Understanding Audio Frequency Spectrum

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Understanding Audio Frequency Spectrum

When you go to watch a movie or listen to your favorite music, the last thing you think of is the audio frequency spectrum. However, this plays a crucial role in your enjoyment of what you are listening to.

What is this, and why is it important? 

Before obtaining an answer to this question, you need to understand certain things.

Audio Frequency Spectrum

Frequency response varies by the audio device being used, and people find this number expressed in Hertz (Hz).

When purchasing an audio device, look for this information on the package to learn more about the product and whether it meets your needs. 

When comparing audio devices, you’ll see this number expressed as a range. The bottom number provides information about the lowest frequency the device delivers and the higher number offers information about the highest frequency delivered by the device.

However, humans only hear certain frequencies known as audible or audio frequencies, and the range humans hear goes by the name audio spectrum. 

The pitch allows you to determine whether a sound is high or low, but humans need a clear and stable frequency to distinguish the pitch from other sounds.

The pitch is subjective because people hear sounds in different ways thanks to sound perception nuances. You may say a sound is high while the person sitting next to you says it is low.

It’s important to understand the difference between frequency and pitch.

Frequency remains objective while the pitch is subjective. 

Now let’s delve deeper to get a better understanding.

What is the Audio Frequency Spectrum? 

Audio frequency refers to an audio signal’s pitch and how low or high this pitch is. For example, the highest C on a grand piano vibrates at 4,186 times per second, and people refer to this frequency as 4.186 kiloHertz or 4.186kHz. The low C found on the same piano only vibrates 32.7 times per second, giving this a frequency of 32.7 Hertz or 32.7Hz. 

Certain sounds remain inaudible to humans but measuring them becomes possible when you count the number of repeated cycles of a wave within one second. What many people don’t know is changes in the temperature impact audio frequencies. They can differ in hot and cold environments. 

Low frequencies compromise the bass region of the audio frequency or sound frequency spectrum, and people often feel the lowest sounds rather than hearing them. In contrast, people describe high frequencies as piercing. What is surprising is many animals hear these sounds and they don’t appear to affect the animals the same way they do humans. 

Many individuals find they struggle to hear high frequencies as they get older. Humans hear frequencies from 20 Hertz to 20 kiloHertz but find their maximum audible frequency decreases as they age. This isn’t unexpected, but we can prevent some hearing loss. 

How is the Audio Frequency Spectrum Useful?

Distinct sounds have different amounts of energy and occupy different frequency ranges. People often estimate the main frequency of a sound, but find they might need to judge sounds individually.

For instance, a person recording a song needs this information to find the right balance between the unique sounds. The same holds true for production recordings. With this information, people find they can discuss music and sound, adjust the graphic equalizer on their audio device, gain a better understanding of what they hear, and protect their hearing. 

What are Sound Frequencies? 

Different frequencies at different decibel levels create sound, with each frequency measured separately. For instance, when a tree branch cracks and falls off a tree, it produces sound at all frequencies. However, the most prevalent sound becomes the crackling noise people associate with this action. As a result, the decibel level associated with the upper frequencies receives a boost. 

Humans hear sounds between 20Hz and 20,000kHz as mentioned above. Dogs, in contrast, hear sounds up to 44kHz while dolphins hear much higher sounds, those in the 150kHz range. 

A person’s ability to hear sounds coming from a speaker depends largely on their ears, along with the speaker’s operating performance. 

Tower speakers typically handle sounds in the 40Hz range, but bookshelves come with less low-end extension. They go up to 60 or 7-Hz. People often sing in the 80Hz range or higher, while their ability to localize the sound dissolves under 100Hz. Furthermore, developing lower frequencies takes longer. 

Sine waves are simple sounds, as they comprise a single tone at a particular frequency. On the other hand, white noise occurs when a person hears all single frequencies across the audio frequency spectrum simultaneously. Everyday sounds fall between these two extremes. 

What are the Audio Frequency Spectrum Ranges? 

Individuals divide the sound frequency spectrum into seven ranges or bands. Certain situations call for fewer bands or ranges, but people must know about the common ones they will come across. Men and women might find the frequency where the range ends or begins varies slightly, but these remain the most common. 

  • Sub-bass: 16-60Hz
  • Bass: 60-250Hz
  • Lower midrange: 250-500Hz
  • Midrange: 500-2kHz
  • Higher midrange: 2-4kHz
  • Presence: 4-6khz
  • Brilliance: 6-20kHz

However, many people prefer to use simplified terms when talking about spectrum ranges. If you want to do the same, the word bass covers the bass and sub-bass ranges; mids refers to the lower midrange, midrange, and higher midrange categories; and highs include the presence and brilliance ranges. Quite a few individuals use these subjective terms. All are appropriate, and you pick which term you use based on the context in which the subject is being discussed. 

Using a Frequency Response Chart

Devices respond to frequencies of sound differently, which experts refer to as frequency response. To measure this element, a person inputs tones of various frequencies into the device, making sure they input these tones at the same level. When this tone exits the device, the individual measures the level of the tone to determine if all tones leaving the device do so at the same level. Perfect devices emit all tones at the same level, but these devices don’t exist.

