Talk:Speed of sound

message: The proper term is "speed of sound", not "velocity of sound." Velocity refers to a vector, but sound is characterized by a scalar: the speed of sound waves in a material, independent of direction. In some materials, sound travels faster in some directions than others, but even in such circumstances it is not characterized (AFAIK) by a vector. -- CYD
:This may be correct (as far as velcoity is a vector and speed is a scalar), but is a bit of hair splitting. In Morse's "Theoretical" Acoustics, the index entries for "sound speed" and "sound velocity" are identical. A Scirus search reveals approximately the same number of "sound speed" annd "sound velocity" hits. "Sound velocity" abounds in geophysical literature. So both in technical and other literature velocity is not strictly used for the vectorial quantity. --AMR 22:16, 2004 Nov 5 (UTC)
:: Please consider that not every book is a bible (even a good one). The term "velocity of sound" is confusing for those who come here to learn and should not not be used. ---TRL 23:25, 2005 Nov 30
::: The term referring to a vector should not be used when speaking about waves as this phenomenon in general cannot be characterised by the velocity vector. In case of anisothropic materials (materials in which speed of sound does depend on direction) 2nd rank tensor (which may be represented by a square matrix) is used to describe material properties. --Mak Sym 213.134.172.253 18:19, 19 May 2007 (UTC)
thread_title:  Terminology 

message: Might be stupid, but I was wondering whether the speed of sound actually is the maximum speed that "pressure" can travel through matter. If that is true, we should include it in this article...
Pressure is considered a state variable, so talking about the "speed of movement of pressure" doesn't mean a whole lot.  Pressure doesn't "move" from one point to another.
As an explanation to a layman who may not know what a state variable is, one could accurately say the following: if you had a room with totally uniform pressure and then paused time, and you magically increased the pressure at one point in the room and then started time again, that pressure would "travel" at the speed of sound. To be more accurate, one would say that a wave of pressure would travel at the speed of sound.
::Far away from the source, if it's a low pressure, yes. The problem is that high pressure waves, such as the hypershock after a bomb detonation, often travel supersonically (like Mach 1.5 at least) for awhile before slowing down to sound velocity. So pure pressure waves can travel supersonically for a time, though there's always a drag and decelleration on them. This shouldn't surprise you: a shock of molecules moving faster than sound isn't going to slow down to sound speed after just ONE hit on the next layer of molecules. Speed of sound formulas assume gentle adiabadic compressions where the molecules only giggle back and forth a bit, and aren't been driving in any particular direction at great speeds above their normal one.SBHarris 18:11, 11 July 2006 (UTC)
replies: text: Shock waves are pressure waves that move faster than the speed of sound. Jalexbnbl 22:08, 30 August 2007 (UTC)
thread_title: Speed of sound = speed of movement of 'pressure'?

message: When are relativistic effects important???
Should that part be removed?
-----
Cosmologists now consider sound waves important in their description of the Big Bang.  They have discovered that the equations governing sound are actually very useful to them in explaining the small variations they've observed in the 2 deg Kelvin cosmic microwave background.
They think that since the primordial universe was a liquid-like blob at extreme temperature and pressure shortly after the Big Bang, sound waves would have been able to (and did) propogate within it.  The early universe supposedly also inflated faster than the speed of light.  So relativistic effects would certainly be important in any detailed consideration of the baby universe.  It's not trivial issue, either; those very minor differences in the pressures here and there in that early fireball created the universe we see today.
Other than that...I would think that any theoretical physicist who'd done enough serious drugs in high school that he decided to work out how fast a 'knock knock' joke would move inside a spinning neutron star (whose surface can be racing along at about 1/7th of the speed of light) would definitely need to take relativity into account. 66.11.164.72 03:48, 10 March 2006 (UTC)
replies: text: (Better late than never) Relativistc affects apprear close to the speed of light in vacuum, c. This is extremly higher. All light travel (in vacuum) with the same speed - for any beholder, this isn't the case with sound. Boeing720 (talk) 00:16, 13 December 2014 (UTC)
thread_title:  Relativistic effects 

