Waves With Higher Frequency

Short answer

• A wave with a higher frequency completes more cycles in each second than a lower frequency wave of the same kind. Frequency is measured in hertz, and one hertz means one cycle per second. When wave speed stays the same, a higher frequency wave has a shorter wavelength, because more cycles must fit into the distance the wave travels in one second. For light and other electromagnetic waves, a higher frequency also means more energy in each photon. For sound, a higher frequency usually means a higher pitch. Higher frequency does not by itself mean faster, louder, or stronger in every case, and the exact effect depends on the type of wave and the medium it travels through.

What Higher Frequency Means, in Plain Terms

Start with a rope tied at one end. If you shake the free end slowly, long waves travel along the rope and only a few crests pass a fixed point each second. If you shake the free end faster, the crests become closer together and more of them pass that point each second. The second case is the higher frequency wave. Nothing about the rope has changed except how fast you are driving it, yet the wave looks different and behaves differently.

Frequency counts cycles per second. Wavelength measures the distance between matching points on neighboring cycles, such as crest to crest or trough to trough. Period is the time for one complete cycle. Frequency and period are reciprocals of each other, so a higher frequency means a shorter period. A 2 hertz wave has a period of 0.5 seconds, because 1 divided by 2 equals 0.5. A 10 hertz wave has a period of 0.1 seconds, because 1 divided by 10 equals 0.1. The cycles arrive more often, and each cycle lasts less time.

OpenStax defines frequency for a wave as the number of waves passing a specific point per second, and wavelength as the distance between adjacent identical parts of a wave. Those two definitions are enough to understand most of what follows. When you hear that a wave has a higher frequency, ask two follow up questions. Higher than what, and in what medium? Frequency is always a comparison, and the medium often decides what else changes with it.

A useful mental image is a line of people passing through a gate. Frequency is how many people pass the gate each second. Wavelength is the spacing between one person and the next person in the line. If the line moves at the same speed but people pass the gate more often, they must be spaced more closely together. That is the core relationship between frequency and wavelength, and it applies across wave types whenever speed is held fixed.

Frequency, Wavelength, and Speed Move Together

The relationship that ties wave speed, frequency, and wavelength together is speed equals frequency times wavelength, written as v equals f times lambda. Here v is wave speed, f is frequency, and lambda is wavelength. OpenStax gives this relationship for waves in general and for sound in particular. The same relationship, with the speed of light in place of wave speed, applies to electromagnetic waves in a vacuum.

This formula explains why a higher frequency usually means a shorter wavelength. Suppose wave speed is fixed by the medium. If frequency goes up, wavelength must go down so that their product stays equal to the same speed. Double the frequency and the wavelength halves. Halve the frequency and the wavelength doubles. This is not a rule that someone chose for convenience. It follows from the definitions of frequency and wavelength and from the fact that speed is distance divided by time.

A worked check makes the point concrete. Take a wave traveling at 20 meters per second. At a frequency of 2 hertz, the wavelength is 10 meters, because 20 divided by 2 equals 10. At a frequency of 5 hertz, the same speed gives a wavelength of 4 meters, because 20 divided by 5 equals 4. At a frequency of 10 hertz, the wavelength is 2 meters, because 20 divided by 10 equals 2. The speed never changed. Only the balance between frequency and wavelength changed.

The companion article on how to calculate wave speed works through this formula in both directions, including how to rearrange it to find frequency or wavelength when the other two quantities are known. This article focuses instead on what a higher frequency means physically, and on how that meaning changes between sound, light, water waves, and other wave types.

Higher Frequency Does Not Automatically Mean Faster

One of the most common misunderstandings about waves with higher frequency is the idea that a higher frequency wave must travel faster. In many ordinary situations, that is not true. Wave speed is set mainly by the medium and its conditions, not by frequency alone. A higher frequency source can produce a wave that travels at the same speed as a lower frequency wave in the same medium, with a shorter wavelength to match.

Sound in air is a clear example. OpenStax states that sound speed in open air is nearly independent of frequency in the audible range, from 20 to 20,000 hertz. A high note and a low note played at the same time from the same place reach a listener at the same time, because both travel at nearly the same speed through the air. If high frequency sounds traveled noticeably faster, music heard from a distance would fall apart, with high notes arriving before low notes. That does not happen in ordinary listening, and the reason is that speed is nearly the same for both.

