# Why is it that the fundamental harmonic is louder than rest?

• I

## Main Question or Discussion Point

Why is it that the fundamental harmonic is louder than rest? If energy is the same as frequency surely the greater the harmonic the louder it is.

Also what does amplitude represent in waves?

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DrClaude
Mentor
If energy is the same as frequency
It's not.

Also what does amplitude represent in waves?
The maximum distance between peaks and troughs, measured parallel to the direction of oscillation.

And the fundamental does not have to be the loudest. You can excite the system such that the higher harmonics have larger amplitudes. Even with zero amplitude for the fundamental.
However the damping usually increases with frequency and after some time after the excitation, the higher harmonics die faster and the fundamental may dominate.

• Biker
Why is it that the fundamental harmonic is louder than rest?
Your question prompted me to do some reading and it turns out that it's not always the case e.g. for some musical instruments such as the trumpet the higher harmonics have a larger amplitude.

I think that the fundamental is called that because it's the one you hear. If there are lower frequencies present and they are lower amplitude than the fundamental, they are called sub-harmonics. The amplitude is representative of the loudness, although loudness is a psychological phenomena in some cases.

The term fundamental has nothing to do with loudness. It is the lowest frequency mode of the system. The sub harmonics have lower frequencies. Amplitudes are not relevant for these definition.

• davenn
sophiecentaur
Gold Member
I think that the fundamental is called that because it's the one you hear.
It's not always. However, the overtones of any standing wave are usually the highest amplitude. The way the oscillations are matched to the air can bring out higher order overtones out more. I use the term Overtone because the higher orders may be far from harmonics. Brass instruments can be waaay out without the player pulling notes. But it's what we find pleasing.

• Theudius
I was told by my physics lecturer energy is the same as frequency, if this is not the case what is energy represented by in a wave?

sophiecentaur
Gold Member
I was told by my physics lecturer energy is the same as frequency, if this is not the case what is energy represented by in a wave?
What he was referring to was Quantum Mechanics. In particular, the formula
E = hf tells you the energy of a photon.

I was told by my physics lecturer energy is the same as frequency, if this is not the case what is energy represented by in a wave?
As sophiecentaur points out, the energy of a photon is proportional to the frequency of the light. The number of such photons determines the total energy at that frequency.

Why is it that the fundamental harmonic is louder than rest? If energy is the same as frequency surely the greater the harmonic the louder it is.

Also what does amplitude represent in waves?
what kind of system are you referring to?

ZapperZ
Staff Emeritus
I was told by my physics lecturer energy is the same as frequency, if this is not the case what is energy represented by in a wave?
You need context. While energy can be related to energy, it is NOT the ONLY factor when considering the energy of a classical wave. The amplitude of the wave also affects the energy. So your physics lecturer is correct. However, you understood it as it being the only factor affecting energy.

Zz.

• Theudius
He used it to explain how wavelength and wave speed change yet the frequency stays the same when light enters a medium. He stated frequency is energy and energy is conserved.

ZapperZ
Staff Emeritus