message: Shouldn't that be a rise in pressure that causes condensation? Or alternatively, a drop in pressure accompangnied by an even larger drop in temperature as a result of adiabatic cooling?
:The condensation is caused by a rise in the relative humidity, which is caused by a drop in temperature, which in turn is a result of the drop in pressure.  It's the same reason clouds form when air rises.  Spiel496 (talk) 17:47, 23 December 2008 (UTC)
replies: text: I have changed the caption slightly to explain it happens at transonic speeds (sub-thru-super). Incidentally, info identifying the image says the Hornet was breaking the sound barrier off Pusan "over the Pacific Ocean". More likely over the Korea Strait in the Sea of Japan. ):.  Kaiwhakahaere (talk) 21:53, 26 September 2009 (UTC)
replies: text:  And just incidentally, you can tell in projectiles from the angle of the attached shock wave (which is very close to to a flat pancake 90 degrees here for the Mach angle), what the Mach number is. In the ideal weak-shock case, the Mach angle of the shock is given at arcsin(1/M) where M is the mach number. Here we have sin (~90 degrees)= ~ Mach number 1, by inspection. Higher speeds make the weak shock angle begin to bend toward being acute (Mach angles less than 90 degrees). SBHarris 06:59, 27 September 2009 (UTC)
thread_title:  Picture of Fighter Jet Breaking the Sound Barrier 

message: Should we add a section on the classic methods for the measurement of the speed of sound (for instance Kundt's tube) ? Cadmium 14:14, 1 January 2006 (UTC)
replies: text: In an overview style which doesn't get too practical, what could be a reason not to? Femto 15:18, 1 January 2006 (UTC)
thread_title: Experiments to measure the speed of sound

message: If you divide the universal gas constant by the molar mass of a specific gas, you cannot possibly end up with the universal gas constant again. Many people call that a "specific gas constant", some may have other names, but "universal gas constant" is positively wrong. Unfortunately, the current gas constant article adds to the confusion, I'll take the issue there as well. Algae 20:14, 1 January 2006 (UTC)
thread_title: Universal gas constant

message: According to p351 of Wood 1946 (who quotes from early work by Herzfeld and Rice) "... the adiabatic state is best guaranteed for the low frequencies, while for the higher frequencies the influence of heat conduction is larger ...".  Unless this statement is challenged by more recent research I suggest the paragraph about frequency dependence be either deleted or reversed.  
REF: A B Wood, A Textbook of Sound (Bell, London, 1946)
Thunderbird2 21:50, 8 July 2007 (UTC)
thread_title:  effect of frequency 

message: The speed of sound varies with the medium employed, as well as with the properties of the medium, especially temperature. The term is commonly used to refer specifically to the speed of sound in air. At sea level, at a temperature of 21 °C (70 °F) and under normal atmospheric conditions, the speed of sound is 344 m/s.
It makes no sense to give the speed of sound adding the words at the "standard atmosphere at sea level". We have the formula:   
:   
c = \sqrt{\gamma \cdot {p \over \rho}} \,   
   
   
Statement: The air pressure p and the density ρ of air are proportional at the same temperature. That means, the fraction p / ρ is always constant, even at "sea level". Cross always the useless words "At sea level".
If the temperature is the same, we get the the same speed of sound down at sea level and high on a mountain. 
John 21:50, 5 September 2007 (UTC)
thread_title:  Standard atmosphere at sea level 

message: Can the speed of sound rise in above its original speed in air (or any substances for that matter)LearnguyLearnguy (talk) 17:09, 27 April 2008 (UTC)
replies: text: After an explosion which expands faster than the speed of sound, there is a continuing disturbance called a hypershock which moves outward, faster than sound. Whether you consider it sound or not, is semantics. It's a bulk movement of a mass of air, which moves in a wave. It quickly slows to sonic velocity, and then propagates at that rate with less loss of energy over distance. SBHarris 08:29, 29 October 2008 (UTC)
thread_title:  Speed of sound 

message: The opening paragraph says "...343 m/s. This also equates to 1235 km/h, 767 mph, 1129 ft/s" By my calculation, 343 m/s = 1125.328048 ft/s which is easily enough rounded down to 1125 ft/s. The mistake is probably the result of someone changing the reference to 343 m/s from a previous notation of 344 m/s. I will correct the f/s calculation. MRJayMach (talk) 14:08, 16 September 2008 (UTC)
replies: text: I suggest that  the numbers in the first paragraph be reviewed. I corrected someone's vandalism but the numbers still don't look right. Rosattin (talk) 07:57, 26 December 2008 (UTC)
thread_title:  Math error in the first paragraph 

