• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Hearing damage potential from metal dome tweeters?

ElNino

Addicted to Fun and Learning
Joined
Sep 26, 2019
Messages
557
Likes
722
I'm curious if anyone is aware of any research on possible hearing damage caused by the resonant peak of some metal dome tweeters or metal cone fullranges?

This isn't going to be a concern with many of the better speakers we discuss here that keep the resonant peaks fairly well-controlled, but for consumer and automotive speakers there are still often ferocious resonant peaks at the end of the audible range.

For example, I was looking at the SB Acoustics 2.5" fullrange (SB65WBAC25-4) for a possible car audio application yesterday. This is not a low-quality driver by any means, but it has a +15dB resonant peak at 20kHz (compared to its SPL at 1kHz). So when used as intended (fullrange), even at a modest music listening level of 85dB, it's consistently generating 100dB of content at 20kHz.

Does anyone know of any research regarding whether that has the potential to cause hearing damage? Obviously off-axis it seems like it should be fine, but for desktop computer speakers or some car audio applications, those drivers might be aimed directly at one's ears.

I'm mostly concerned about the potential effect on kids, as I'm too old to directly hear that 20kHz peak any more. It worries me that I may think the SPL is fine, but may be exposing others to hazardous sound levels.
 

voodooless

Grand Contributor
Forum Donor
Joined
Jun 16, 2020
Messages
10,223
Likes
17,799
Location
Netherlands
So when used as intended (fullrange), even at a modest music listening level of 85dB, it's consistently generating 100dB of content at 20kHz.
When listening to music with an average of 85 dB, any 20 kHz sound will not be 85 dB. Rather is 40 to 60 dB down from there.
 

ryanosaur

Major Contributor
Joined
Mar 17, 2022
Messages
1,501
Likes
2,375
Location
Cali
Too much SPL over time will damage hearing. Period. The cause of the sound doesn’t matter.

Any well designed speaker will likely be using one of a few possible techniques to make any breakup modes or other resonances inaudible. Thus shouldn’t even be a concern.
 

fpitas

Master Contributor
Forum Donor
Joined
Jul 7, 2022
Messages
9,885
Likes
14,191
Location
Northern Virginia, USA
When listening to music with an average of 85 dB, any 20 kHz sound will not be 85 dB. Rather is 40 to 60 dB down from there.
Exactly. 85dB at 20kHz would drill a hole through your ear drums.
 

Inner Space

Major Contributor
Forum Donor
Joined
May 18, 2020
Messages
1,285
Likes
2,938
... I was looking at the SB Acoustics 2.5" fullrange ... it has a +15dB resonant peak at 20kHz (compared to its SPL at 1kHz). So when used as intended (fullrange), even at a modest music listening level of 85dB, it's consistently generating 100dB of content at 20kHz.
A test sweep of equal input power across the frequency spectrum might excite the resonance, but in practice no program material will have enough energy at 20kHz to cause a problem. Almost all commercial program is silent there. Nothing to worry about.
 
OP
E

ElNino

Addicted to Fun and Learning
Joined
Sep 26, 2019
Messages
557
Likes
722
When listening to music with an average of 85 dB, any 20 kHz sound will not be 85 dB. Rather is 40 to 60 dB down from there.
This is a good point, thanks.

With musical selections that skew towards white noise (e.g., Merzbow or anything heavily clipped), would there potentially be a concern?
 

AdamG

Proving your point makes it “Science”.
Moderator
Forum Donor
Joined
Jan 3, 2021
Messages
4,636
Likes
14,918
Location
Reality
This is a good point, thanks.

With musical selections that skew towards white noise (e.g., Merzbow or anything heavily clipped), would there potentially be a concern?
In general it’s not any specific frequency range that causes harm to our ears. It’s the overall max SPL at our ears over time that causes hearing loss and ringing. There are tones of graphs and tables about sound SPL exposure. Here is one example from OSHA.

1669823459774.png
 

NTK

Major Contributor
Forum Donor
Joined
Aug 11, 2019
Messages
2,656
Likes
5,819
Location
US East
OP
E

ElNino

Addicted to Fun and Learning
Joined
Sep 26, 2019
Messages
557
Likes
722

Hmast

Active Member
Joined
Sep 5, 2022
Messages
152
Likes
92
Location
Paris
I'm curious if anyone is aware of any research on possible hearing damage caused by the resonant peak of some metal dome tweeters or metal cone fullranges?

