Am I Hearing Things?

[handsoff]

This is quite possibly going to make me sound a bit daft, but that's fine and has been said before!

When listening to recorded music from a building with a long reverberation period I have noticed that after a long and loud chord has been released the pitch of the notes appears to sharpen very slightly as the echo dies away. This isn't particular to any organ, music or building and is independent of the type of media on which the music is played.  I can't come up with a rational reason as to why this might be the case and A level physics is too far in the past to help.

Am I hearing things?

 

 

 

[S_L]

I can feel Dr. Colin revving up for one of his wonderful replies - and, not having a Science O level to my name, (he says proudly!) I won't have the faintest idea what he is talking about! But it will answer your question!!!

[ick1508]

It's easy enough to find out. Does anyone have a spectrum analyser and a microphone? Just watch the decay of a single note on the screen and see whether it drifts. 

I'd bet on some issue of inaccuracy in the inner ear.

The tone will of course change as the sound decays, as reverb time is different for different harmonics of the note. I vaguely remember the acoustician who designed the acoustics of Snape Maltings saying that the 'warm' sound of the concert hall was due to a longer reverb time at lower frequencies, and had a picture to prove it, but that was 40 years ago. Does anyone have a book on psychoacoustics, Fletcher-Munsen equal loudness curves, all that stuff?

[pwhodges]

A fall in pitch may also be observed.  I have always thought of this an an illusion, based on a change in pitch perception at different amplitudes.  However, I have also seen an informal physical explanation based on the idea that the sound excites resonances which are near to but not quite at the pitch of the notes, and that these persist longer than the original, thus actually changing the pitch as the original fades.

I do not know of any studies of this phenomenon, but I note that some electronic synthetic reverberation devices include a slight change of pitch in their algorithms to simulate this effect, so there must be a somewhat widespread awareness of it.

Paul

[innate]

Not exactly on topic but I recently tuned our harpsichord with the aid of a Digital tuning app on my iPhone. The pitch of a harpsichord string seems to fluctuate as it is plucked and the sound fades. The relevance, I suppose, to the OP is that when we listen to harpsichord music we (or I) are not aware of this effect.

[Colin Pykett]

I don't think handsoff is hearing things.  A pitch change when the intensity of a constant-frequency sound changes fairly rapidly is a well known phenomenon, though it is subjective and therefore an aural illusion.  Like Paul, I experience a slight flattening effect though, rather than a sharpening.  It's particularly noticeable (for me) when the last chord of Saint-Saens's organ symphony dies away into the reverberation on the Fremaux/CBSO recording with Christopher Robinson playing the organ (Classics for Pleasure 0946 3 82233 2 0).  However I once demonstrated the effect to an otological university research specialist, who could not detect it at all, at least on that particular recording, though he was aware of the effect in general.  It isn't an artefact caused by the reverberation as such as this only affects the sound intensity; it cannot change the frequencies involved, unless something is moving in the auditorium and thereby imposing a Doppler shift on the sound.  People moving around can sometimes generate such frequency (in fact, phase) shifts which can be noticeable, though this would not usually happen at an actual concert until the sound had completely died away and the audience started to leave their seats.  And on the CD referred to above there was no audience, though it's conceivable that someone such as an engineer was creeping around close to the microphones I suppose, or maybe a sound-absorbing curtain was wafting around in a draught from the air conditioning, though I'm clutching at straws now.  However, and getting off-topic, this business of people creeping around can ruin attempts to record high quality sound samples from organ pipes - I've certainly come across that from time to time in some 40 years of trying to do it, and it's usually not until you come to replay them that you realise they've been corrupted in that way (and at that point it's difficult to resist the temptation to kick some ass ... ).

[Stanley Monkhouse]

I'm coming to the conclusion that perceptions of pitch, or do I mean tuning?, have subjective elements. At the age of almost 70 with conductive and sensorineural loss in both ears, I've recently noticed that, in a melody, notes above about treble E sound "off". I've long felt that organs sound better in cold, damp churches (I think I mentioned this before), and that music by such as Buxtehude, Bruhns and Tunder sounds extraordinarily exciting on non-equal temperament organs, but somewhat dull on ET. Is there such a thing as standard perception? I very much doubt it.

[pwhodges]

Colin - I actually experience a sharpening, in the cases that I notice it at all; I was reporting that others say they perceive a flattening.  Sharpening seems to be the commoner experience, though - and as you say, it's hugely variable between people and circumstances.