There are exceptions, and they matter. In a dispersive medium, speed does depend on frequency, so different frequencies travel at different speeds. Deep water waves are a well known example, where longer wavelength waves generally travel faster than shorter wavelength waves. Some materials also absorb or slow particular frequencies more than others. The safe general statement is therefore a careful one. Higher frequency means more cycles per second. Whether it also means a different speed depends on the medium, and in many textbook cases for sound in air and light in a vacuum, speed is treated as fixed while wavelength adjusts.

A second misunderstanding is the idea that higher frequency means louder or larger. It does not. Loudness for sound is tied mainly to amplitude, which is the size of the disturbance, not to how many cycles pass per second. A quiet high note and a loud low note can both exist. Frequency sets pitch for sound. Amplitude sets loudness. Mixing those two up leads to wrong predictions about both hearing and wave energy, as the next sections explain.

Higher Frequency in Sound: Pitch, Range, and Everyday Hearing

For sound, the most direct human experience of higher frequency is higher pitch. OpenStax states this plainly: for sound, a higher frequency corresponds to a higher pitch, while a lower frequency corresponds to a lower pitch, and amplitude corresponds to loudness. A soprano voice, a piccolo, and a small tweeter speaker all produce higher frequency sounds than a bass voice, a tuba, and a large woofer speaker. The instrument or speaker is not higher pitched by accident. Smaller vibrating parts tend to produce shorter wavelengths and higher frequencies, while larger parts tend to produce longer wavelengths and lower frequencies.

Normal human hearing covers frequencies from 20 to 20,000 hertz, according to OpenStax. Sounds below 20 hertz are called infrasound, and sounds above 20,000 hertz are called ultrasound. Neither is heard as ordinary sound by a typical human ear, although infrasound can sometimes be felt as vibration. Other animals hear different ranges. OpenStax notes that dogs can hear sounds as high as 30,000 hertz, while bats and dolphins can hear up to 100,000 hertz sounds. A dog whistle that sounds silent to a person can therefore be perfectly audible to a dog, because the whistle frequency sits above the human range but inside the dog range.

A worked example shows how wavelength changes across the audible range. Use the approximate speed of sound in air at 20 degrees Celsius, 343 meters per second. At 20 hertz, the wavelength is 343 divided by 20, which equals about 17 meters. At 20,000 hertz, the wavelength is 343 divided by 20,000, which equals about 0.017 meters, or 1.7 centimeters. The highest audible frequency has a wavelength roughly one thousand times shorter than the lowest audible frequency, even though both sounds travel through the same air at nearly the same speed. That thousandfold change in spacing is why small speakers handle high frequencies well and large speakers handle low frequencies well, and why high frequency sounds are more easily blocked by small obstacles while low frequency sounds bend around them more readily.

Musical pitch makes the same idea concrete. The note A above middle C is commonly tuned to 440 hertz. One octave higher, the same note name sounds at 880 hertz, exactly double the frequency. The wavelength in air halves, from about 0.78 meters at 440 hertz to about 0.39 meters at 880 hertz, using 343 meters per second for the speed of sound. The listener hears the higher note as higher in pitch, not as louder or faster. The doubling relationship also explains why octaves sound so similar despite the large frequency change: the wave pattern repeats twice as often, but its shape and musical role stay recognizable.

Ultrasound shows what lies beyond ordinary hearing. Medical and industrial uses of ultrasound rely on frequencies above 20,000 hertz, and the short wavelengths of those waves allow fine detail to be resolved in a small space. The physics point for this article is simpler. Ultrasound is not a different kind of wave. It is sound at a higher frequency than human hearing covers, with a shorter wavelength in the same medium and a pitch that, in principle, would be higher still if a listener could hear it.

Higher Frequency in Light: Color, the Spectrum, and Photon Energy

Electromagnetic waves need no material medium. NASA explains that mechanical waves, such as water waves and sound waves in air, travel through a medium by disturbing matter, while electromagnetic waves are changing electric and magnetic fields that can travel through the vacuum of space. All electromagnetic waves in a vacuum travel at the speed of light, so the frequency and wavelength relationship works the same way as for sound, with a fixed speed and a wavelength that shortens as frequency rises.

NASA defines frequency as the number of crests that pass a given point in one second, and wavelength as the distance between crests. Moving along the electromagnetic spectrum from long to short wavelengths, energy increases as wavelength shortens. That single sentence carries most of the physics of higher frequency light. Radio waves sit at the long wavelength, low frequency, low energy end. Gamma rays sit at the short wavelength, high frequency, high energy end. Visible light sits in between.

