Do vocal tract resonances assist a singer's pitch control?

[Swamp Thing]

Wolfe et al (Vocal tract resonances in speech, singing, and playing musical instruments) say in the abstact:

In both the voice and musical wind instruments, a valve (vocal folds, lips, or reed) lies between an upstream and downstream duct: trachea and vocal tract for the voice; vocal tract and bore for the instrument. Examining the structural similarities and functional differences gives insight into their operation and the duct-valve interactions. In speech and singing, vocal tract resonances usually determine the spectral envelope and usually have a smaller influence on the operating frequency. The resonances are important not only for the phonemic information they produce, but also because of their contribution to voice timbre, loudness, and efficiency.

Now, I recently got interested in the role of the vocal tract in achieving pitch accuracy. Regarding this aspect Wolfe et al discuss it in the case of wind instruments but not in singing:

Wind instruments use the breath of the player as their energy source, and so the vocal tract can be intimately involved, and its resonances can contribute both to timbre and to pitch control.

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Question: I would like to know whether it is true that a singer's

vocal tract resonances ... have a smaller influence on the operating frequency.

as this paper states.

Personally, I suspect that opera singers, for example, could be exploiting vocal tract resonances when they hit each note spot on with apparently no effort. (Also vocalists from many other traditions e.g. Indian classical music).

Example: https://youtube.com/clip/UgkxiXljldtdS955hi4D4V97d6DuYDCKXq9d?si=fh9HBsnREvqaHu3J

My guess is that it is not merely a feedback loop where the singer's brain compares the heard pitch with the target pitch and makes rapid corrections.

I will be looking for more literature, but someone here probably knows more and can point me to good references.

 

[Vanadium 50]

Mariah Carey has a 5 octave range. That's 60 notes. Do you think her vocal tract has 60 fixed resonances that just happen to be properly spaced? This seems unlikely.

I think the model of a trombone - resonances over a continuum - is more accurate.

 

[sophiecentaur]

I suspect that opera singers, for example, could be exploiting vocal tract resonance

Agreed. The basic oscillation of the vocal cords will be very low Q and easy to 'pull' by loading with a cavity. It can't just be a tone generator plus a broad band filter.

The resultant pitch has to be from a combination of muscle tension on the cords and some very clever manipulation of the air spaces around there. Training gives professional singers a massive advantage.

 

[tech99]

The lowest frequency in the male speaking voice is about 300Hz, corresponding to 70cm, so I suppose the vocal tract is long enough to have a resonance this low. But I cannot see how the track can be tunable over a frequency range spanning a few octaves.

 

[sophiecentaur]

so I suppose the vocal tract is long enough to have a resonance this low.

I would imagine that the vocal tract would act more like a Helmoltz resonator (as in a sub woofer) which can resonate at a very low frequency for its size, at the expense of losses.

 

[Swamp Thing]

I just found this

https://www.phys.unsw.edu.au/jw/reprints/AIRSchapter.pdf

which looks promising at first glance as a source of an answer to my question.

The last sentence of the abstract reads

Finally, (this paper) discusses how singers adjust their tracts using resonance tuning to produce louder, more stable voice with less effort.

By more stable, I presume they mean both amplitude and pitch stability. But let me read the paper in its entirety before concluding anything.

 

[sophiecentaur]

The pitch of a Lion's roar is lower than it should be, according to body size. Male lions achieve this by specifically drawing down and elongating their vocal tract beyond its normal length. This actually cost them energy but it's better than getting into a fight. So all male lions pretend they're bigger than they are. Just like swaggering teenagers.

I think domestic cats may do a similar thing. We had a very elderly tom who used to see off bigger, younger cats just by shouting at them.

 

[Swamp Thing]

Male lions achieve this by specifically drawing down and elongating their vocal tract beyond its normal length.

I am male, although not a lion. The reason I got interested in this topic and started this thread, is that I recently stumbled on some interesting vocal phenomena while amusing myself by humming along with some music. I was in a playful mood and began experimenting along the lines of the Mongolian throat singing technique and I suddenly "got" how to produce those high order overtones etc. with minimal effort.

So yes --- "drawing down and elongating my vocal tract beyond its normal length" captures exactly what it feels like doing some of the interesting things that I have been diverting myself with, off and on since that first occasion.

Among other things I can now produce a deep purring sound whose pitch can be held very, very stably with little effort. And I can jump up one octave from that initial pitch, and also go up one semitone at a time and hum simple melodies with a level of pitch accuracy that was impossible for me before.

 

[sophiecentaur]

I am male, although not a lion.

I guess we all use our voices 'at a cost' to other abilities and energy input but the anatomy of a male lion seems to produce lower and louder sounds at the expensive of significant performance in other ways.

 

[Swamp Thing]

I just found this

https://www.phys.unsw.edu.au/jw/reprints/AIRSchapter.pdf

which looks promising at first glance as a source of an answer to my question.

Have now read through this a couple of times. It offers a wealth of information that is helping to bring me up to speed on this new interest -- nay, this new passion -- of mine. But it doesn't address my hypothesis that singers use certain physical resonances in order to cue themselves in to the exact "position" of each note, and to create a feedback loop that brings them (and keeps them) spot on every time. Or at least, some singers do this, at least during a part of their learning curve, in order to accelerate that learning; and potentially even use it throughout their career.

 

[sophiecentaur]

But it doesn't address my hypothesis that singers use certain physical resonances in order to cue themselves in to the exact "position" of each note

A brilliant paper; such a lot of ideas there.
On a personal level, I can agree about 'physical resonances' which we can use for timing / frequency. Some notes just 'feel right' when I tune my guitar. It can feel a bit flat or a bit bright sometimes and a check with the iphone usually agrees. I guess there will be external references when using a musical instrument, such as the resonances of the structure, miles away from E but related in some way that our memory identifies for that particular instrument. Room acoustics in combination with memory could do a similar thing.

As well as forming musical notes with accurate pitch, timing accuracy can be very good with sportspeople. A rowing eight seem to agree on stroke rate to less than one per minute. Swimmers, with bad visibility, can tell exactly when to begin a turn after 50m of energetic strokes.