The proposed pysical explanation wasn't suggesting that the frequencies changed, but that new resonances are started by the energy absorbed by resonant material from the original.  I am not convinced though, any more than you are - some psychoacoustic explanation is more likely.

Paul

[Colin Pykett]

Apologies for the misunderstanding, Paul.  Reading your post more carefully I can see what you were saying.

And continuing with psycho-acoustical effects such as those hinted at by Stanley, apparently there is a condition in which the two ears perceive different pitches for the same note (I think it has a medical name but can't remember it - maybe Stanley knows).  In one case the difference was reported to be about a semitone!  Maybe this might help to explain why some people embrace atonal music with its dissonances more enthusiastically than others, if their ears and brains process sound differently to those who prefer tonal music?  Or why some people genuinely might be 'tone deaf' and get little pleasure from music?

[Stanley Monkhouse]

No idea Colin. I have a friend, same age, who can hardly bear organs that aren't perfectly "in tune" (ET), I like a bit of out-of-tune-ness. (How can you enjoy French organ music if the organ is in tune?) I kid myself that it's a recently discovered variable temperament.

It may not be relevant to this, or indeed anything else, but while I like an undulant effect tuned sharp, I find flat-tunes ones almost distressing.

[Colin Pykett]

25 minutes ago, Stanley Monkhouse said:

It may not be relevant to this, or indeed anything else, but while I like an undulant effect tuned sharp, I find flat-tunes ones almost distressing.

Hope-Jones's Worcester cathedral organ (1896) had a 3-rank celeste consisting of unison, sharp and flat ranks.  The stop tablet had an extra detent - when half-on it spoke the unison and sharp ranks, plus the flat rank when pressed fully on.  From what I've read, I don't think you could choose the flat/unison combination on its own though.  (There might have been a similar one on his organs at your former churches in Burton - St Modwen's and St Paul's.  Without looking it up I can't recall.  That at St Paul's was built a couple of years before the Worcester one and there is anecdotal evidence that the cathedral luminaries might have visited it before deciding to commit themselves to the same builder).

Going back to illusions or sensorial degradations, optical degradations have their place in art just as aural ones might have in music.  Monet's cataracts influenced his paintings owing to the fogginess, diminished colour discrimination, random crystalline pixellation and multiple images caused by the condition.  Having had them in both eyes myself, I can fully understand his descriptions of what he experienced and also the progression of the condition as evidenced by his work.  I was astonished at how 'clean and bright' the world suddenly (re)appeared when I had bilateral lens implants and had no idea until then as to how poor my sight had actually become.  On the music front, over the last 20 years or so I've become progressively less fond of Bach's (and similar composers) restless contrapuntal style, turning instead to later romantic works with lots of colour and heavy chords.  Rachmaninov is bliss!  I do wonder whether this is something to do with how my hearing has changed, much as Stanley has described (presbyacusis, basically).  Hearing aids are good for speech as we've discussed exhaustively on previous threads, but for me they don't really cut it for music and I prefer to use other things such as graphic equalisers.

[Stanley Monkhouse]

HA no good for me either. Not even for speech. I need well-enunciated consonants. Very rare these days. The increasing predilection for romantic stuff, too, I understand. Frank Bridge does it for me at present: the six pieces are just delightful, esp the Allegretto grazioso, the F minor one and the D flat major one (can't remember names).

[handsoff]

Thank you to all who have replied and especially to Colin for his lucid explanation. I am glad I'm not alone in experiencing or perhaps noticing the apparent pitch change. The idea of a a trompe l'oreille is fascinating but no more difficult to understand or accept than the ocular version.

At least I haven't, to use an old Warwickshire phrase, "gone all yampy"!

 

 

[Steve Goodwin]

19 hours ago, pwhodges said:

Colin - I actually experience a sharpening, in the cases that I notice it at all; I was reporting that others say they perceive a flattening.  Sharpening seems to be the commoner experience, though - and as you say, it's hugely variable between people and circumstances.

Paul

Paul - I get this too - definitely a sharpening for me.