message: The “Basic Concept” section gives the following example:
All other things being equal, sound will travel more slowly in denser materials, and faster in stiffer ones. For instance, sound will travel faster in iron than uranium, and faster in hydrogen than nitrogen, due to the lower density of the first material of each set.
I'm pretty sure uranium is stiffer than iron, so the “all else equal” premise is not satisfied. The solids example might be replaced, for instance, with iron and carbon steel: the density should be similar, but the stiffness can vary widely.
*A good point, and we need to find two metals which are better matched, either for one property or the other. As you can see, somebody was trying for a match with stiffness with metals of very different density. I don't know what the stiffnesses are for very pure iron and uranium, though I know that very pure iron is quite soft-- reputably bendable by hand. In any case, agree that another example is needed.SBHarris 01:23, 12 January 2010 (UTC)
thread_title:  “Basic Concept” U/Fe example 

message: I created a table in OpenOffice Calc with temperatures per degree from -30˚C +35˚C, using the formula 331.3 + 0.606 * C, and the numbers vary with the ones listed in the table at Speed_of_sound#Tables. They match at 0˚C and 5˚C, but already at -5˚C and at +10˚C, they vary. My numbers are available here. Should the wikipedia table be updated, or are my numbers wrong? Rkarlsba (talk) 11:42, 3 September 2010 (UTC)
replies: text: The formula is an approximation. The table values are (I think) more accurate.  Spiel496 (talk) 13:51, 3 September 2010 (UTC)
thread_title:  Incorrect values in table? 

message: I'm pretty sure that somewhere there's a bit about China Airlines Flight 006 "almost certainly" breaking the sound barrier, but I can't seem to find it.  Can anyone help me out here?  —Preceding unsigned comment added by 66.189.116.112 (talk) 23:42, 28 September 2010 (UTC)
thread_title:  China Airlines 006 

message: The introduction states that the speed of sound in iron is 5,120 m/s, and then in the next paragraph states that the speed of sound in solids depends on whether the wave is transverse or longitudinal. So when the "speed of sound" is stated for a solid material such as iron, as it was above, is there a convention as to which speed is the one being referred to? I would assume it's the longitudinal case, because the paragraph is comparing it with the speed in various fluids, which carry longitudinal waves only.
--JB Gnome (talk) 22:54, 7 December 2010 (UTC)
replies: text: That's a very good question. In this case we know it's the longitudinal wave, because shear waves in iron only travel about 3000 m/sec. However, you never know what kind of wave speed you have until you know the system. Sometimes these things are given as speeds in "long thin rods," which you would THINK would have the same longitudinal-compression velocity as an infinite 3-D solid, except it doesn't. I can't think of an intuitive reason why not, but the speeds are not the same. Also, long thin rods have additional modes of shear stress waves that one doesn't find at all in a 3-D solid. These include torsion waves, and a kind of bending wave like a wave of vibration on a metal wire, neither of which even happen in 3-D solids. SBHarris 02:10, 8 December 2010 (UTC)
replies: text: In thin rods, the rod expands and contracts radially as the sound wave passes (assuming Poisson's ratio is nonzero).  In an infinite solid, it is constrained from doing so.  Thus the speed difference.  Anyway, yes, "speed of sound" without qualifiers usually means speed of pressure waves, rather than speed of shear waves, although that's not a real convention, nor should it be. Norman Yarvin (talk) 17:32, 8 December 2010 (UTC)
replies: text: Ah, thanks Norman. The things you learn while writing. Looking into this, I see that for thin rods the Young's modulus Y simply replaces the bulk modulus B in the equation, and that Y = 3B(1-2v) where v is Poisson's ratio. Figuring this at 0.3 (reasonable for metals like steel) that gives you Y = 3B(1-.6) = 1.2 B. Which means that sound travels FASTER in the thin rod by a factor of SQRT(1.2) =1.095. The ratio of rod/bulk speeds depends on Poisson's ratio: if it's larger than 0.33, a quite reasonable value, then it's easy to see that sound travels slower in thin rods than bulk, if it's less than 0.33, it goes faster in thin rods than bulk. Real values can be on either side of this value with non-zero and non-negative Poisson ratios (which must be from -1 to +1/2). So, again it's not that intuitive. If energy went into thin rod radial expansions and contractions I would presume that mostly sound would travel slower in thin rods, due to having this extra "way" to store compression-energy. SBHarris 23:12, 8 December 2010 (UTC)
thread_title:  Ambiguous introduction 

