Effect of temperature on tuning

[SteveS]

I've noticed quite a large deviation in tuning between now and over 4 weeks ago.

Then, my A=440Hz was within 0.5 cent from true, with a room temperature then of about 19C. 

Now the ambient room temperature is around 13C, and my A=440Hz is +1.2/+1.5 cents out.

Can this temperature difference account for this degree of shift in the tuning of about 1 cent?

I'm moving the concertina to a warmer room to see if that makes a difference.

[SteveS]

Moving the concertina to a warmer room and checking the tuning gave me readings of A=440Hz +0.4/+0.6 cents.

A shift in tuning of -0.8 cents due to an increase in temperature of approximately 6C.

[ttonon]

Hi Steve, according to my calculation for the frequency of the first transverse mode vibration of a cantilever, and assuming a steel tongue, changing temperature from 19 degrees to 13 degrees would increase the pitch by only 0.24 cents. 

 

Your experiment gives a minimum of 0.4 cents change, which isn't too far off, and I'd attribute the difference between your result and mine to the impreciseness of your temperature and pitch measurements. I think we'd both conclude that the 1.2/1.5 cents discrepancy you originally measured (assuming these were accurate) may be due to things other than temperature. Can the difference be due to barometric changes? Well, let's see.

 

Barometric pressure at sea level can easily change from about 29.5 to 30.5 mm mercury, or about 3.4%.  Because of the ideal gas law at constant temperature, that's also the percent change in density.  The pitch of free reed vibration depends on air density because the driving force is the kinetic energy of the air that gets intermittently stopped when airflow passing through the slot is suddenly stopped.  The kinetic energy of air is = (rho*V^2)/2, so a percent change in rho is a percent change in kinetic energy.

 

The relation between air density and pitch is complicated, but if we're talking about something like one percent changes, one percent of a frequency change would be from 440 to about 436, or about 16 cents. That's of course way too large, but intuitively, it tells me that yes, barometric effects on pitch can possibly explain much of the original pitch difference. 

 

Maybe you'd want to verify this by recording pitch measurements along with accurate barometric measurements. 

 

Best regards,

Tom

www.bluesbox.biz

[alex_holden]

Another possible factor is a change in the frequency of the reference oscillator in your tuning device.

[SteveS]

24 minutes ago, alex_holden said:

Another possible factor is a change in the frequency of the reference oscillator in your tuning device.

I'm using Peter's iStrobeSoft on my iPad - I assume the reference oscillator shouldn't have changed in 3 weeks.

Mind you I've dropped my iPad a few times....😶

I'll check the tuning against the same tuner on my iPhone as a consistency check.

Edited November 24, 2023 by SteveS

[alex_holden]

2 minutes ago, SteveS said:

I'm using Peter's iStrobeSoft on my iPad - I assume the reference oscillator shouldn't have changed in 3 weeks.

Mind you I've dropped my iPad a few times....😶

I'll check the tuning against the same tuner on my iPhone as a consistency check.

Oscillators are affected slightly  by temperature changes though. Very accurate laboratory frequency references place the oscillator inside a thermostatically controlled oven.

 

I find I get a slightly different result from my iPad and my iPhone (running the same software), so I now only use the phone for tuning to avoid chasing my tail too much.

[SIMON GABRIELOW]

just think how you feel yourself in a cold room [shivering away] and you move into a warmer one! 

So, do same with your concertina, keep it wrapped up in a scarf or blanket😊.

[ttonon]

On 11/24/2023 at 12:20 PM, alex_holden said:

Another possible factor is a change in the frequency of the reference oscillator in your tuning device.

