Online Tone Generator
This free, easy to use digital tone generator opens in all the major browsers. It offers a treasure trove of tools for exploring the nature of sound without expensive mechanical frequency generators. To operate the basic tone generator, just enter the desired frequency and click Start. You can play four different waveforms: sine, square, sawtooth, or triangle. You can also generate two frequencies at once, use the program to tune your own string instruments, synthesizes voices with differing accents, generate beats, and check your own hearing. The "Pitch Shifter" tool lets you change the pitch of audio files (mp3 or wav) without affecting the tempo, while the "Time Shifter" lets you change the tempo of audio files without affecting pitch. CAUTION! If using headphones, set volume to LOW to prevent damage to your ears and/or to the audio equipment.
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Tomasz Szynalsky's Online Tone Generator
This tone generator was able to produce the purest tones we found among the free digital resources of its type. The user can change the frequency with a slider or change it more precisely by using a table of frequencies in Hz using the full range of musical pitches. The site would be especially useful for finding resonant frequencies of particular objects (like a wine glass), and using highly precise frequency notations to do calculations. You can also use it to tune a musical instrument with good accuracy.
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Physics Toolbox: Sensor Suite App
This free mobile-friendly app plays on all major devices in Android and iOS. The suite of tools includes an many sensors; those applicable to this Digi Kit are the oscilloscope, tone generator, sound meter, audio spectrogram, and tone detector. The app can be especially useful in conjunction with a sound meter to determine the inverse-square law for sound intensity, or with another tone generator to produce audible beats (by combining two tones of slight different frequencies).
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