message: \frac{c_{\mathrm{rod}}}{c_{\mathrm{bulk}}} = \frac{\sqrt {\frac{Y}{\rho}}}{\sqrt {\frac{Y (1-\nu)}{\rho (1+\nu)(1 - 2 \nu)}}} = \sqrt {\frac {(1+\nu)(1 - 2 \nu)}{(1-\nu)}}  
The two speeds are equal only when Poisson's ratio is equal to zero. This is possible, as Poisson's ratio can take on values from -1 to +1/2 for materials. In a metal, where Poisson's ratio might typically be +1/3, the ratio of the speeds would be 2/3, meaning that the speed of sound is 50% faster in the bulk material than in the long, thin rod. I think this is right, but need to check before putting it in. Are there separate compression and sheer waves in a thin rod, or just one type of tangent-sheer wave? SBHarris 19:32, 28 July 2011 (UTC)
thread_title:  Thin rods 

message: Does the plot in the Practical Formula section add value to the article? The green trace is an "Approximation of the speed of sound in dry air based on the heat capacity ratio" and the red trace is the Taylor series approximation.  While it would be interesting to compare an approximation to the actual speed of sound, I don't feel it benefits the article to compare two approximations.  All we're doing is showing that sqrt(1+x) ≈ 1+x/2, which not specific to the phenomenon of sound.  Furthermore, the plot may mislead the reader that the green trace is accurate, even near absolute zero, where it's probably not.  Spiel496 (talk) 21:42, 19 September 2011 (UTC)
replies: text: No one came to its defense, so I removed it.  Spiel496 (talk) 19:05, 17 November 2011 (UTC)
replies: text:  Sorry, but I didn't notice your note. I've reverted removal of the graph, only for WP:BRD reasons-- I don't mean to be snarky. My defense argument is that it's not obvious from looking at THIS Taylor expansion that it gives the same results as the square root form, for -100 to +100 C, but diverges badly at colder and higher temps. Sure that's all in the equation, but you can't look at just the equation and realize that without the graph, unless you're a quantitative genius. The goodness of the Taylor expansion itself depends on the value of "x," the temp, with regard to the coefficients, so we're comparing y= A sqrt (1 + bx) to y = A (1 + bx/2), and x can be positive or negative, so it's not all that obvious what values of -x to +x are going to give y to within some fraction of a percent, in the expansion. Can YOU see the -100 to +100 C "good" range? I certainly agree that a plot of real values would help, but just knowing the valid range of the Taylor expansion with regard to the best analytic form (the square root equation) is helpful.  SBHarris 19:27, 17 November 2011 (UTC)

text: Good point, and no "snark" taken.  Still, I think it would be an improvement to limit the temperatures to a range where we know the square root function is valid.  Can we at least keep it above 100 Kelvin?  Liquid nitrogen doesn't behave as an ideal gas. Spiel496 (talk) 19:52, 17 November 2011 (UTC)
replies: text: Helium still does, though. I'll see if I can stick in some kind of qualification. The problem is that all these things depends on the reduced properties of gases (reduced pressures, reduced temperatures, etc), where these things are expressed in terms of the critical temps and pressures for the particular gas in question. For the validity of the square-root equation at the hot end, it depends on gamma staying constant, which in turn depends on on it being monatomic. For diatomics, to use gamma=7/5 it must be cold enough for the OTHER type of reduced temperature (T/theta, where theta is the Einstein temp) to be small. Otherwise gamma creaps up toward 9/7...   SBHarris 20:24, 17 November 2011 (UTC)
thread_title:  Plot in "Practical Formula" section 