Alex, upon reading this thread again, I'd like to say that I don't think there's much basis for your suggestion. Of course, no reference is perfect, but I think you're not realistic, in an example of a "little knowledge can be a bad thing." Do you realize that resistors, capacitors, inductors, etc. have temperature coefficients measured in parts per million per degree C? Even a lousy crystal oscillator measures at the worst a part in ten thousand. You need to realize that a primary criterion for a good reference is temperature stability. That's why they are called "references." They are chosen such that the fluctuations resulting from normal use are not noticeable. I don't think Peterson could advertise 0.1 cent accuracy if their measurements would noticeably fluctuate with relatively minor room temperature variations, as is the case here. Maybe you'd like to search out the temperature coefficients of resistors, capacitors, inductors, etc. used in printed board circuitry and get back to us. Google is our friend who can keep us real. 

 

Best regards,

Tom

[robert stewart]

I have been playing acoustic instruments (professionally), including English concertina, since the late 1960s (in Britain, then in the USA). Britain had a colder and wetter ambience for many years until central heating or similar systems became widespread. As we probably all know, the Victorian/Edwardian eras were distinctly cold, wet, and smokey  when compared to the present. Cities especially were horribly polluted by smoke, mainly from coal fires (think of London, or Bath, or Glasgow etc). Thus the great concertinas of the past were made and played mostly in colder damper dirtier environments than those we store and play instruments in today. In the US, of course, much of the struggle is to keep high quality instruments (of all sorts) humidified, especially in the stunning aridity of the East Coast and the Mid West.

 

There seem to be several conclusions we can consider, but one stands out: musicians were less concerned about "accurate" pitch and pitch variations. There were no digital tools for measuring frequencies. Tuning forks tended to be the standard. This does not mean that musicians were slipshod and careless, but that they played, together or solo, with more concern for music than for tiny pitch variations. Many examples of early recordings show quite different tonal and pitch textures to contemporary modern recordings, and the difference is often thought of as being due to the old recording and pressing (discs, cylinders) methods. But, at least in equal part, they are due to the way ensembles and solos actually sounded.

 

In the Middle East and Mediterranean , or in India (and many other countries) musicians playing together spend time collectively adjusting the modes/scales on their instruments before they actually play anything. But of course, we cannot do that with the concertina.

 

Robert Stewart (currently playing a beautiful extended scale Edeophone from the early 20th century. Which has several "flat"notes, of course. Or are the others sharp?)

[ttonon]

1 hour ago, robert stewart said:

they played, together or solo, with more concern for music than for tiny pitch variations.

Thanks for that interesting perspective and I believe there's much truth to it. Of course, there are people fortunate enough to have perfect pitch, either absolute or relative, but that doesn't detract much from your statement. 

 

In addition, as we age, our hearing generally deteriorates, sometimes severely. I in fact went through a tragedy by suddenly losing all my hearing in my left ear and about half my hearing in my right ear. It happened in two stages, over only a couple of weeks. I can't explain here all the complex consequences to such an event, but my musical performances suffered severely, and I even stopped playing with others in small groups or even going to local concerts. 

 

That happened about 10 weeks ago, and I've adjusted somewhat, but basically, I'm extremely grateful for the half ear I have left and shudder to think about my losing even that. I mention it here only to point out the many real issues we humans are involved with and sometimes we can get lost on issues that are of little importance. 

 

I also want to mention that a few years ago, when I still had decent hearing, I noticed that I'd perceive a certain pitch to a musical tone with my "good" ear, and a slightly different pitch with my "bad" ear. This is just another interesting part of this effort to tune musical instruments to the "right" pitch. 

[David Barnert]

14 minutes ago, ttonon said:

Of course, there are people fortunate enough to have perfect pitch

 

“Fortunate” may be the wrong word... I once knew an orchestral conductor and pianist who had perfect pitch but grew up in a household with a piano that was a quarter tone flat.

 

16 minutes ago, ttonon said:

I in fact went through a tragedy by suddenly losing all my hearing in my left ear and about half my hearing in my right ear. It happened in two stages, over only a couple of weeks.

  ...

That happened about 10 weeks ago...

 

So sorry to hear about this.

[ttonon]

2 hours ago, David Barnert said:

 

“Fortunate” may be the wrong word... I once knew an orchestral conductor and pianist who had perfect pitch but grew up in a household with a piano that was a quarter tone flat.

