# Audio Frequency signal

Joined Feb 4, 2022
127
I am trying to understand the use of audio frequencies. Frequency is measured in Hertz (Hz), I see that the graph of the signals drawn in one axis shows the frequency and the other shows the time. I don't understand what is the use of measuring signal by frequency.

I see that microphone converts audio signal into voltage signal. The processor takes the voltage signal and processes it. and a display device shows the frequency of the signal. I do not understand why we have to measure the frequency, what are its benefits?

#### Papabravo

Joined Feb 24, 2006
18,432
I am trying to understand the use of audio frequencies. Frequency is measured in Hertz (Hz), I see that the graph of the signals drawn in one axis shows the frequency and the other shows the time. I don't understand what is the use of measuring signal by frequency.

I see that microphone converts audio signal into voltage signal. The processor takes the voltage signal and processes it. and a display device shows the frequency of the signal. I do not understand why we have to measure the frequency, what are its benefits?
Convenience

#### MrChips

Joined Oct 2, 2009
26,134
Time is a human construct.
Frequency is natural.
How many times did the sun rise this year?

#### Papabravo

Joined Feb 24, 2006
18,432
Time is a human construct.
Frequency is natural.
How many times did the sun rise this year?
Lemme see. Not a leap year. So 31 + 28 +14 = 73!

#### Ya’akov

Joined Jan 27, 2019
5,668
Audio signals are characterized by their frequency. The Fourier Transform decomposes an audio signal into its component frequencies which when added together comprise the signal we hear. Since frequency is the foundation of audio and radio signals it makes sense to use that instead of period or wavelength, which are sometimes useful, because to use the information in those forms you’d almost always find yourself converting to frequency.

In some areas, like light, wavelength is used because it is the most generally useful way to characterize it for practical use.

#### Papabravo

Joined Feb 24, 2006
18,432
Audio signals are characterized by their frequency. The Fourier Transform decomposes an audio signal into its component frequencies which when added together comprise the signal we hear. Since frequency is the foundation of audio and radio signals it makes sense to use that instead of period or wavelength, which are sometimes useful, because to use the information in those forms you’d almost always find yourself converting to frequency.

In some areas, like light, wavelength is used because it is the most generally useful way to characterize it for practical use.
To sum it up. Convenience.

#### Audioguru again

Joined Oct 21, 2019
4,693
The frequency of a sound is the musical "pitch" plus harmonic frequencies from very low to very high.
Most humans can hear from 20Hz (20 waves per second) to 20kHz (20 thousand waves per second).

Home electricity is 50Hz in some countries or is 60Hz in other countries.

#### Ya’akov

Joined Jan 27, 2019
5,668
Yes, but I figured it was worth showing the work since it seemed the figures to be summed were not evident to the TS.

#### MrChips

Joined Oct 2, 2009
26,134
Lemme see. Not a leap year. So 31 + 28 +14 = 73!
Sorry, I should have said "this past year".

#### MrSalts

Joined Apr 2, 2020
1,762
I am trying to understand the use of audio frequencies. Frequency is measured in Hertz (Hz), I see that the graph of the signals drawn in one axis shows the frequency and the other shows the time. I don't understand what is the use of measuring signal by frequency.

I see that microphone converts audio signal into voltage signal. The processor takes the voltage signal and processes it. and a display device shows the frequency of the signal. I do not understand why we have to measure the frequency, what are its benefits?
Look at the back of your appliances, the plate near the cord uses the Hz symbol. Look at the face of your radio dial, it uses the kHz (AM) and/or MHz (FM). Your WiFi router says 5GHz, your PC says 2.4GHz. The update frequency on your display is 120Hz.

Do you really have such a general question like, "what are the benefits" when you see the important unit if measure on devices around you? Or do you have a more specific question?

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#### MrChips

Joined Oct 2, 2009
26,134
I am trying to understand the use of audio frequencies. Frequency is measured in Hertz (Hz), I see that the graph of the signals drawn in one axis shows the frequency and the other shows the time. I don't understand what is the use of measuring signal by frequency.

I see that microphone converts audio signal into voltage signal. The processor takes the voltage signal and processes it. and a display device shows the frequency of the signal. I do not understand why we have to measure the frequency, what are its benefits?
When you strike a bell you hear frequency, not time.

#### MrSalts

Joined Apr 2, 2020
1,762
Sorry, I should have said "this past year".
Weird that such detail has to be specified if "frequency is natural". How many times did the sun rise in the past hour?

#### MrChips

Joined Oct 2, 2009
26,134
Weird that such detail has to be specified if "frequency is natural". How many times did the sun rise in the past hour?
Hour is a human construct. Year is not.

The sun rose 365 times in the past year.

#### MrSalts

Joined Apr 2, 2020
1,762
Hour is a human construct. Year is not.

The sun rose 365 times in the past year.
And that is Important because...

#### BobTPH

Joined Jun 5, 2013
4,927
Time is a human construct.
Frequency is natural.
How many times did the sun rise this year?
How do you define frequency without time?

Bob

#### MrChips

Joined Oct 2, 2009
26,134
How do you define frequency without time?

Bob
365 times each year is frequency.

#### Audioguru again

Joined Oct 21, 2019
4,693

My oscilloscope and my multimeter show audio frequency numbers and my hearing can detect some harmonics.

#### Ya’akov

Joined Jan 27, 2019
5,668
When an orchestra tunes up their reference is a A. In particular the A that is 400Hz.

We call it a “440 A”. We could call it a “779.545mm@20°C A”, or a “2.2727ms A” but somehow it seems that the frequency is much more cogent. A tuning fork can tell you if you have the note right because it has a resonant frequency that matches. I think using a ruler or clock would be harder.

Of course this is silly but it is just more practical evidence for using frequency which flows from the nature of oscillating systems.

#### MrChips

Joined Oct 2, 2009
26,134
The ear is a frequency receptor, not a time receptor.
The ear responds to 1kHz, not 1ms.

#### Ian0

Joined Aug 7, 2020
5,161
Frequency is measured in Hertz (Hz), I see that the graph of the signals drawn in one axis shows the frequency and the other shows the time.
That would just be graph of y=1/x
I've seen voltage vs. time, voltage vs. frequency but never time vs. frequency