message: How about a table of speed of sound in various mediums? Some of them are mentioned in the article, though. 85.217.39.114 (talk) 14:06, 30 July 2012 (UTC)
replies: text: The problem with such a table is that there are millions of kinds of "stuff." How do you limit it? You'd have to be very careful about having a few types of metals, a few types of crystals, a few types of liquids, and a few types of gases, all chosen carefully to illustrate the very ends of the ranges (gasses, for example, from hydrogen to UF6; metals from beryllium to lead)SBHarris 18:28, 30 July 2012 (UTC)
replies: text: How about a list with every matter of any kind? :D 85.217.46.150 (talk) 01:17, 10 August 2012 (UTC)
replies: text:  Sounds like a great idea for a list article per WP:LIST. Get to work! In the old days (when people were manic-crazy here) there was actually an article called List of Chinese people. Now, that's ambition. But there's still a List of Hong Kong people and a List of Chinese Americans, see  So I'm not making this up! SBHarris 05:33, 10 August 2012 (UTC)
thread_title:  speed in various stuff 

message: Shouldn't the intro sentence stating the speed of sound in dry air at a given temperature also specify the altitude (or, more specifically, air pressure) ?  The speed of sound in a gaseous medium does change with pressure, right?  I'm no physicist so I thought I'd post this here rather than make the edit myself.  I'm assuming the speed given is at sea-level, but I'm not sure.
Thanks!
Spiral5800 (talk) 00:59, 27 September 2012 (UTC)
replies: text: Sigh. Read farther and learn, dude! The speed of sound in an ideal gas is actually dependent on temperature only, and is NOT dependent on pressure. This is noted right in the lead of this article, and in explained in detail farther down. Don't you suppose it might be a good idea for you to read PAST the first sentence, before suggesting a change?  SBHarris 01:15, 27 September 2012 (UTC)
thread_title:  Intro sentence 

message: The article currently gives the speed of sound in dry air, at standard temperature, as 343.2 m/s. This is both wrong and misleading in the precision claimed. This value appears to have been cooked up as follows. Take the adiabatic index to be 1.400, T=293.15 K, and the molecular weight of air to be 28.9644 g/mol (the value from the US Standard Atmosphere). Plugging in numbers gives 343.24 m/s. This is wrong because air contains traces of gases that are not diatomic, so the adiabatic index isn't exactly 1.4. The article itself cites measured values ranging from 1.3991 to 1.403, with the middle of the range being a little higher than the diatomic value, presumably because of the presence of monoatomic gases such as argon, and despite the presence of polyatomic gases such as methane. Taking the middle of the range for the adiabatic index gives 343.36 m/s, the low end of the range gives 343.11 m/s, and the high end of the range gives 343.60 m/s. It clearly doesn't make sense to take a molecular weight from the USSA, but use an adiabatic index that isn't consistent with the mixture of gases defined in the USSA. What this really demonstrates is simply that it's silly to try to give the speed of sound in dry air at standard temperature to a precision of a tenth of a meter per second. The experimental range of variation of the adiabatic index is enough to make this precision meaningless. This is presumably why one sees a variety of values floating around on the internet. My students seem to be finding 343.2 m/s (presumably from WP) and also 343.6 m/s. My students' naivete about significant figures isn't by itself a reason to delete this sig fig from the article, but the considerations above show that the digit is not in fact significant given the experimental state of the art, and in any case has been derived from an inconsistent set of assumptions. (Much bigger changes would also result from temperature changes of a fraction of a degree, or a tiny bit of humidity.) For these reasons, I'm going to delete the final sig fig from the article.--207.233.84.11 (talk) 19:26, 20 February 2014 (UTC)
replies: text: Some presumably well-meaning person reinserted the bogus significant figure, and even added another bogus one, giving the speed of sound to 5 sig figs. This is wrong, for the reasons given above. I've re-deleted the false precision.--207.233.86.179 (talk) 23:48, 14 February 2017 (UTC)

text: Same thing again. Corrected again.--76.169.116.244 (talk) 03:14, 10 September 2018 (UTC)

text: "Standard temperature"? What is that? The speed-of-sound varies at different temperatures. 0˚C (32˚F) should be the agreed upon international condition for measuring the SOS. Therefore, making 742.1 mph the standard measurement for the SOS. 2601:589:4800:9090:D49F:F751:8A92:A7DE (talk) 12:27, 8 December 2020 (UTC)
thread_title: error and misleading precision in value given for speed of sound in air

message: Any value in adding a comment to the equations section that the letter "c" in the equations is based on the word "celerity"?  (As opposed to using "v" for velocity).  99.245.230.105 (talk) 09:37, 8 March 2014 (UTC)
thread_title:  c for celerity 

