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Old 11-08-2018, 10:08 PM
Chouchou Chouchou is offline
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Default What does waveform stand for?

Hi, I am a ProTools 12 user. I have a very simple question. I usually edit my own live recordings looking at the waveform. Does anyone help me understand what waveform means? My understandings are that the waves are volume of the sound source, and has nothing to do with frequency data. Then my question, if I am correct, is why waves have plus and minus values? Thank you in advance!
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Old 11-08-2018, 10:26 PM
BScout BScout is offline
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Default Re: What does waveform stand for?

Quote:
Originally Posted by Chouchou View Post
My understandings are that the waves are volume of the sound source, and has nothing to do with frequency data.
No. Waveforms show amplitude ("volume") and frequency (which is cycles per second).

The length of the wave dictates pitch. Or as we express it: Hertz (which is how many waves fit in a second)

If you want a better understanding, pull up the signal generator plugin and record a sine wave at different pitches and and different volumes. Then zoom in and see how the waveforms differ.
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Old 11-09-2018, 11:24 PM
Chouchou Chouchou is offline
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Default Re: What does waveform stand for?

[QUOTE=BScout;2505180]No. Waveforms show amplitude ("volume") and frequency (which is cycles per second).The length of the wave dictates pitch.

Thank you for your message. I understood the amplitude is the volume and alternating wave shapes are a summation of waves of different frequencies in cases like an orchestra sounds. Then I have the other question. Why does the wave form has minus values when it is the volume and frequency? There should not be minus values in volume. It may be an inverted plus values to reflect the frequency data. Am I correct?
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Old 11-09-2018, 11:47 PM
BScout BScout is offline
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Default Re: What does waveform stand for?

Waveforms are an oscillation of energy. You misunderstand what the negative/positive mean. Waveforms move between nodes and antinodes. Antinodes being the amplitude (both in positive and negative) from the zero crossing (the node). There is no "negative energy" to a waveform.

Amplitude (volume) is the absolute value.

Frequency, once again, is the oscillation (cycles) per second. The number of the cycles per second is the frequency. So, no, you are not correct. You obviously have not taken my recommendation to record some sine waves with the signal generator plugin to look at what happens. Record a 1kHz sine wave at -20dB and then record a 10kHz and 100kHz at -20dB. Compare the three by looking at the zoomed in clips in Pro Tools. Then adjust volume level of the same 3 frequencies and record them as clips and see what happens compared to your first three. You'll see the higher frequency shows the waves more compressed but the peaks and dips the same at the same volume. When you change the volume, you'll see both the peaks and dips get more exaggerated (higher and lower.)

And no, the alternating wave shapes are not "summation of waves of different frequencies in cases like an orchestra sounds." All waves alternate even pure tones.

I think you might need to understand some basic mechanical physics to understand how sound moves to understand these representations.
The most basic physical representation of a wave is a ripple in water. Note how it moves up and down. That is your negative/positive when at the lowest/highest. when there's the in-between point, that is your node (zero crossing.)
Or look at a string and strum it. Note how it moves up and down. Same thing. A higher pitched note will vibrate the string faster (more cycles per second) by shortening the string length (which controls where the nodes are of the wave -- which is what frets do on a guitar. In essence that makes a smaller wavelength.)
A louder note (strumming harder) will have the string flex higher and lower. Lower is not negative just the opposite of the upward movement.

Obviously on a forum, I have no idea age/education etc. so hopefully this is helpful to you and not under/over your head:
https://www.khanacademy.org/science/...aves-and-sound
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Last edited by BScout; 11-10-2018 at 12:33 AM. Reason: clarification of experiment
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