NASA gives approximate limits for each region of the spectrum. Radio waves have wavelengths longer than 0.1 meters and frequencies below 3 times 10 to the power of 9 hertz. Microwaves run from wavelengths of 0.001 meters to 0.1 meters and frequencies from 3 times 10 to the power of 9 hertz to 3 times 10 to the power of 11 hertz. Infrared runs from wavelengths of 7 times 10 to the power of negative 7 meters to 0.001 meters and frequencies from 3 times 10 to the power of 11 hertz to 4 times 10 to the power of 14 hertz. The optical, or visible, region runs from wavelengths of 4 times 10 to the power of negative 7 meters to 7 times 10 to the power of negative 7 meters and frequencies from 4 times 10 to the power of 14 hertz to 7.5 times 10 to the power of 14 hertz. Ultraviolet runs from wavelengths of 1 times 10 to the power of negative 8 meters to 4 times 10 to the power of negative 7 meters and frequencies from 7.5 times 10 to the power of 14 hertz to 3 times 10 to the power of 16 hertz. X-rays run from wavelengths of 1 times 10 to the power of negative 11 meters to 1 times 10 to the power of negative 8 meters and frequencies from 3 times 10 to the power of 16 hertz to 3 times 10 to the power of 19 hertz. Gamma rays have wavelengths shorter than 1 times 10 to the power of negative 11 meters and frequencies above 3 times 10 to the power of 19 hertz.

Those boundaries are approximate, and different sources draw them slightly differently. The ordering is what matters, and it does not change. Each step toward higher frequency shortens the wavelength and raises the energy carried by each photon. NASA notes that the spectrum boundaries are approximate limits, so a reader should not treat a boundary frequency as an exact dividing line in nature. A wave just above a boundary behaves almost exactly like a wave just below it.

Visible light gives the most familiar example of higher frequency. Red light sits at the low frequency end of the visible range, with longer wavelengths around 700 nanometers. Blue and violet light sit at the high frequency end, with shorter wavelengths around 450 nanometers for blue and shorter still for violet. A nanometer is 1 times 10 to the power of negative 9 meters. Using the speed of light in a vacuum, about 3.0 times 10 to the power of 8 meters per second, red light at 700 nanometers has a frequency of about 4.3 times 10 to the power of 14 hertz, while blue light at 450 nanometers has a frequency of about 6.7 times 10 to the power of 14 hertz. The blue wave completes roughly 1.6 times as many cycles per second as the red wave, and each blue photon carries more energy than each red photon. The companion article on the wavelength of visible light gives the visible range in more detail, and the companion article on what the electromagnetic spectrum is places visible light in the full spectrum.

Photon energy is where higher frequency light differs most sharply from higher frequency sound. For electromagnetic radiation, the energy of a single photon is given by E equals h times f, where E is photon energy, h is Planck constant, and f is frequency. OpenStax gives Planck constant as 6.626 times 10 to the power of negative 34 joule seconds. Because h is a constant, doubling frequency doubles photon energy. That is a direct proportionality, not a rough trend.

A worked example makes the scale concrete. Take green light at a wavelength of 550 nanometers. Its frequency is 3.0 times 10 to the power of 8 divided by 550 times 10 to the power of negative 9, which equals about 5.5 times 10 to the power of 14 hertz. Its photon energy is 6.626 times 10 to the power of negative 34 times 5.5 times 10 to the power of 14, which equals about 3.6 times 10 to the power of negative 19 joules. That is about 2.3 electron volts, using the conversion that one electron volt equals about 1.602 times 10 to the power of negative 19 joules. Now take an X-ray with a frequency of 3 times 10 to the power of 18 hertz, inside the NASA X-ray range. Its wavelength is 3.0 times 10 to the power of 8 divided by 3 times 10 to the power of 18, which equals 1 times 10 to the power of negative 10 meters, or 0.1 nanometers. Its photon energy is 6.626 times 10 to the power of negative 34 times 3 times 10 to the power of 18, which equals about 2.0 times 10 to the power of negative 15 joules, or about 12,400 electron volts. The X-ray photon carries thousands of times the energy of the green light photon, because its frequency is thousands of times higher in proportion.

