| I’ll be honest that I haven’t read the full thread, but I’d you are truly interested in ultra-high frequencies there are a surprising number of ‘super tweeters’ that have greatly extended (and many with surprisingly flat) frequency response, that can reach 100kHz in several cases.
Just one example: https://www.madisoundspeakerstore.com/super-tweeters/lcy-100k-mk2-top-mount-supertweeter-each/Regards, Neil Waterman
Sent from my iPhone On Feb 14, 2021, at 00:10, Boris Gourévitch <boris@xxxxxxxxx> wrote:
Thank you everyone for your replies. A
short summary of some replies to the list or those I received in
private messages as well:
- distance really matters. From the
data at 1m away, you can easily add 6dB when halving the distance
and therefore 18dB at 12cm of the ear. I must admit I completely
forgot this point when I asked my question.
- a 3D cone or an insert will amplidy
again the signal energy to reach traumatizing levels but in that
case it is mostly valid for one animal or even one ear.
- common tweeters could do the job
thanks to these distance/cone tricks. Their quality/frequency
range does not always allow reaching very high frequencies
- sensitivity at 1m is crucial here and
depends on the quality of the manufacturer. If we start from 86 dB
at 1m, it is not the same than starting from 96 dB to use the
distance/cone tricks
- going upper than 20kHz (because of
mice) might be a problem for common tweeters and even compression
drivers. 30kHz could be possible (see smallest BMS drivers) but
I've seen no solution for 40kHz for instance. This is not common
for traumas though but this is to remember when using white noise
for instance.
- speakers specs have to be checked
when calibrating the speaker you bought, you can't only trust the
manufacturer and there is a variability from one speaker to
another as well (I observed that with the TDT EC1 speakers by the
way even if they're very good)
many thanks again, have a good week-end
Boris
Le 12/02/2021 à 16:25, Bernstein,Leslie
a écrit :
I'm copying here a response that Dr. Doug
Oliver sent to Boris and I'm attaching the documentation:
We have had great success
with Eminence tweeters when they are modified to prevent
overheating. A protocol is attached. We are using 116 dB at 11
cm from the front of the horn on awake mice. After
modification, our speakers have lasted over a year. At least
40 hours of use, one hour at a time.
Best of luck.
Les Bernstein
On 2/12/2021 12:10 AM, Bob Masta
wrote:
*** Attention: This is an external email. Use caution responding, opening attachments or clicking on links. ***
Speaker specs are always given at 1 meter distance. Animals being exposed are
usually much closer.
Note that this can cause its own problems if you are trying to expose multiple
animals using multiple close-by speakers, which will create interference
patterns. With noise stimuli, I have been able to reduce that problem somewhat
by using two unrelated noise sources to drive alternate tweeters in the array.
Another issue is that the animal will move around in its cage, and may thus
move out of the main beam of a close-by speaker if it has space to do so.
Since you mentioned mice, I expect you will be working above 20 kHz. Tweeter
frequency responses tend to be very ragged in this region, probably since they
are made for humans(!). Be sure to get curves for the models you are
interested in.
Also note that simple speaker power-handling specs can be misleading in a major
way, if they assume that the speaker is used to reproduce music, and they state
the power applied to a full-range system that uses that tweeter. Assuming a
pink-noise power distribution that falls at 3 dB/oct, with the woofer using the
most power, the tweeter gets very little.
You may have to contact the maker directly for relevant data. High-power
tweeters tend to be expensive ($40 US seems to be typical at
https://urldefense.com/v3/__http://www.parts-express.com__;!!N0rdg9Wr!7g1-G7NsB8QT8y74rn5s0MhRhUHyHf_6d1Eehj5K0JcYeq5z5_0abG2259kayIA9Cw$ these days). The last time I set up a system to do this
was 2007. I ordered one each of 2 prospective models and ran my own tests. I
think they are out of production now. The Pyramid TW47 was the one I chose.
It hit 121 dB SPL at 9 inches driven by 4 Vrms in 1/3rd octave around 10 kHz,
or 118 dB with a full octave at 16 kHz.
Hope this helps!
Bob Masta
-------------------------
On 11 Feb 2021 at 11:12, Boris Gourévitch wrote:
Dear auditory list,
I was looking for a speaker (probably a tweeter) that would reach 120 to
maybe 130 dB SPL in a high frequency range (for mice).
I am a bit puzzled with the many papers inducing noise trauma (i.e.
Warren, Fenton et al, J Neuroscience 2020; Amanipour et al, 2018; Chen,
Sheppar and Salvi 2016; Novak, Zelenka et al, 2016) which actually used
pretty common tweeters to do that. Technical specifications for these
tweeters do not really indicate that they could handle such high SPL
(and therefore such high voltage). How did they determine that ? How can
we know then ? Only by sensitivity measure adjusted for the watt power
of the speaker ?
Let's take an example: in the Warren et al above cited, the Visaton
speaker from RadioSpare is used to deliver 3kHz at 126 dB SPL. The
technical specifications
(https://urldefense.com/v3/__https://docs.rs-online.com/170c/0900766b802e5b23.pdf__;!!N0rdg9Wr!7g1-G7NsB8QT8y74rn5s0MhRhUHyHf_6d1Eehj5K0JcYeq5z5_0abG2259mXNym04A$ ) indicate 30W max
and a sensitivity of 86 dB. Thus, it seems that this speaker could not
deliver above 101 dB SPL. How did the authors do to avoid damaging their
speaker ?
Same question with other speakers as well. I'm not an
acoustician/electronician and I am probably missing something here.
Many thanks for your help. Also, many of the tweeters from the papers
above are discontinued so if you know a pretty robust one that you are
safely using at high SPLs, please do not hesitate to tell me.
Best regards
Boris
--
Dr Boris Gourévitch
CNRS Researcher
Institut de l'Audition
UMR1120 Inserm, Institut Pasteur
63 rue de Charenton
75012 Paris, France
Tel: (+33) 1 76 53 50 41
Personal Web page: https://urldefense.com/v3/__http://www.pi314.net/__;!!N0rdg9Wr!7g1-G7NsB8QT8y74rn5s0MhRhUHyHf_6d1Eehj5K0JcYeq5z5_0abG2259nZ4-XLPA$
--
L'absence de virus dans ce courrier électronique a été vérifiée par le
logiciel antivirus Avast. https://urldefense.com/v3/__https://www.avast.com/antivirus__;!!N0rdg9Wr!7g1-G7NsB8QT8y74rn5s0MhRhUHyHf_6d1Eehj5K0JcYeq5z5_0abG2259kfhXW54Q$
--
Leslie R. Bernstein, Ph.D.
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