message: Someone should remake the equation images to remove the trailing "," (comma) and "." (period). I see they are also in the alt text expression. Those punctuation marks don't belong in the equations. It looks particularly bad for 273.15 - one occurrence has a "." above it and the other has it after the 5, i.e. "273.15."  If you want to add punctuation to the article, e.g. commas between several items (equations?), then do it in the HTML markup, not in the equation images. In fact, I would not even put those commas and periods in the article, i.e. when listing several equations or including an equation in the narrative.
For example: https://upload.wikimedia.org/math/9/3/f/93fe3a13923fef7a15be23e5c7fb6fed.png  — Preceding unsigned comment added by 69.196.151.159 (talk) 17:26, 21 June 2015 (UTC)
replies: text: Equations in a sentence should be punctuated. LaTeX equtions should have punctuation within the <math> tags (which puts them in the equation image) or else weird formatting thing can happen. See MOS:MATH#PUNC. Mysticdan (talk) 21:42, 12 August 2015 (UTC)
thread_title:  remove commas and periods from equation images 

message: "In gases, adiabatic compressibility is directly related to pressure through the heat capacity ratio (adiabatic index), and pressure and density are inversely related at a given temperature and composition, thus making only the latter independent properties (temperature, molecular composition, and heat capacity ratio) important."
This sentence is confusing me, surely the heat capacity ratio is set by the molecular composition?  For example (temperature and heat capacity ratio) would be ok, or (temperature and molecular composition) would be ok too, but having all three in there is seems wrong.  Also, what's meant by "latter independent properties"?  What makes them latter?  Not edited myself because I'm not completely sure about it all.
:I've tried to clarify. It's hard to say just what "molecular composition" means. For a pure gas with complex molecules at high temperatures (where vibration counts) what we want is the molecular formula, and indeed must have the structural formula, since n-pentane and tert-pentane have the same molecular formulas, but different structural formulas, and will different vibrational modes and thus heat capacities, and thus speeds of sound. You can in theory determine a gas heat capacity (and thus gamma) from just structural formulas (to give bending modes) and temperature, but it's a nasty problem in the heat capacity of gasses. Thus we cannot really say that temperature and molecular weight are the independent variables. That is true for monatomic gases, but for gases with complex molecules, the complexity must be taken account of, and simple molecular weight isn't enough to do it. Heat capacity (gamma) must either be given in addition to molecular weight for complex gas molecules, or else laboriously calculated ab initio from temperature and quantum mechanics. SBHarris 02:42, 30 August 2016 (UTC)
thread_title:  Heat capacity ratio 

message: According to the Method of style of Wikipedia this article should be stating values using the metric units first.
 
Unit choice and order  — Preceding unsigned comment added by 99.241.73.202 (talk) 22:54, 12 March 2016 (UTC)
replies: text: Thank you for pointing this out - the order was changed only very recently. It seems clear that SI unit should have the priority on a global topic like this, and I have changed it back. (Manual of style, not "method" of style): Noyster  (talk),  00:50, 13 March 2016 (UTC)
thread_title:  Why does the beginning of this article state speeds and such using the Imperial system and then the SI units? 

message: Hello fellow Wikipedians,
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*Added archive http://web.archive.org/web/20060429062028/http://www.bustertests.co.uk:80/answer/how-to-measure-the-speed-of-sound-in-a-laboratory/ to http://www.bustertests.co.uk/answer/how-to-measure-the-speed-of-sound-in-a-laboratory/
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thread_title:  External links modified 

message: Perhaps there is good reason for it, but the 2nd and 3rd equations in section "Practical formula for dry air" place the m/s units in the middle of the right-hand-side of the equation which just looks weird to me.  Aren't units conventionally placed at the end of an expression?  It also almost looks like the radical is under the slant division line which I don't think is the intent.  I think the m/s should be moved to the end of both of these equations.
: You are right. It's been fixed now. SBHarris 00:10, 17 August 2016 (UTC)
thread_title:  Units in the middle? 

