FREQUENCY AND SOUND

Here are a few examples of beeps you might hear during a normal day: The microwave oven beeps when it’s done cooking your food. The cell phone plays different tones of beeps that resemble songs to get your attention when a call is coming in. The ATM machine beeps to remind you not to forget your card. A store cash register beeps to let the teller know that the bar code of the grocery item passed over the scanner was read. Many calculators beep when the wrong keys are pressed. Let’s not forget that you may have started your day with a beeping alarm clock.

MICROCONTROLLERS, SPEAKERS, BEEPS AND ON/OFF SIGNALS

Just about all of the electronic beeps you hear during your daily routine are made by microcontrollers connected to speakers. The microcontroller creates these beeps by sending rapid high/low signals to various types of speakers. The rate of these high/low signals is called the frequency, and it determines the tone or pitch of the beep. Each time a high/low repeats itself, it is called a cycle. You will often see the number of cycles per second referred to as Hertz, and it is abbreviated Hz. For example, one of the most common frequencies for the beeps that help machines get your attention is 2 kHz. That means that the high/low signals repeat at 2000 times per second.

THE PIEZOSPEAKER

When a guitar string vibrates, it causes changes in air pressure. These changes in air pressure are what your ear detects as a tone. The faster the changes in air pressure, the higher the pitch, and the slower the changes in air pressure, the lower the pitch. The element inside the piezospeaker’s plastic speaker case is called a piezoelectric element.