Re: [AUDITORY] Tweeters for noise trauma ("Ravicz, Mike" )

Subject: Re: [AUDITORY] Tweeters for noise trauma From: "Ravicz, Mike" <Mike_Ravicz@xxxxxxxx> Date: Fri, 12 Feb 2021 15:01:57 +0000 --_000_CO6PR04MB757141179119EEDDB578EE6AB08B9CO6PR04MB7571namp_ MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable Hello Boris, I would add some to what Bob mentioned, but also ask some questions: In the studies you refer to, are the noise trauma stimuli delivered in the = free field or in a closed acoustic system attached to the ear? If in a clo= sed system, it is quite easy to develop 130 dB SPL. The reason has to do with the acoustic load (impedance) that the speaker se= es. As Bob mentions, most speakers are specified to deliver a certain soun= d pressure level at a certain distance from the speaker - because the sound= radiates into a 3-D space, the sound power per unit area decreases as the = square of the distance from the speaker, and therefore the sound pressure d= ecreases linearly with the distance from the speaker. (In a reverberant sp= ace, the echoes mean that there is more sound power, because it does not ra= diate away.). Speakers are specified in terms of sound pressure, because th= at=92s easy to measure. In fact, what limits them is the electric current= you can send to them without overheating, and the output related to the cu= rrent is the sound volume velocity. In a closed acoustic system, for a given electrical drive, the same volume = velocity will produce a higher sound pressure because the acoustic impedanc= e that the speaker sees is much higher. At our lab, we can generate 130 dB= SPL or so in a mouse ear from an old Radio Shack speaker (40-1310 or 40-13= 77) or a standard Beyer DT-48 audiometric earphone, because the sound is de= livered from the speaker directly to the ear through a tube fit closely to = the ear, and the small tube and ear have a much higher impedance than the o= pen field. These tweeters were marketed to the amateur audiophile and have= a frequency response far beyond the range of human hearing - but ideal for= small animals. The electrodynamic tweeters actually have a fairly flat fr= equency response; the piezoelectric tweeters, not so much. More recently we have used a Skanspeak (? I=92m not at my office and don=92= t have that info handy) or Fostex speaker (<https://www.madisoundspeakersto= re.com/bullet-tweeters/fostex-ft17h-horn-super-tweeter/> - looks like a cop= y of the old Radio Shack 40-1310) for midrange sounds and a small concave d= ome tweeter (originally through Parts Express, now available through Digi-K= ey, I believe) for higher-frequency sounds (~2-50 kHz). As Bob brings up, what is the frequency range you=92re interested in? As h= e also mentions, speakers are usually rated for =93music power=94, which as= sumes that the sound frequency and level vary with time. Using a steady-st= ate noise delivers much more actual power of the same combination of curren= t and voltage. To find your speaker=92s effective power handling capabilit= y, you may just need to play your stimulus for awhile and monitor the sound= output level and the temperature at the back of the speaker: If the former= goes down or the latter goes up, you=92ll need to turn down the voltage. A last thought: As you have probably discovered, few tweeters seem to stay = on the market for very long. Until a few years ago, one could still get so= me of these old tweeters on eBay, but they have been discovered - but there= =92s still this: <https://www.ebay.com/itm/Radio-Shack-40-1310B-Horn-Super-= Tweeter/174607236018?hash=3Ditem28a766fbb2:g:UDkAAOSwtrNgCzmP>. Best just = to spend a couple hundred dollars/euros and get half a dozen different mode= ls and try them out; and once you find one that will work, buy several spar= es. Hope this is helpful - Mike ________________________________ From: AUDITORY - Research in Auditory Perception <AUDITORY@xxxxxxxx>= on behalf of Henrik G. Sundt <hsundt@xxxxxxxx> Sent: Thursday, February 11, 2021 10:18 AM To: AUDITORY@xxxxxxxx <AUDITORY@xxxxxxxx> Subject: Re: Tweeters for noise trauma External Email - Use Caution How are the ethical concerns in animal testing at such sound pressure level= s considered? Henrik Sundt > 11. feb. 2021 kl. 11:12 skrev Boris Gour=E9vitch <boris@xxxxxxxx>: > > 