message: Perhaps someone can edit this to make grammatical sense? The full sentence in the "Basic concepts" section currently reads:
    "This is usually illustrated by presenting data for three materials, such as air, water and steel, which also have vastly different levels compressibilities which more than make up for the density differences."
Tonyfaull (talk) 13:19, 17 September 2018 (UTC)
replies: text: I took a stab at it. Spiel496 (talk) 22:59, 19 September 2018 (UTC)
thread_title:  Odd wording: "vastly different levels compressibilities" 

message: I'd like to point out that the graph next to the MacKenzie formula
does not correlate to a practical application of said formula.
C++ implementation
double SoundSpeedInSeaWater( double Celsius, double pptSalt, double mDepth ) // MacKenzie
{
    double T = Celsius;
    double T2 = T*T;
    double T3 = T2*T;
    double S = pptSalt;
    double D = mDepth;
    double D2 = D*D;
    double D3 = D2*D;
    return 1448.96 + 4.591*T - 5.304e-2*T2 + 2.374e-4*T3 + 1.340*(S-35) 
         + 1.630e-2*D + 1.675e-7*D2 - 1.025e-2*T*(S-35) - 7.139e-13*T*D3;
}
Sample output from MacKenzie formula:
This table, at 25C and 3.5% salinity, shows that MacKenzie is always increasing..
Specifically, it lacks the minimum at the deep sound channel.
*    0.0 m: 1534.294375 m/s
*   50.0 m: 1535.109792 m/s
*  100.0 m: 1535.926032 m/s
*  150.0 m: 1536.743084 m/s
*  200.0 m: 1537.560932 m/s
*  250.0 m: 1538.379565 m/s
*  300.0 m: 1539.198968 m/s
*  350.0 m: 1540.019129 m/s
*  400.0 m: 1540.840033 m/s
*  450.0 m: 1541.661667 m/s
*  500.0 m: 1542.484019 m/s
*  550.0 m: 1543.307074 m/s
*  600.0 m: 1544.130820 m/s
*  650.0 m: 1544.955242 m/s
*  700.0 m: 1545.780328 m/s
*  750.0 m: 1546.606064 m/s
*  800.0 m: 1547.432437 m/s
*  850.0 m: 1548.259433 m/s
*  900.0 m: 1549.087039 m/s
*  950.0 m: 1549.915242 m/s
* 1000.0 m: 1550.744027 m/s
* 1050.0 m: 1551.573383 m/s
* 1100.0 m: 1552.403295 m/s
* 1150.0 m: 1553.233750 m/s
* 1200.0 m: 1554.064735 m/s
* 1250.0 m: 1554.896235 m/s
* 1300.0 m: 1555.728239 m/s
* 1350.0 m: 1556.560732 m/s
* 1400.0 m: 1557.393701 m/s
* 1450.0 m: 1558.227133 m/s
* 1500.0 m: 1559.061015 m/s
* 1550.0 m: 1559.895332 m/s
* 1600.0 m: 1560.730072 m/s
* 1650.0 m: 1561.565221 m/s
* 1700.0 m: 1562.400765 m/s
* 1750.0 m: 1563.236692 m/s
* 1800.0 m: 1564.072988 m/s
* 1850.0 m: 1564.909640 m/s
* 1900.0 m: 1565.746634 m/s
* 1950.0 m: 1566.583957 m/s
* 2000.0 m: 1567.421595 m/s
While the graph itself may be correct (e.g per UNESCO standard),
I do not think it should be placed next to an uncorrelated formula.
For now, I added a note that the graph does not depict the
MacKenzie formula, It might clarify the inherent confusion ?
Revision: I just realized that the discrepancy of the graph is due to
the fact I don't have the temperature data for the different depths.
For my own part, I'm tempted to do a least-squares curve fit against
the graph, knowing full well it will not fit all locations.
Just my penny to the pot.
Love Nystrom (talk) 14:18, 25 September 2018 (UTC)
thread_title:  Sound speed in seawater - MacKenzie vs. graph 

message: At 0˚C/32˚F (worldwide standard), the speed-of-sound in air is ~332 meters per second, 1,195 km/h, 742.5 mph. 2601:580:10A:E108:DE6:F40A:E32C:69E9 (talk) 23:35, 13 December 2018 (UTC)
thread_title:  At 0˚C/32˚F (Worldwide Standard), the speed-of-sound in air is ~332 meters per second, 1,195 km/h, 742.5 mph 

message: The section "Equations" says the speed of sound comes from derivative of pressure with respect to density "at constant entropy". This is ambiguous, since entropy is extensive and this derivative involves intensive quantities. It could be understood to mean constant entropy density, but that would be wrong. The standard assumption is that the compression is adiabatic, which means constant entropy per particle (in a system where the number of particles is a conserved quantity).  I  suggest it be edited to say this clearly.
Dark Formal (talk) 01:44, 7 April 2019 (UTC)
thread_title:  Adiabacity condition and Entropy 