 

 

So sorry to hear about this.

Hi David, thanks. But I wonder, why would a person with perfect pitch be annoyed by a piano that's tuned to a different standard than the world's orchestras? As long as the piano is tuned within itself, why would it matter, especially since the standardized pitch of middle A is a convention?

 

With my hearing loss, it's interesting that Paul Simon made the same announcement, that he lost all hearing in his left ear, within days of when it happened to me. I read that doctors have labelled it "Sudden hearing loss," with no explanation of why it happens. However, I did abuse my ears when I worked as a carpenter in the early 1980's. Especially my left ear, when I put my head very close to the circular saw, in order to cut on the pencil line. I sometimes asked, "Do you want the cut on the left, the right, or the middle of the line?" Stupid me. But after a month or so, it hit me like a ton of bricks that I was probably damaging my ears, then started stuffing my ears with things, in the days before all the warnings and devices for hearing protection. 

I remember one time, when I was hammering in roofing nails. I stopped to stuff my ears with pieces of a plastic bag and the boss walked by, saying, "Oh Tom, don't worry about those small hairs. They eventually break and you won't need to worry about it. 

 

But it's curious that it took decades for the final collapse. My question is, why such a complete collapse of all frequencies? Any noise has a spectrum of intensity, and so I'd think that some frequencies would still respond. It may be that the saws, the hammers, and other noises together covered the full frequency width.  

 

Best,

To,

[David Barnert]

34 minutes ago, ttonon said:

But I wonder, why would a person with perfect pitch be annoyed by a piano that's tuned to a different standard than the world's orchestras? As long as the piano is tuned within itself, why would it matter, especially since the standardized pitch of middle A is a convention?

 

It didn’t bother him as a child, but it made a mess of things as an adult professional musician having to daily interact with pianos and orchestras that sounded out of tune to the ear he developed as a child.

[RAc]

18 hours ago, ttonon said:

Alex, upon reading this thread again, I'd like to say that I don't think there's much basis for your suggestion. Of course, no reference is perfect, but I think you're not realistic, in an example of a "little knowledge can be a bad thing." Do you realize that resistors, capacitors, inductors, etc. have temperature coefficients measured in parts per million per degree C? Even a lousy crystal oscillator measures at the worst a part in ten thousand. You need to realize that a primary criterion for a good reference is temperature stability. That's why they are called "references." They are chosen such that the fluctuations resulting from normal use are not noticeable. I don't think Peterson could advertise 0.1 cent accuracy if their measurements would noticeably fluctuate with relatively minor room temperature variations, as is the case here. Maybe you'd like to search out the temperature coefficients of resistors, capacitors, inductors, etc. used in printed board circuitry and get back to us. Google is our friend who can keep us real. 

 

Best regards,

Tom

Tom, I do not understand your harsh judgement and dismissal of Alex's experience and knowledge. First of all, he is an education electronic engineer, and - as you can tell from his feed on instagram - still understands hardware better than many professionals, even though his daily work is not mainly EE.

 

Also, I can sort of back up his statement empirically. A few years ago I owned a Tascam handheld recording device, and for a while I used to experiment with recording both through that recorder and my PC - meaning I would record one track using Cubase and a microphone hooked up to an external sound card, and another track separately on the Tascam, hoping to be able mix those into one recording. Both devices were set to the same metronome speed.

 

When I exported the recording from the Tascam and tried to import the sound file into my Cubase project, I found that the tracks, even though perfectly synchronized in the beginning, would skew away from each other over time to a degree that made it impossible to use this recording technique. So far, there is nothing unexpected here; no two uncoupled oscillators will ever generate a clock source at the exact same frequency (this is, I believe, also the reason why most professional recording devices allow for external clock source feeding).