Steve

[OwenTurner]

I remember a time when a very sensitive large tracker instrument I knew was due its first rebuild and, having not played or heard it for a number of years before, I could detect a flattening on key release on the Great (inevitably most used and worn) particularly on wider flues which I would presume to need more wind. My theory is that the pallets were slightly suffocating the pipes as opposed to shutting them dead and caused an audible drop in wind pressure while still slightly speaking. The observation went away after rebuild, which had no tonal or action modifications.

I think a lot more musical and scientific attention is given at the pluck than the release. I presume we've all been fascinated by the effects of shuttting off the wind while holding a big chord? If some pipes are inherently slower to cease, and those are the bigger ones, and we know the higher frequencies drop out acoustically first over distance, that would leave the big boomers as the last sound standing. Too much conjecture in there for one logic jump of course.

[Damian Beasley-Suffolk]

This intriguing question set me off to look for a book, " The Acoustical Foundations of Music", 2nd edition, by John Backus, published by W W Norton. This is the only technical book my wife possesses, and was a set book for her music degree. She claims never to have opened it - judging by its condition, I believe her.

In a short chapter "Frequency and Pitch" it describes a few of the points made in this discussion. The good news is that we aren't hearing or imagining things, although how we perceive the same sounds varies between individuals. Just for interest, here they are:

- The perceived pitch of a tone can vary depending on intensity. "The effect seems to vary greatly from person to person; some do not hear it at all. On the other hand, one individual reported an apparent drop of almost a whole tone when a sound of 200Hz was raised from 40 to 100dB. The effect apparently exists only for pure tones; it seems generally that complex tones show no change in pitch with intensity."

- " The two ears with which we hear pitch are not necessarily identical. In some individuals, a sound of a given frequency may produce a certain pitch in one ear and a different one in the other; this condition is called diplacusis. It is apparently negligible in normal hearing but can be produced by disease or injury to the ear."

- " As a result of recent work [as of 1977!] it now appears that the ear responds to a periodic change in the pattern of sound stimulus. This has already [in the book] been discussed in connection with beats; if we listen to two pure tones of frequencies of 500Hz and 501Hz, we hear one beat per second. In this case we have an actual rise and fall of sound intensity once each second. [...] However, if we sound together, say, two tones of frequencies 250Hz and 501Hz, we again hear a periodic change in the sound, once per second. In this case, there is no intensity change, but the waveform repeats once each second, and the ear can hear this change. If the change in the pattern of a sound stimulus is fast enough, the ear will hear a sound of this frequency, even though no such frequency is present in the original stimulus. The frequency so heard is called the periodicity pitch."

 

That's enough quotation for the moment, but the point is that what we perceive from what we are hearing is within a rather broad range of normal. The text also makes a distinction between frequency, which can be measured, and pitch, which is perceived by the user in comparison with some internal reference.

Personally, although aware of the subjective flattening of a chorus when a swell box is closed, I don't hear it, although I am aware of the more rapid attenuation of higher frequencies and change in tone colour as the shutters close. Similarly, I think, with the dying fall of a chord in a reverberant building. However, as someone pointed out above, some electronic instruments appear to model a slight flattening with reverberation. My quite new electronic does this, its longest "acoustic" setting is a Basilica with 8.7 seconds. With its Baroque specification, which is otherwise very nice, this electronic flattening makes the whole thing sound out of tune and is very unpleasant, and I can't turn it off - I have never experienced this in real life. It doesn't happen with the other specs, which makes me wonder if it's something to do with the many tierces and quints. This is where natural differences in perception cause interesting problems.

My own auditory foible is that along with my thankfully still normal hearing across the standard spectrum, in my left ear I can hear very low tones, and in my right very high tones. I'm not sure what evolutionary advantage this gives me, but it's very handy for tuning my organ and harpsichord. And, as I grew up in Bristol and spent years listening for the infamous "Bristol hum", which is said to be within range of my left ear, I have never heard it, and I think it's just a myth or meme!

 

[OwenTurner]

Hmm, disconnecting pitch from frequency is a bit courageous. Did the chapter on the Earth being flat include anything to do with reverberation effects when you get to the edge of the world and there's nothing for sound to bounce off?

I feel this book is confusing brilliance with pitch, where brilliance is upper partials. In the case of a swell shutting the impact on the higher pitches is inevitably greater than the lower so you will lose some power at the upper, but the pitch of a note is surely the same. Perhaps we need to consider "Shrodinger's Swell Box" as a theorical physics challenge; though the cat would probably create too much destruction to the pipes and action.