That energy difference explains why higher frequency electromagnetic waves interact with matter differently. A radio photon carries so little energy that it passes through or reflects from ordinary materials without disturbing their atoms in the way an X-ray photon can. An ultraviolet photon carries enough energy to drive chemical changes in skin, which is why prolonged exposure to strong sunlight can damage skin even though visible light of similar brightness does not have the same effect. An X-ray photon carries enough energy to pass through soft tissue and reveal denser structures, which is the basis of X-ray imaging. The key caution is that total effect also depends on how many photons arrive, how long exposure lasts, and what material they meet. A single high energy photon is not the same as a large dose, and a bright low frequency beam can still carry a large total energy through sheer numbers of photons. Frequency sets energy per photon. Intensity, set by photon numbers and amplitude, sets how much total energy arrives.

Higher Frequency in Water Waves and Other Mechanical Waves

Water waves, waves on a string, and seismic waves are mechanical waves. They need a medium, and their speed is set by the properties of that medium, such as tension, density, stiffness, and depth. The frequency and wavelength relationship still holds in its basic form: speed equals frequency times wavelength. What changes is that speed itself can vary with frequency in some media, so the simple picture of fixed speed and shrinking wavelength needs a qualifier.

For a wave on a stretched string, OpenStax notes that speed depends on tension and on mass per unit length, not directly on frequency. Shake the string faster and you get a higher frequency wave with a shorter wavelength, traveling at the speed the string allows. For sound in air, speed is nearly independent of frequency across the audible range, as already noted. For deep water waves, the situation is different. Longer wavelength, lower frequency waves travel faster than shorter wavelength, higher frequency waves in deep water. A storm far out at sea therefore sends long swells that arrive ahead of shorter, choppier waves made by local wind, even though both are water waves. The general lesson is to check whether speed is fixed before assuming that a higher frequency must mean a proportionally shorter wavelength. In most introductory cases it does, but in dispersive media the speed itself shifts with frequency.

Energy in mechanical waves also needs care. For a wave on a string, OpenStax states that energy and power are proportional to the square of amplitude and the square of angular frequency. That means frequency does raise energy for that kind of wave, but amplitude matters just as much, and it is squared as well. A small amplitude, high frequency ripple can therefore carry less total energy than a large amplitude, low frequency swell. The statement that higher frequency means higher energy is exact for photon energy in electromagnetic waves, where E equals h times f. For mechanical waves, it is a tendency that holds when amplitude and medium are held fixed, not a universal law that overrides amplitude. Keeping that distinction prevents one of the most common overstatements in popular wave explanations.

Seismic waves add a further illustration. During an earthquake, different wave types travel at different speeds through rock, and their frequencies differ as well. OpenStax notes in its wave properties chapter that P waves in granite travel at 4 to 7 kilometers per second, while S waves travel at 2 to 5 kilometers per second, with both traveling faster in more rigid materials. The frequency of a seismic wave is set by the source motion, and its wavelength follows from speed and frequency in the material it passes through. A seismologist therefore cannot read frequency alone and know wavelength without also knowing the material and its wave speed.

How Frequency Changes, and How It Does Not

Frequency is set by the source. A tuning fork vibrating at 440 hertz produces sound waves at 440 hertz. A radio transmitter oscillating at a set frequency produces radio waves at that frequency. A shaking hand produces rope waves at the shaking frequency. When the wave enters a new medium, speed usually changes and wavelength usually changes with it, but frequency usually stays the same, because the source keeps driving the wave at the same rate and the boundary cannot create or destroy cycles. This is why a sound wave keeps its pitch when it passes from air into water, even though its wavelength lengthens because sound travels faster in water. The companion article on constructive and destructive interference explains what happens when waves meet and combine, which is a separate question from what sets their frequency in the first place.

Motion changes observed frequency, even when the source frequency stays fixed. This is the Doppler effect. When a sound source moves toward a listener, the waves are compressed in front of it and the listener hears a higher frequency than the source produces. When the source moves away, the waves are stretched out and the listener hears a lower frequency. The same effect applies to light, where motion toward an observer shifts light to higher frequencies and motion away shifts it to lower frequencies. The observed frequency changes because the spacing between successive waves changes for a moving observer, not because the source itself changed its vibration rate. Ambulance sirens give the familiar sound example, and astronomers use the light version to study the motion of distant stars and galaxies.

Heat transfer by radiation gives one more place where higher frequency waves appear in everyday physics, even when the word wave is not used. Radiation transfers energy by electromagnetic waves, and the companion article on radiation, convection, and conduction examples covers that transfer alongside conduction and convection. A hotter object emits more of its radiation at higher frequencies than a cooler object, which is part of why glowing metal shifts color as it heats. The frequency of the emitted radiation is tied to the energy of the source, not to a separate wave source that someone tuned by hand.