This isn't going to be a concern with many of the better speakers we discuss here that keep the resonant peaks fairly well-controlled, but for consumer and automotive speakers there are still often ferocious resonant peaks at the end of the audible range.

For example, I was looking at the SB Acoustics 2.5" fullrange (SB65WBAC25-4) for a possible car audio application yesterday. This is not a low-quality driver by any means, but it has a +15dB resonant peak at 20kHz (compared to its SPL at 1kHz). So when used as intended (fullrange), even at a modest music listening level of 85dB, it's consistently generating 100dB of content at 20kHz.

Does anyone know of any research regarding whether that has the potential to cause hearing damage? Obviously off-axis it seems like it should be fine, but for desktop computer speakers or some car audio applications, those drivers might be aimed directly at one's ears.

I'm mostly concerned about the potential effect on kids, as I'm too old to directly hear that 20kHz peak any more. It worries me that I may think the SPL is fine, but may be exposing others to hazardous sound levels.
Are all metal dome tweeters prone to that kind of resonance issue?
 

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,313
Location
UK
Exactly. 85dB at 20kHz would drill a hole through your ear drums.
There must be signal at 20kHz though and what material has that?
 

Digby

Major Contributor
Joined
Mar 12, 2021
Messages
1,632
Likes
1,555
wasn't FM carrier frequency 19khz, so I doubt music from the radio has much in the way of frequencies up there.

With musical selections that skew towards white noise (e.g., Merzbow or anything heavily clipped), would there potentially be a concern?
Yes, it would be a concern as to why you would listen to stuff like that while driving o_O One needs to pay attention to the road.
 

sarumbear

Master Contributor
Forum Donor
Joined
Aug 15, 2020
Messages
7,604
Likes
7,313
Location
UK
wasn't FM carrier frequency 19khz, so I doubt music from the radio has much in the way of frequencies up there.
Yes, hence the stereo FM bandwidth is limited to 15kHz.
 

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,891
Likes
35,912
Location
The Neitherlands
And the 19kHz should have been filtered out by a notch filter in the audio path for stereo tuners.
Not so with cheaper (portable radios) though.
 

mhardy6647

Grand Contributor
Joined
Dec 12, 2019
Messages
11,213
Likes
24,175
In the good ol' days, tape recorders used to have switchable "MPX filters" to avoid the generation of audible artifacts (birdies) produced by the bias oscillator beating against the pilot signal (and, presumably, maybe some of the higher frequency manifestations) of the compatible MPX stereo system. :)

Gratuitous analog aside: To me -- and not that anyone asked ;) -- the FM MPX system is elegance that we just don't see any more in terms of an engineering solution to a problem (mono-FM compatible FM stereo broadcasting, in this case).

1678722545532.png

1678722484750.png

 

fpitas

Master Contributor
Forum Donor
Joined
Jul 7, 2022
Messages
9,885
Likes
14,191
Location
Northern Virginia, USA
In the good ol' days, tape recorders used to have switchable "MPX filters" to avoid the generation of audible artifacts (birdies) produced by the bias oscillator beating against the pilot signal (and, presumably, maybe some of the higher frequency manifestations) of the compatible MPX stereo system. :)

Gratuitous analog aside: To me -- and not that anyone asked ;) -- the FM MPX system is elegance that we just don't see any more in terms of an engineering solution to a problem (mono-FM compatible FM stereo broadcasting, in this case).

View attachment 271396
View attachment 271395
The structure of modern digital broadcasting is good engineering, too.
 

kemmler3D

Major Contributor
Forum Donor
Joined
Aug 25, 2022
Messages
3,008
Likes
5,612
Location
San Francisco
it's consistently generating 100dB of content at 20kHz.
Same as several other comments - not with normal music, which has rather little energy at that frequency. It may happen from time to time but not a concern day-to-day.
 

fpitas

Master Contributor
Forum Donor
Joined
Jul 7, 2022
Messages
9,885
Likes
14,191
Location
Northern Virginia, USA
Why you think so? Or did i gentnt a joke?
The vast majority of the power in music is in the frequencies below about 500Hz.
 

tomtoo

Major Contributor
Joined
Nov 20, 2019
Messages
3,607
Likes
4,514
Location
Germany
The vast majority of the power in music is in the frequencies below about 500Hz.

Yes but i dont care a shiit about 85dB at 20khz i just dont hear it. Why this should pierce my ears?
 
Top Bottom