I've just ordered a second hand copy of the book of ebay.

 

[Colin Pykett]

Although it might be intuitively strange at first acquaintance, subjective pitch doesn't always track frequency.  For this reason it's measured in mels, not Hz.

As for cats inside organs, one of ours (long since gone to the great cattery in the sky) was in the habit of crawling into the swell pedal aperture of my home organ and going to sleep.  More than once there was a yelping mew when I altered the volume ...  Her sibling didn't make this mistake, but only because she always scurried out of the room whenever I started playing, thereby demonstrating a better-developed sense of musical taste and judgement.

I agree the book mentioned by Damian sounds very much worth getting hold of - thanks Damian.

[Damian Beasley-Suffolk]

The difference between what we may measure objectively and what we perceive is a matter of everyday importance. White LED light bulbs are not white - a nominally white LED emits a piercing steely-blue light, so to make it appear to be white, usually a bit of green is thrown in, by adding a phosphorescent compound which radiates green. It appears to the eyes as pure white, but spectrally it comprises only a few components. Actually, electric lights in general have always had this problem, hence the Colour Rendering Index and other efforts to quantify it - but it's all to do with human perception and, as we know with colour blind people, this varies greatly. I have also read of people, predominantly women, who instead of three colour groups of colour receptors in their eyes, have four. Their perception of colour is, apparently, quite intense.

Back to organs, as I write I am listening to Ben van Oosten playing the Finale of Guilmant V at Rouen. To my ears, along with the organ I can hear a huge choir singing "Ahhhh". I'm fairly sure that there isn't one there. Perhaps this is the effect of an enormous instrument which is for most purposes in tune, but the combined effect of hundreds of normal variations in frequency and phase contribute to this wonderful, broad, breathing sound, without sounding in the least out of tune.

[Barry Oakley]

 

 

I understand that when the Forster & Andrews/John Compton organ, including the console, in Hull Minster is overhauled, cleaned and renovated, the Compton luminous stopheads are to be retrofitted with LED’s. Have, I wonder, any other similar Compton consoles been so retrofitted?

When, in 1939, the console was first used, the intensity of incoming natural light was so strong that it neutered the stops’ tungsten light output and individual brown paper discs were cut and inserted to produce warm glows when stops were actuated.

[Rowland Wateridge]

On 12/04/2020 at 16:16, Colin Pykett said:

As for cats inside organs, one of ours (long since gone to the great cattery in the sky) was in the habit of crawling into the swell pedal aperture of my home organ and going to sleep.  More than once there was a yelping mew when I altered the volume ...  Her sibling didn't make this mistake, but only because she always scurried out of the room whenever I started playing, thereby demonstrating a better-developed sense of musical taste and judgement.

 

About 20 years ago, I had an experience like this while playing for a service at a local church in Hampshire - a small, rather nice organ with detached console by George Sixsmith.  Strange noises were coming from within the console and something was clearly moving.  After the service, a screwdriver was produced and the console back panel removed.  Out jumped the vicar’s cat, fortunately unscathed and, equally, no damage done to the console interior.  I guess the action was on 12 volts, but there must have been the possibility of potential contact with 240 volts, so both the cat and the organ were fortunate to survive the experience.

[Denis O'Connor]

I believe that Faure experienced difficulty with his hearing in later life. Upper frequencies sharpened and lower frequencies flattened.

[Colin Pykett]

On 11/04/2020 at 16:37, Stanley Monkhouse said:

... The increasing predilection for romantic stuff, too, I understand. Frank Bridge does it for me at present: the six pieces are just delightful, esp the Allegretto grazioso, the F minor one and the D flat major one (can't remember names).

Thank you for opening this new window for me, Stanley.  My education has been sadly neglected until this day.  Is the D flat one Andante con moto?  And am I right in thinking that Bridge didn't even play the organ?  If so, it's that bit more remarkable how he wrote for it so atmospherically.  Sheet music is available on IMSLP, and several recordings on CD and youtube (e.g. 'Sounds Idyllic' on a disc by Peter Dyke).

[Rowland Wateridge]

A further interesting diversion from the topic.  How do non-organists adapt to composing and writing on three staves? Has someone written anything about this? 

[AJJ]

In my experience they discuss with an organist. A piece I commissioned from a non organist was essentially a keyboard piece. I took it and edited, played it to the composer who liked what she heard and all were happy!

AJJ