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. Warre= n, Fenton et al, J Neuroscience 2020; Amanipour et al, 2018; Chen, Sheppar = and Salvi 2016; Novak, Zelenka et al, 2016) which actually used pretty comm= on tweeters to do that. Technical specifications for these tweeters do not = really indicate that they could handle such high SPL (and therefore such hi= gh voltage). How did they determine that ? How can we know then ? Only by s= ensitivity measure adjusted for the watt power of the speaker ? > > Let's take an example: in the Warren et al above cited, the Visaton speak= er from RadioSpare is used to deliver 3kHz at 126 dB SPL. The technical spe= cifications (https://docs.rs-online.com/170c/0900766b802e5b23.pdf) 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 the= ir speaker ? > > Same question with other speakers as well. I'm not an acoustician/electro= nician and I am probably missing something here. > > Many thanks for your help. Also, many of the tweeters from the papers abo= ve 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 Gour=E9vitch > 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: http://www.pi314.net/ > > > -- > L'absence de virus dans ce courrier =E9lectronique a =E9t=E9 v=E9rifi=E9e= par le logiciel antivirus Avast. > https://www.avast.com/antivirus The information in this e-mail is intended only for the person to whom it i= s addressed. If you believe this e-mail was sent to you in error and the e-= mail contains patient information, please contact the Mass General Brigham = Compliance HelpLine at http://www.massgeneralbrigham.org/complianceline . I= f the e-mail was sent to you in error but does not contain patient informat= ion, please contact the sender and properly dispose of the e-mail. --_000_CO6PR04MB757141179119EEDDB578EE6AB08B9CO6PR04MB7571namp_ MIME-Version: 1.0 Content-Type: text/html; charset="windows-1252" Content-Transfer-Encoding: quoted-printable <html> <head> <meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DWindows-1= 252"> <style type=3D"text/css" style=3D"display:none;"> P {margin-top:0;margin-bo= ttom:0;} </style> </head> <body dir=3D"ltr"> <div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size= : 12pt; color: rgb(0, 0, 0);"> Hello Boris, <b= r> I would add some t= o what Bob mentioned, but also ask some questions: In the studies you= refer to, are the noise trauma stimuli delivered in the free field or in a= closed acoustic system attached to the ear?  If in a closed system, it is quite easy to develop 130 dB SPL. <b= r> The reason has to = do with the acoustic load (impedance) that the speaker sees.  As Bob mentions, most speakers are specified to deliver a certain so= und pressure level at a certain distance from the speaker - because the sou= nd radiates into a 3-D space, the sound power per unit area decreases as th= e square of the distance from the speaker, and therefore the sound pressure decreases linearly with the dist= ance from the speaker.  (In a reverberant space, the echoes mean that there is more sound po= wer, because it does not radiate away.). Speakers are specified in terms of= sound pressure, because that=92s easy to measure.   In fact, what limits th= em is the electric current you can send to them without overheating, and th= e output related to the current is the sound volume velocity. <b= r> In a closed acoust= ic system, for a given electrical drive, the same volume velocity will prod= uce a higher sound pressure because the acoustic impedance that the speaker= sees is much higher.  At our lab, we can generate 130 dB SPL or so in a mouse ear from an = old Radio Shack speaker (40-1310 or 40-1377) or a standard Beyer DT-48 audi= ometric earphone, because the sound is delivered from the speaker directly = to the ear through a tube fit closely to the ear, and the small tube and ear have a much higher impedance than t= he open field.  These tweeters were marketed to the amateur audiophile and have a fr= equency response far beyond the range of human hearing - but ideal for smal= l animals.  