Help about basic info

[Icy687]

Just new to this audio tech stuff, I look at specifications of earphones on websites and the specifications they show is frequency response which is always like 20k Hz to 20k KHz, none of which made sense to me.

I already have 2 kinds of wireless earphones at home, one of which is 44100 Hz and other is 48000 Hz.
Question how do I know this other frequency thing before I buy one; on websites (like boAt), their specs don't mention this, just that frequency response time.

[GrandNebSmada]

The part about 20Hz to 20kHz is about its ability to reproduce all frequencies that the human ear can hear. 

 

A quick relevant lesson about how audio is stored in a digital format because its relevant and important to understand this:

Audio is stored in a similar fashion to video. The computer takes many snapshots of what is happening in the moment over time and stores that data, then when you want to listen back it just plays those data points back in the right order. There's lots of math and other things that are involved as to why the numbers are the way they are precisely but the short explanation is that in order to accurately do that for all the frequencies that humans can hear (20Hz to 20kHz), you need to sample the audio at at least twice the highest frequency, and 44.1kHz is slightly higher than twice 20kHz. Devices with a higher sampling frequency like the 48kHz means they can sample frequencies much higher than what humans can hear which has certain advantages in some situations but is most likely not relevant to your situation.

What all this means is that if you're just buying headphones there's really no reason to pay attention to that sampling frequency spec, they're just putting more numbers on the page to make them look more impressive to uneducated buyers. The thing that is relevant to you is the tonal characteristics of the headphones, which is represented by a frequency response graph that indicates how well the headphones can reproduce each frequency between and including 20Hz to 20kHz.

[GrandNebSmada]

Relevant videos
 

 

8 minutes ago, GrandNebSmada said:

The part about 20Hz to 20kHz is about its ability to reproduce all frequencies that the human ear can hear. 

 

A quick relevant lesson about how audio is stored in a digital format because its relevant and important to understand this:

Audio is stored in a similar fashion to video. The computer takes many snapshots of what is happening in the moment over time and stores that data, then when you want to listen back it just plays those data points back in the right order. There's lots of math and other things that are involved as to why the numbers are the way they are precisely but the short explanation is that in order to accurately do that for all the frequencies that humans can hear (20Hz to 20kHz), you need to sample the audio at at least twice the highest frequency, and 44.1kHz is slightly higher than twice 20kHz. Devices with a higher sampling frequency like the 48kHz means they can sample frequencies much higher than what humans can hear which has certain advantages in some situations but is most likely not relevant to your situation.

What all this means is that if you're just buying headphones there's really no reason to pay attention to that sampling frequency spec, they're just putting more numbers on the page to make them look more impressive to uneducated buyers. The thing that is relevant to you is the tonal characteristics of the headphones, which is represented by a frequency response graph that indicates how well the headphones can reproduce each frequency between and including 20Hz to 20kHz.

 

[rippy4500]

20hz to 20khz is just the range of frequencies that the speakers can play, our ears cant hear outside of 20hz-20khz under normal conditions so you shouldnt worry about that.

 

And for sampling rate 44.1khz is fine since it can perfectly represent 22.05khz which is above what we can hear, 48khz sampling rate would be able to create 24khz.

[Spuriae]

For what it's worth, the frequency range spec (e.g. 20Hz - 20kHz) typically listed for headphones is completely meaningless because they don't list the test conditions.

The higher number (44.1kHz or larger) refers to the sample rate for the digital signal, and should never functionally be relevant in the headphone context for most people.

[mariushm]

If you're young and have recently cleaned your ears (ex went to the doctor to remove wax) you may hear up to 18-19 kHz 

Once you're in the 40-50s you'll probably be lucky to hear above 16.5 kHz

 

As for bass, you typically can notice stuff down to around 10-15 Hz, but you will "feel" with your body vibrations below that, if you listen to speakers. 

Some sound cards will have low pass filters that basically reduce anything below some threshold (ex maybe 6-8 Hz) a bit, because that can often be buzzing or noised caused by the electricity quality, not from the actual sound.

 

This anatomy fact, that human ears have problems hearing frequencies above some frequencies, is one of the things that  lossy audio encoders like MP3, Opus, AAC take advantage of, to reduce the size of audio files by throwing out or "simplifying" frequencies that may be harder to hear by human ears. 

You can see in the video below how at particular quality levels (configured by forcing the bitrate to 320kbps or 192 kbps), that the MP3 encoder chooses to cut out some amount of high frequency sounds .. at 320 kbps anything above 20kHz is cut, at 192 kbps the cut point is at around 18kHz and selectively cut out stuff between 16.5 and 18kHz where it determines it may be less noticeable, and at 128 kbps anything above around 16.5 kHz is cut.

 

 

 

 

 

20 HZ to 20kHz  means nothing really, if some headphones say that, they're probably lying... also it would be important to have some sort of graph showing how much the speakers deviate from accurate reproduction of the audio, if some frequencies are amplified or lowered (or accented)

Here's for example a review on rtings.com for some decent headphones:  https://www.rtings.com/headphones/reviews/sennheiser/hd-650#test_321

You can see the graphs which should these particular headphones reduce the bass a bit, while for the rest they're fairly accurate.

You can also see frequency response here : https://www.rtings.com/headphones/reviews/sennheiser/hd-650#test_1342

 

 

In order to reproduce a particular frequency accurately, there needs to be at least twice the amount of audio samples being reproduced by the sound card. That's the 44100 Hz  or 48000 Hz  - this means that the sound card would be able to reproduce frequencies up to 22050 Hz  or 24000 Hz  - 44100 Hz comes from Audio CDs  and 48000 Hz comes from DVDs and Blurays.

So you can set the frequency in Windows at 44100 or 48000, ideally you set to the frequency of majority of your files. If you are mainly listening to audio grabbed from Audio CDs which were mastered at 44100 Hz, then it would make sense to set in Windows the sound card to work with 44100, because otherwise you'd just waste CPU cycles converting 44100 to 48000.