In this experiment, you will analyze various common sounds. You will use a Microphone connected to a computer. The data-collection program will display the waveform of each sound, and will perform a Fast Fourier Transform (or FFT) of the waveform. The FFT tells you the amplitudes and frequencies of a collection of sine waves that, when added together, would sound the same as the original waveform.
In the first part of the experiment, you will study the sound of a tuning fork, which produces a tone composed mainly of a single frequency. Next, you will observe the production of overtones on a tuning fork. Overtones whose frequencies are multiples of the fundamental are called harmonic; other overtones are called inharmonic. You will also analyze the sound produced when you say two vowels.
In the last part of the experiment, you will be given a problem to solve. How does the telephone company know what numbers you dial?
Use a Microphone to analyze the frequency components of a tuning fork and your voice.
Record overtones produced with a tuning fork.
Examine how a touch-tone phone works.
Although telephone dialing tones, known as dual-tone multi-frequency (DTMF) tones, are commonly heard, it can be hard to produce these tones at will in the classroom. To make this easier, use the following twelve sample dialing tones, which are included on the CD with the book. Each sample plays a sustained note.
Sensors and Equipment
This experiment requires each of the following Vernier sensors and equipment (unless otherwise noted):
Step-by-step instructions for computer-based data collection
List of materials and equipment
Note: The experiment preview of the computer edition does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.