message: # I don't think the "Basic Concepts" section for a  general topic like this should start with an immediate analogy to a spring system. I think a lot of people will be more confused by trying to imagine a linked spherical spring system--not everyone has an engineering degree and this is a more general topic. The general equation for speed of sound has 3 parameters.
# This sentence: Given that all other things being equal (ceteris paribus), sound will travel slower in spongy materials, and faster in stiffer ones.
This reads odd: it paraphrases a Latin phrase (then links to the Latin expression), provides an uncited heuristic, and doesn't explain what "other things" are being held equal.
I think:
* The lesson in Latin is unnecessary as the expression doesn't relate to the topic
* Without an explanation of what variables are being held constant (even in a general sense as it's a "basic" section) makes this unclear and imprecise
* This description seems to go back a step from the introduction in terms of detail
# Paragraph 5 should explain what "compression-type" sound is as it seems to imply that it's contrasting the first part of the paragraph against that. (The term is explained later in this section)
# Paragraph 6 describes how textbooks are sometimes incorrect, without a citation, and then provides an example that isn't consistent with that claim
# Paragraph 7 doesn't add any value. It refers to a specific location and the only conclusion a reader would come to is "sound takes time to travel". JackW2 (talk) 10:39, 23 January 2021 (UTC)
thread_title:  Problems with "Basic Concepts" 

message: The derivation really sucked.  I am wondering if it came from a Dr. Seuss coloring book?  I had no idea his PhD was in physics until now.  I fixed it a little, but I don't have time to do a real fix.  The remaining problem is too serious for it to be worth it for me to fix given the chance of some revert by bigwigs here. I mean I could fix it but I'd use math I doubt you mods want here since it might be too advanced for whatever this page is for. (High school AP students?) 
If there's encouragement I'll consider it. 
Anyways, the issue is the whole approach, but for one thing it assumes steady state for parts of a differentially accelerating compressible fluid/gas.  Here's what it says now:
"Consider the sound wave propagating at speed v through a pipe aligned with the x axis and with a cross-sectional area of A. In time interval dt it moves length dx=vdt. In steady state, the mass flow rate \dot m = \rho v A  must be the same at the two ends of the tube, therefore ... Per Newton's second law, the pressure-gradient force provides the acceleration..."
If you need a laugh or don't get what I'm whining about, just click on the phrase steady state above.
--Jason Arthur Taylor Jasontaylor7 (talk) 22:30, 28 March 2021 (UTC)
thread_title:  Steady state (contradiction in derivation of speed of sound) 

message: I added... At 0°C/32°F, the speed-of-sound is 1192 km/h, 741 mph.<ref]https://www.weather.gov/epz/wxcalc_speedofsound </ref] 2601:589:4801:5660:2883:21C1:122A:78D5 (talk) 13:58, 17 June 2021 (UTC)
thread_title:  At 0°C/32°F, the speed-of-sound is 1192 km/h, 741 mph - weather.gov  

message: Hey there, just passing by, but shouldn't Vincenzo_Viviani be mentioned in the history part? He got a very precise figure in 1656 (in October, so probably around 15-20°C, the 350m/s measured is just 5-10m/s off). | Link for reference. Feel free to add if you agree ; I probably won't see any answer posted here. Cheers, 81.249.166.253 (talk) 11:39, 14 June 2022 (UTC)
thread_title:  [[Vincenzo_Viviani]] 

message: The lead uses "as fast" while Basic concepts uses "times faster", and both are used to mean the same thing (times the speed of). I don't know if either is preferred on the site, but it's inconsistent. I'd support changing all uses to "as fast" personally, but the issue is contentious so I'd rather not start an edit war. I'd at least like one phrasing to be used throughout the article. Zombiewizard45 (talk) 20:33, 25 July 2023 (UTC)
replies: text: I don't like "times faster".  Let's go with "59% faster" or "1.59 times as fast".  With "times faster" I don't quickly know if I should be using 59% or 1.59 -- and I don't want to have to think that hard. —Quantling (talk | contribs) 14:03, 26 July 2023 (UTC)
thread_title:  Times faster vs. as fast