 

The very interesting thing for me to observe was that the degree of the skew would change over time. I would typically make several recording attempts on either device and try to match the tracks to find the best sounding combination. As it turned out, two recordings from the PC taken at different times would have a varying skew - whereas in one of the recordings, say, the first two minutes were usable before the tracks would deviate from each other audibly, in another one it would be, say, 115 seconds against the IDENTICAL external sound file! A pattern I believed I detected was that a major factor that determined the skew rate was the time after bootup of the PC. 

 

I discussed that phenomenon with a colleague who is a full time embedded hardware developer, and he suggested that indeed, the temperature in the CPU mainboard might well be a contributing factor to the deviation between the two recordings.

 

Needless to say, since all audio frequencies are derived from the CPU clock source, this behavior would affect both metronomes and tuning software.

 

I will agree that devices specifically designed for use with audio applications will have additional compensation components to ensure frequency stability, but this does not necessarily apply to consumer devices such as PCs, tablets and smartphones.

 

Btw, it is terrible to hear about your hearing issues, that must be a very hard burden to carry - I am afraid I can not wish for you much more than a stop of the deterioration; miracle hearings are supposedly very rare with these conditions - all the best!    

Edited January 7 by RAc

[Richard Mellish]

Both the pitch of a reed and the clock frequency in a smart phone (or whatever device) can drift over time. However the specific effect of temperature could be investigated fairly easily. Note the pitch, as indicated by a tuning app, with both the concertina and the phone at room temperature. Then put one of them somewhere warm (such as an airing cupboard) or cold (outside in winter) for half an hour while keeping the other at room temperature. Note the pitch as now indicated by the tuning app. Then swap them over, wait another half hour, and note the pitch again. Throughout, run as few other apps as possible on the phone to minimise internal warming.

[RAc]

17 minutes ago, Richard Mellish said:

Both the pitch of a reed and the clock frequency in a smart phone (or whatever device) can drift over time. However the specific effect of temperature could be investigated fairly easily. Note the pitch, as indicated by a tuning app, with both the concertina and the phone at room temperature. Then put one of them somewhere warm (such as an airing cupboard) or cold (outside in winter) for half an hour while keeping the other at room temperature. Note the pitch as now indicated by the tuning app. Then swap them over, wait another half hour, and note the pitch again. Throughout, run as few other apps as possible on the phone to minimise internal warming.

absolutely. Another fairly straightforward way to investigate temparature effect would be to make two, say, 5-minute recordings of a clicking metronome app on your consumer device at different temparatures as you suggested, export those to another computer (just to be on the safe side) and overlay them in your favorite daw (eg Audacity).

 

 

[ttonon]

RAC, thanks for your impressions on my evaluation of Alex's suggestion, though your technical argument is not applicable to devices like Peterson strobe tuners.

 

I do agree that if Alex chooses so, he can be offended by my claim his suggestion could be a "little knowledge can be a bad thing." That would be his problem. But it seems you yourself chose to be offended. Am I right?

 

We all know of many such examples where people extrapolate true knowledge to erroneous belief, and I made that comment not just for Alex but to all of us who might benefit from the reminder. The web seems to invite such behavior from all of us.

 

And where are your relevant facts? You recite a convoluted story that doesn't explain all the key details necessary to make a scientific assessment of your conclusions, or part conclusions, or "sort of" conclusions, whatever conclusions. Then you extrapolate that into an argument why a Peterson strobe tuner could be inaccurate.

 

Here are the relevant facts: Electronic timing circuits are based on two technologies: RC circuits or crystals. (We also have atomic clocks, but we need not let that confuse us.) Resistors, capacitors, and crystals have strict specifications, according to the class they are assigned to, and that determines their cost. I repeat, do some homework, and find that both resistors and capacitors in IC circuits have temperature coefficients varying from zero to somewhat less than 100 ppm/C, over very wide temperature ranges, and crystal oscillators, depending on the crystal cut, vary from zero to up over 100 ppm/C. That's for the components themselves. Then add to it the facts that compensation circuits can eliminate any significant temperature effect and that typical room temperature variations are only a small fraction of the specification ranges, there's no reason whatsoever to blame the magnitude of the variations people see in tuning free reeds in their own homes. Unless of course they're using a faulty meter or some kind of homemade method to make the measurement.

