhesive relaxes and the tension is released. As you continue pulling, the next bit of adhesive starts stretching until it too suddenly pulls free, and the cycle is repeated. This means that as you pull the tape off the roll it comes free from the roll in a series of jerks. If the frequency of the jerks is in the audio range, say 50 times a second or greater, you'll hear it as an audible tone.
The faster you pull then tape off the roll the higher the frequency of jerks will be. This is partly because the adhesive will only stretch a certain distance before pulling free, so a higher velocity of tape removal requires more jerks per second. However it's also because the elastic properties of the tape are frequency dependant and it becomes less elastic at higher peeling speeds.
If you're interested in pursuing this further I found a paper analysing the dynamics of tape peeling here.