Worked Examples: Reading a Wave From Its Frequency

Example 1: Sound wavelength from frequency. A tone has a frequency of 1,000 hertz in air where the speed of sound is 343 meters per second. Its wavelength is speed divided by frequency, so 343 divided by 1,000 equals 0.343 meters, or 34.3 centimeters. A tone at 2,000 hertz in the same air has a wavelength of 343 divided by 2,000, which equals 0.1715 meters. Doubling frequency halved wavelength, exactly as the formula requires when speed stays fixed.

Example 2: Light frequency from wavelength. A violet light wave has a wavelength of 400 nanometers, which is 400 times 10 to the power of negative 9 meters. Its frequency in a vacuum is speed of light divided by wavelength, so 3.0 times 10 to the power of 8 divided by 400 times 10 to the power of negative 9 equals 7.5 times 10 to the power of 14 hertz. That sits at the top of the NASA optical range, at the boundary with ultraviolet. A small shift to a shorter wavelength would push the same calculation into the ultraviolet range, with a higher frequency to match.

Example 3: Photon energy from frequency. A microwave photon at a frequency of 3 times 10 to the power of 9 hertz, at the low end of the NASA microwave range, has an energy of 6.626 times 10 to the power of negative 34 times 3 times 10 to the power of 9, which equals about 2.0 times 10 to the power of negative 24 joules. That matches the NASA table, which places microwave photon energies from about 2 times 10 to the power of negative 24 joules upward. A visible light photon at 5.5 times 10 to the power of 14 hertz carries about 3.6 times 10 to the power of negative 19 joules, as calculated earlier, which is about 180,000 times more energy per photon. The comparison shows why frequency, not brightness alone, decides what a single photon can do when it meets matter.

Example 4: Checking a claim about frequency and speed. Suppose someone claims that doubling the frequency of a sound in air doubles its speed. The formula gives a quick check. If speed doubled and frequency doubled, wavelength would stay the same, because wavelength equals speed divided by frequency. But OpenStax states that sound speed in air is nearly independent of frequency in the audible range, so the premise fails. The correct result for ordinary air is that doubling frequency halves wavelength while speed stays nearly the same. Any claim that frequency alone sets speed should be tested against the medium first.

Common Mistakes When Comparing Waves

The first mistake is treating higher frequency as a synonym for faster. As shown above, speed is set by the medium in most ordinary cases, and frequency and wavelength adjust around it. The second mistake is treating higher frequency as a synonym for louder. Loudness follows amplitude for sound, and a high frequency tone can be quiet while a low frequency tone is loud. The third mistake is treating higher frequency as a synonym for more total energy without checking amplitude and photon count. For a single photon, higher frequency does mean higher energy. For a beam or a sound wave, total energy also depends on how many photons or how large the amplitude is.

The fourth mistake is assuming that a higher frequency wave always penetrates further or travels further. In many real materials, higher frequency waves are absorbed or scattered more strongly, so they may travel a shorter distance even though each photon or each cycle carries more energy. Low frequency radio waves can travel long distances and pass around obstacles, while higher frequency waves may be blocked more easily. The direction of the effect depends on the material, the frequency range, and the wave type, so no single rule covers every case. A reader should ask which material and which frequency range a claim is about before accepting it.

The fifth mistake is confusing frequency with wavelength in diagrams. Diagrams often draw a high frequency wave as a squashed, busy pattern and a low frequency wave as a stretched, calm pattern. That visual shorthand is correct for wavelength, but it can hide the fact that the two waves may have different amplitudes as well. Two waves drawn with the same height but different spacing differ in frequency and wavelength, not in amplitude. Two waves drawn with different heights differ in amplitude, whatever their spacing. Reading a diagram means checking both spacing and height separately.

Frequently Asked Questions

What is a wave with a higher frequency?

It is a wave that completes more cycles per second than the wave it is being compared with. Its frequency in hertz is larger, its period is shorter, and, when wave speed is fixed, its wavelength is shorter.

Does a higher frequency wave have a shorter wavelength?

Yes, when wave speed stays the same. Speed equals frequency times wavelength, so a larger frequency must pair with a smaller wavelength to give the same speed. If speed changes, as in a dispersive medium or a new material, the wavelength change is smaller or larger than the simple fixed speed case, but the formula still applies with the new speed.

Does higher frequency mean higher energy?

For light and other electromagnetic waves, each photon carries more energy at a higher frequency, following E equals h times f. For mechanical waves such as sound and water waves, energy also rises with frequency when amplitude is held fixed, but amplitude matters too, so a small high frequency wave can carry less total energy than a large low frequency wave.