 

I repeat, Peterson strobe tuners are accurate to within 0.1 cent, which is the smallest unit measured for musical pitch, and - no offense - I trust their engineers more than I trust you with your example. I've read that the top musical schools claim that most people can discern musical tones to within +/- 10 cents. I'd be surprised if people with perfect pitch could detect differences down to 0.1 cents. If I'm wrong, that would be a good example of a "little knowledge can be a bad thing." We do it all the time. 

 

I appreciate the comments you and Richard made regarding ways to test cell phone and computer circuits, and I have no idea how much software is integral to their mechanisms for measuring this. I encourage you to do such experiments. My comments here are restricted to devices with dedicated designs to measure musical pitch and sold with that in mind. Because of my arguments here, I think it not too likely that even cell phone or computer methods could result in the errors mentioned at the beginning of this thread, unless their designs are incompetent. But I could be wrong and would welcome correction.

 

A word on offense. If I told you, "You have a funny nose," and if you never thought about your nose in such a way, you'd either be curious or think I'm a nut. But if you had a history of people discussing your nose and you looking in the mirror with misgivings, you might choose to be offended by my statement.

 

So, if Alex isn't offended by my comment, he's thinking intelligently, understands why I said it, and takes no offense. If he chooses to be offended, he thinks I speak the truth.

 

Thanks for your good wishes,

Tom

[RAc]

55 minutes ago, ttonon said:

RAC, thanks for your impressions on my evaluation of Alex's suggestion, though your technical argument is not applicable to devices like Peterson strobe tuners.

 

...

 

I repeat, Peterson strobe tuners are accurate to within 0.1 cent, which is the smallest unit measured for musical pitch, and - no offense - I trust their engineers more than I trust you with your example. I've read that the top musical schools claim that most people can discern musical tones to within +/- 10 cents. I'd be surprised if people with perfect pitch could detect differences down to 0.1 cents. If I'm wrong, that would be a good example of a "little knowledge can be a bad thing." We do it all the time. 

 

Are we talking the same language here? Steve and Alex explicitly refer to SOFT strobe tuners running on Apple devices. From my understanding, everything realized in software - no matter what algrithm they implement - must use the underlying hardware for reference. Your statements above imply that the tuning apps guarantee high accuracy regardless of the underlying hardware. I do not think that is possible, but of course, I can be wrong too. Please clarify if I am mistaken in my understanding.

 

I have been a professional embedded software engineer for ~30 years, and I work in close cooperation with hardware designers. I am well aware of technical specifications, requirements for industrial systems and how designing hardware works. I was present at numerous systems being tested in cold and heat chambers. Thus I do not need to research or relearn the procedures. Of course you are correct in your elaborations. Yet we are talking consumer devices here, and from my technical experience, I can assure you that quality assurance and -control in consumer frequently falls victim to cost reduction stipulations. For many companies building and selling consumer devices, it may be much more attractive (cost wise) to produce on the lower end of the specification compliance list and risk even a rather high percentage of returns and destruction of malfunctioning devices than design systems that are highly reliable. I am not implying that this happens regularly on Apply smart phones and tablets, but I have experienced what I wrote earlier, and all I am doing is drawing conclusions.

 

As for etiquette: No, I do not feel offended myself, and I do not feel a need to defend Alex, I know him well enough (I believe) to understand that he can do that well enough for himself, so no need to further pursue that strand.

 

I too encourage everybody to conduct experiments along the lines of what Richard and I sketched out. It is not a lot of work, and the more data we gather, the mre reliable the results. I have run a short test this afternoon involving my Surface pro tablet, and in 2 5 minutes recordings at about 8 vs. about 15 degrees celsius, I was not able to reproduce and audible (or visualizable) skew, I will later attempt to repro the problem on my Celeron Windows PC.

 

Best of luck, enjoy the rest of your weekend! 🙂

Edited January 7 by RAc