Excellent speakers take tones between 80Hz and 20kHz and put them out between 86 and 90dB. Average speakers put out these tones in the 83 to 93dB range. Inferior quality speakers provide tones in the 80 to 96dB range or worse. 

When all tones come out the same, people find they hear the sounds much as the person originating the sound intended. Frequency response errors may or may not matter. This depends on the magnitude, frequency, and bandwidth of the error, but keep this in mind if something doesn’t sound right when you are using a device. This may be where you need to look to identify the problem. 

Audio Frequency Range and Enclosure Design

You must understand the connection between the audio frequency range and enclosure design to get the most from your device. Smaller speakers move faster. As a result, they are better equipped to produce higher frequencies accurately, doing so without introducing undesirable harmonics. People often purchase smaller speakers to save money and space, only to discover they benefit in other ways. 

Objects naturally want to vibrate at a certain frequency, and we know this phenomenon as resonance. When this vibration occurs in an audio device, you will hear a buzzing noise or unwanted rattles. Keep this in mind when choosing a speaker or other audio enclosure, as you don’t want these sounds interfering with your listening experience. Choose an enclosure with a different resonant frequency than the expected audio output. This prevents unwanted harmonics. 

The materials used for the audio enclosure also play a role in the listening experience. When purchasing speakers, look for those with a light cone or diaphragm, as this allows it to respond rapidly while remaining rigid during movement. Look for common materials such as paper and mylar, ones that are light and stiff. In addition, choose a speaker that uses rubber to connect the diaphragm and frame for the optimal listening experience. 

Audio Frequencies and EQ

Equalizers aren’t as complicated as many believe. These devices contain ten or 12 volume controls, and each control addresses one specific area of the frequency spectrum. A bass or treble control boosts everything from the midrange up or down, affecting roughly 30 percent of the frequency spectrum when doing so. 

An equalizer allows the user to reproduce the entire frequency spectrum of the piece with no loss of accuracy. This helps to revive inadequate recordings or reproductions. In addition, individuals who struggle with hearing loss find the equalizer allows them to adjust certain aspects of the frequency spectrum so they can hear the piece as the creator intended once again. 

Music and the Frequency Spectrum

Did you know the Music Commission of the Italian government decided all orchestras and instruments needed to use a tuning fork that vibrates at 440Hz? They did so back in the late 1800s to ensure musical performances the world over would sound the same. The commission previously recommended tuning instruments to 435Hz, although France tuned instruments to 432Hz. 

The American Federation of Musicians followed suit in 1917, and an agreement was reached worldwide in 1953 to tune the middle “A” on the piano to exactly 440Hz. As a result of this agreement, men and women tune all musical instruments in the West to 440Hz, with other notes being tuned in standard mathematical ratios from the middle “A.” Thanks to the agreement, instruments the world over sound the same, so you can go from Canada to Australia and know the music won’t change when doing so. 

However, there remains some disagreement whether 440Hz is appropriate. Some individuals within the industry claim the correct Hz for middle “A” is 432 or 438 with one group claiming it should be 528Hz. However, the standard remains 440Hz. Only time will tell if it changes. 

Mixing Music with Spoken Voices

Individuals who love to experiment with new things enjoy having access to an equalizer on their audio devices. When this equalizer, you choose which bands of frequencies you want to boost and which you wish to cut. 

People often remove frequencies from one sound to allow the same frequencies to be better heard in another sound happening simultaneously. For instance, a person may talk with an instrument playing in the background. By removing those frequencies that appear in both sounds, you can ensure we clearly hear the person speaking. 

However, this serves as only one type of scenario where removing frequencies becomes of great help to the overall project. The technique used to remove these frequencies differs based on what is taking place in the project. For example, if you have a song playing in the background when a person speaks, the frequencies associated with the song’s vocals need alteration. Use a different technique, however, when an instrumental is playing in the background, as there aren’t vocals competing with the speaker. 

Frequently Asked Questions

  1. What is the sound frequency spectrum? The sound frequency spectrum refers to the range of frequencies humans can hear and interpret. The range runs from 20Hz to 20kHz, although a person finds they can’t hear as many frequencies as they get older.
  2. What is the audio frequency? The audio frequency is the number of waveforms created in one second.
  3. What frequency is most music? Musicians across the globe tune their instruments to 440Hz to ensure a piece sounds the same regardless of where the musician is playing.
  4. What is a good frequency response for speakers? Outstanding speakers have a frequency response that closely mimics the frequencies at which the artist originally recorded the piece. As mentioned above, excellent speakers take tones between 80Hz and 20kHz and put them out between 86 and 90dB.

This serves as an overview of the audio frequency spectrum. Delve more if you wish into one particular area that interests you or that you feel will provide you with the most benefit. This varies for each individual, as one person’s audio experience differs greatly from another person’s experience. The goal is to obtain the best experience for your specific needs. 

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