Does higher frequency mean higher pitch?

For sound, yes. Pitch is the perception of frequency, so a higher frequency sound is heard as higher pitched. Loudness is separate and follows amplitude, so pitch and loudness can change independently.

Is a higher frequency wave always more dangerous?

No. Danger depends on photon energy, total dose, exposure time, and the material involved, not on frequency alone. Higher frequency electromagnetic waves carry more energy per photon, and at ultraviolet, X-ray, and gamma ray frequencies that energy is enough to drive chemical changes or pass through tissue in ways that lower frequency waves do not. But a weak high frequency source and a strong low frequency source cannot be compared by frequency alone, and this article makes no medical claim about any particular exposure. Anyone concerned about a specific exposure should follow guidance from a qualified health or safety authority, not a general wave explanation.

Can frequency change when a wave enters a new medium?

Usually it does not. The source sets the frequency, and the wave keeps that frequency as it crosses into a new medium, while speed and wavelength change to fit the new medium. Observed frequency can change with motion of the source or observer, which is the Doppler effect, but that is a change in what is observed, not a change in what the source produces.

What is the highest frequency wave?

There is no single highest frequency in principle, because the electromagnetic spectrum extends beyond gamma rays to still higher frequencies, and the boundaries between regions are approximate. In practice, the highest frequency waves people meet in ordinary explanations are gamma rays, with frequencies above 3 times 10 to the power of 19 hertz in the NASA table. Higher frequencies than that are studied in particle physics and astrophysics, but they are not part of everyday wave examples.

How can I tell a higher frequency wave from a lower frequency wave in a diagram?

Count cycles in a fixed distance. The wave with more cycles in the same distance has the shorter wavelength and, if both waves travel at the same speed, the higher frequency. Also check amplitude separately, by looking at wave height, so that a tall low frequency wave is not mistaken for a high frequency wave.

Sources & references

• NASA Science, Anatomy of an Electromagnetic Wave. Opened and read 3 November 2026. Mechanical waves need a medium, electromagnetic waves do not; frequency is the number of crests passing a point in one second; wavelength is the distance between crests; moving from long to short wavelengths, energy increases as wavelength shortens. Link: https://science.nasa.gov/ems/02_anatomy/
• NASA, Imagine the Universe, Wavelength, Frequency, and Energy. Opened and read 3 November 2026. Approximate wavelength, frequency, and energy limits for radio, microwave, infrared, optical, ultraviolet, X-ray, and gamma ray regions, as used for the spectrum ranges in this article. Link: https://imagine.gsfc.nasa.gov/science/toolbox/spectrum_chart.html
• OpenStax Physics, Section 13.2 Wave Properties: Speed, Amplitude, Frequency, and Period. Opened and read 3 November 2026. Frequency as waves passing a point per second; wavelength as distance between adjacent identical parts; v equals f times lambda; in a medium where speed is constant, higher frequency means smaller wavelength; for sound, higher frequency means higher pitch and amplitude means loudness; sound speed in air nearly independent of frequency; seismic P wave and S wave speeds in granite. Link: https://openstax.org/books/physics/pages/13-2-wave-properties-speed-amplitude-frequency-and-period
• OpenStax College Physics, Section 17.2 Speed of Sound, Frequency, and Wavelength. Read via search result 3 November 2026. Sound speed nearly independent of frequency in the audible range of 20 to 20,000 hertz; high pitch means small wavelength; small instruments make high pitch sounds and large instruments make low pitch sounds. Link: https://openstax.org/books/college-physics/pages/17-2-speed-of-sound-frequency-and-wavelength
• OpenStax College Physics, Section 17.6 Hearing. Read via search result 3 November 2026. Normal human hearing 20 to 20,000 hertz; below 20 hertz infrasound, above 20,000 hertz ultrasound; dogs hear up to 30,000 hertz, bats and dolphins up to 100,000 hertz; perception of frequency is pitch. Link: https://openstax.org/books/college-physics-2e/pages/17-6-hearing
• OpenStax College Physics, Chapter 29 Section Summary. Read via search result 3 November 2026. Photon energy E equals h times f; Planck constant h equals 6.626 times 10 to the power of negative 34 joule seconds; photon energy responsible for many characteristics of electromagnetic radiation, particularly noticeable at high frequencies. Link: https://openstax.org/books/college-physics/pages/29-section-summary