The electrodynamic tweeters actually have a fairly flat frequency re= sponse; the piezoelectric tweeters, not so much. <b= r> More recently we h= ave used a Skanspeak (? I=92m not at my office and don=92t have that info h= andy) or Fostex speaker (<https://www.madisoundspeakerstore.com/bullet-t= weeters/fostex-ft17h-horn-super-tweeter/> - looks like a copy of the old Radio Shack 40-1310) for midrange sounds and = a small concave dome tweeter (originally through Parts Express, now availab= le through Digi-Key, I believe) for higher-frequency sounds (~2-50 kHz). <b= r> As Bob brings up, = what is the frequency range you=92re interested in?  As he also mentions, speakers are usually rated for =93music power= =94, which assumes that the sound frequency and level vary with time.  Using a steady-state noise delivers much more actual power of the sa= me combination of current and voltage.  To find your speaker=92s effective power handling capability, you ma= y just need to play your stimulus for awhile and monitor the sound output l= evel and the temperature at the back of the speaker: If the former goes dow= n or the latter goes up, you=92ll need to turn down the voltage. <b= r> A last thought: As= you have probably discovered, few tweeters seem to stay on the market for = very long.  Until a few years ago, one could still get some of these old tweeter= s on eBay, but they have been discovered - but there=92s still this: <ht= tps://www.ebay.com/itm/Radio-Shack-40-1310B-Horn-Super-Tweeter/174607236018= ?hash=3Ditem28a766fbb2:g:UDkAAOSwtrNgCzmP>.  Best just to spend a couple hundred dollars/euros and get half a doz= en different models and try them out; and once you find one that will work,= buy several spares.   <b= r> Hope this is helpf= ul - Mike <b= r> </div> <div id=3D"appendonsend"></div> <hr style=3D"display:inline-block;width:98%" tabindex=3D"-1"> <div id=3D"divRplyFwdMsg" dir=3D"ltr">From: AUDITORY - Research i= n Auditory Perception <AUDITORY@xxxxxxxx> on behalf of Henrik = G. Sundt <hsundt@xxxxxxxx> Sent: Thursday, February 11, 2021 10:18 AM To: AUDITORY@xxxxxxxx <AUDITORY@xxxxxxxx> Subject: Re: Tweeters for noise trauma <div> </div> </div> <div class=3D"BodyFragment"> <div class=3D"PlainText">        Externa= l Email - Use Caution        How are the ethical concerns in animal testing at such sound pressure level= s considered? Henrik Sundt > 11. feb. 2021 kl. 11:12 skrev Boris Gour=E9vitch <boris@xxxxxxxx&g= t;: > > 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. Wa= rren, Fenton et al, J Neuroscience 2020; Amanipour et al, 2018; Chen, Shepp= ar and Salvi 2016; Novak, Zelenka et al, 2016) which actually used pretty c= ommon tweeters to do that. Technical specifications for these tweeters do not really indicate that they could h= andle such high SPL (and therefore such high voltage). How did they determi= ne that ? How can we know then ? Only by sensitivity measure adjusted for t= he watt power of the speaker ? > > Let's take an example: in the Warren et al above cited, the Visaton sp= eaker from RadioSpare is used to deliver 3kHz at 126 dB SPL. The technical = specifications (<a href=3D"https://docs.rs-online.com/170c/0900766b802e5b23= .pdf">https://docs.rs-online.com/170c/0900766b802e5b23.pdf</a>) indicate 30W max and a sensitivity of 86 dB. Thus, it seems that this spea= ker could not deliver above 101 dB SPL. How did the authors do to avoid dam= aging their speaker ? > > Same question with other speakers as well. I'm not an acoustician/elec= tronician 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 safe= ly using at high SPLs, please do not hesitate to tell me. > > Best regards > > Boris > > -- > Dr Boris Gour=E9vitch > 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: <a href=3D"http://www.pi314.net/">http://www.pi314.= net/</a> > > > -- > L'absence de virus dans ce courrier =E9lectronique a =E9t=E9 v=E9rifi= =E9e par le logiciel antivirus Avast. > <a href=3D"https://www.avast.com/antivirus">https://www.avast.com/anti= virus</a> </div> </div> <div>The information in this e-mail is intended only for the person to whom= it is addressed. If you believe this e-mail was sent to you in error and t= he e-mail contains patient information, please contact the Mass General Bri= gham Compliance HelpLine at http://www.massgeneralbrigham.org/compliancelin= e . If the e-mail was sent to you in error but does not contain patient inf= ormation, please contact the sender and properly dispose of the e-mail.</di= v></body> </html> --_000_CO6PR04MB757141179119EEDDB578EE6AB08B9CO6PR04MB7571namp_--

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