Noob question about speaker frequency reproduction accuracy

[fairy25]

Hi, I'm a new member here, and this is my first post. I have a pair of budget speakers (the Microlab B77BT) that I use for music listening. One time, I played sinewave frequencies on these speakers to try to EQ for my room modes and I noticed something like this. For some frequencies like 87 Hz and 88 Hz, the speakers just sound the same, I can hear no difference. If that's not my ears, it must be that the speakers are not producing the correct frequencies (or maybe the room acoustics).

My questions are: do speakers that have decent frequency response behave like that? does this affect the sound quality significantly? what measurements should I look at for this kind of inaccuracy?

Thanks a lot for reading my post and giving facts/opinions.

 

[tomtoo]

No its just not easy to hear a 1Hz difference.

 

[kemmler3D]

Hi, I'm a new member here, and this is my first post. I have a pair of budget speakers (the Microlab B77BT) that I use for music listening. One time, I played sinewave frequencies on these speakers to try to EQ for my room modes and I noticed something like this. For some frequencies like 87 Hz and 88 Hz, the speakers just sound the same, I can hear no difference. If that's not my ears, it must be that the speakers are not producing the correct frequencies (or maybe the room acoustics).

My questions are: do speakers that have decent frequency response behave like that? does this affect the sound quality significantly? what measurements should I look at for this kind of inaccuracy?

Thanks a lot for reading my post and giving facts/opinions.

It's hard to say exactly what you are hearing from this description.

As @tomtoo points out, yes it's hard to hear a 1hz difference when you are playing tones, regardless of the speaker.

That said, some lower-quality speakers do have a problem with "one-note bass" which is where the resonance from the port/cabinet is too strong and you hear that frequency more than you are supposed to. So if you're hearing 87hz even if you're playing 92hz, that might be the problem. Since the Microlab B77BT are a very inexpensive, small ported speaker, it's not unlikely that you would have that issue.

And welcome to ASR!

 

[fairy25]

No its just not easy to hear a 1Hz difference.

I'm sure I can hear 1Hz difference well for low frequencies below 90Hz with my headphones. The example I give in the post is just an example to describe a symptom. The inaccuracy can sometimes be that, for example, 88 Hz sounds lower than 87 Hz, or it can be 90Hz sounds the same as 88Hz, etc. My point is, the measurement devices can surely pick up those incorrect frequencies. But, I don't know what measurement results can show that kind of error. So I'm asking.

 

[tomtoo]

I'm sure I can hear 1Hz difference well for low frequencies below 90Hz with my headphones. The example I give in the post is just an example to describe a symptom. The inaccuracy can sometimes be that, for example, 88 Hz sounds lower than 87 Hz, or it can be 90Hz sounds the same as 88Hz, etc. My point is, the measurement devices can surely pick up those incorrect frequencies. But, I don't know what measurement results can show that kind of error. So I'm asking.

Ok lets make this clear. Your question is can a speaker play 88Hz louder than 87Hz? Get i this right?

 

[NTK]

I do not know of a physical mechanism that will cause a loudspeaker to reproduce sound at a slightly different frequency from the source frequency, at least for a single tone.

 

[fairy25]

Ok lets make this clear. Your question is can a speaker play 88Hz louder than 87Hz? Get i this right?

My question is, can a speaker play 88Hz when being fed with 87Hz or 86Hz audio signal? I believe an ideal speaker should produce exactly 88Hz if fed with 88Hz audio signal.

 

[tomtoo]

My question is, can a speaker play 88Hz when being fed with 87Hz or 86Hz audio signal? I believe an ideal speaker should produce exactly 88Hz if fed with 88Hz audio signal.

No it plays the frequence what it is feed with. It cant do something else.

 

[Sokel]

You can try playing 87Hz on one speaker and 88Hz on the other at the same time.
Then play the same to both.

If you don't hear a difference then you must have a problem.

 

[kemmler3D]

My question is, can a speaker play 88Hz when being fed with 87Hz or 86Hz audio signal? I believe an ideal speaker should produce exactly 88Hz if fed with 88Hz audio signal.

No it plays the frequence what it is feed with. It cant do something else.

I would say, depending on distortion and resonances, you certainly could be hearing an 88hz resonance excited if you're feeding 86 or 87hz to the speaker. The speaker cone itself will be moving exactly at 86 or 87hz. But what you actually hear will not be purely 86 or 87hz unless the speaker (including cabinet, port, etc) totally lacks distortion and resonances in that area. In a cheap speaker like the one we're talking about, I would not be surprised at all if you were hearing some gnarly resonances.

 

[tomtoo]

I would say, depending on distortion and resonances, you certainly could be hearing an 88hz resonance excited if you're feeding 86 or 87hz to the speaker. The speaker cone itself will be moving exactly at 86 or 87hz. But what you actually hear will not be purely 86 or 87hz unless the speaker totally lacks distortion and resonances in that area. In a cheap speaker like the one we're talking about, I would not be surprised at all if you were hearing some gnarly resonances.

If you realy had the bad luck that you have a strong 88Hz resonance. And you bring it to live with 87 Hz you could maybe hear a mix. But the driver itself can only do what it gets. So the driver plays 87Hz when it gets 87Hz.

 

[kemmler3D]

If you realy had the bad luck that you have a strong 88Hz resonance. And you bring it to live with 87 Hz you could maybe hear a mix. But the driver itself can only do what it gets. So the driver plays 87Hz when it gets 87Hz.

The speaker in question is small, ~30w, and has a 4" driver with a port, so I wouldn't be surprised if it was (poorly) tuned that high. To get a ~4" driver to go much lower, you need an expensive driver, DSP, lots of watts, or all 3.

It's also possible room modes are the problem here!

 

[tomtoo]

There are possible things that make to hear the difference even harder to hear than it already is. One Hz i can only hear on headphone in direct switch. I not say i have the best ears.

 

[danadam]

In the attachment there is a file with -3 dBFS stereo signal. For the first 5 seconds it is 88 Hz in both channels and in the next 5 seconds it is 88 Hz in the left channel and 87 Hz in the right channel. Then the pattern repeats twice more. If everything is ok with the speakers then you should hear continuous tone when the frequencies are the same and a beating (1 beat per second) when the frequencies are different.